Dissertations / Theses: 'Inbreeding depression'

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Ferreira, Álvaro Gil Araújo. "Inbreeding avoidance and the genetic basis of inbreeding depression in Drosophila." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599002.

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This dissertation describes a study of the role of sexual selection in inbreeding avoidance and an extensive analysis of the genetics basis of inbreeding depression using species of the fruit fly Drosophila as model organisms. Using behaviour experiments and molecular genetic techniques I investigated the role of both female mate choice and polyandry in inbreeding avoidance. My results show that in the four Drosophila species analysed (D. melanogaster, D. simulans, D. subobscura and D. littoralis) female flies are not able to avoid inbreeding through mate choice. However, when polyandry was investigated in D. melanogaster and in D. littoralis I found that post-copulatory mechanisms can contribute to inbreeding avoidance. Specifically, females sometimes appear preferentially to use sperm from an unrelated rather than related partner. However, the pattern is complicated and the exact outcome appears to depend on the species, the remating frequency and on male mating order. Concerning inbreeding depression, two main genetic mechanisms have been invoked to explain the deleterious effects associated with inbreeding, one based on the exposure of deleterious recessive alleles and the other on heterozygote advantage. In order to investigate the relative importance of these two mechanisms, I analysed the relationship between heterozygosity at microsatellite markers and fitness in D. melanogaster, comparing inbred and outbred crosses under benign and stressed conditions. It was found that although the effects of deleterious recessive alleles have a significant effect, heterozygote advantage also plays an important role on inbreeding depression. Additionally, I show that the deleterious effects of inbreeding are at least partly environmental-specific.

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Pooley, Emma L. "Maternal inbreeding depression in the Zebra Finch, Taeniopygia guttata." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4590/.

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The aim of this project was to elucidate the mechanisms behind maternal inbreeding depression, using a model avian species, the zebra finch Taeniopygia guttata. Inbreeding can reduce the fitness of inbred animals beyond its negative effects on early survival, through reduced fecundity of inbred animals that survive to reproductive age. In particular, inbreeding has been found to cause a decline in hatching success and early survival of the offspring of inbred mothers. I examined the underlying causes of maternal inbreeding depression by observing the effects of one generation of full-sibling mating on life-history and physiological traits in the zebra finch. The aims of this project were to separate the effects of maternal inbreeding on egg production and subsequent offspring care on the fecundity of inbred females and to examine the possible underlying causes of maternal inbreeding depression. The study explored the following questions; • Does maternal inbreeding lead to a reduction in egg production, either in the number, quality or size of eggs produced? • Do inbred females reduce the level of antimicrobial proteins in their eggs compared to outbred females? • Does inbreeding lead to a reduction in either incubation attentiveness or incubation temperature in females? • Does inbreeding in the egg-laying mother lead to a decline in offspring survival or growth? • Does inbreeding in the foster mother lead to a decline in offspring survival or growth? • Do inbred birds have higher maintenance costs, i.e. higher resting metabolic rates than outbred females? After generating inbred and outbred (control) females from full-sibling and non-related pairs respectively, females were paired with unrelated outbred males at the age of around six months old. The first clutch was removed for analysis of egg production (chapter two). The females were immediately allowed to lay replacement clutches, which were cross fostered among nests of inbred and control females. I then compared incubation attentiveness between inbred and control females using this replacement clutch (chapter 3). Through the cross fostering design I was able to separate the effects of inbreeding in the egg laying (chapter 2) and incubating mother (chapter 3) on offspring viability by comparing offspring growth and survival between treatments. When the same group of females were two years old I compared the resting metabolic rate of inbred and control females by measuring oxygen consumption of resting females in an open flow respirometry system (chapter 4). In chapter two I examined the effects of inbreeding on a key stage of reproductive investment; egg production. I found a reduction in both egg mass and yolk mass in inbred females compared to control females. However, there was little evidence to suggest that the level of antimicrobials deposited to the egg differed with the inbreeding status of the female. Inbreeding in the egg laying mother was found to affect hatchling mass through interactive effects with replicate and clutch size. Inbreeding in the egg egg-laying mother also affected post-hatching survival, although this effect was mediated by hatching order. In chapter three I investigated the effects of maternal inbreeding on incubation behaviour. Inbred females reduced their incubation attentiveness, but did not reduce average incubation temperature, compared to control females. However, the overall incubation attentiveness experienced by clutches did not differ between treatments due to complete compensation by the partners of inbred females. This is perhaps why there was no significant decline in either hatching success or hatching mass of offspring cross fostered to inbred females. In chapter four I examined the effects of inbreeding on resting metabolic rate by measuring resting oxygen consumption (VO2) of inbred females compared to control females. Resting VO2 (corrected for body size) was higher in inbred compared to control females. Inbred females also showed increased central organ mass (heart plus liver) for their body size compared to control females. Resting VO2 (corrected for body size) was positively was correlated with central organ mass (corrected for body size) and negatively correlated with peripheral organ mass (corrected for body size). I also found a positive correlation between resting VO2 and the ability to evade capture (rank capture order from a flight aviary). My results suggest that the reduced survival rates of the offspring of inbred females may be caused by reductions in maternal investment, since both egg size/quality and incubation attentiveness have previously been found to positively correlate with offspring viability. The finding that resting VO2 increased with inbreeding may suggest that inbred females showed reduced maternal investment in egg production and incubation attentiveness due to higher energetic costs of self-maintenance. Resting metabolic rate has been found to be associated with a wide range of life-history traits and so this finding could have important implications for the fitness of inbred animals. These findings are novel and shed light on the previous observations that maternal inbreeding can reduce early and long-term survival of the offspring of inbred individuals in wild populations.

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Haikola, Sari. "Inbreeding depression in the Glanville fritillary butterfly (Melitaea cinxia)." Helsinki : University of Helsinki, 2003. http://ethesis.helsinki.fi/julkaisut/mat/ekolo/vk/haikola/.

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Boakes, E. H. "An investigation of inbreeding depression and purging in captive populations." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596740.

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I use simulated pedigree and fitness data to test the statistical power of a regression model proposed by Ballou (J. Heredity, 88, 169-178, 1997) to detect inbreeding depression and purging. Finding the model to be lacking in power when used to analyse typical zoo pedigrees, I develop an alternative, more powerful model. I use both of these models to investigate the effects of inbreeding in 136 zoo populations, encompassing 109 species of mammals, birds, reptiles and amphibians. A significant cross-population trend in inbreeding depression is detected, as is a cross-population trend of purging in those populations which showed negative effects of inbreeding. The average change in inbreeding depression due to purging is < 2%, however, suggesting that fitness benefits are rarely appreciable. The study re-emphasises the necessity to avoid inbreeding in captive breeding programs and shows that purging cannot be relied upon to remove deleterious alleles from zoo populations. The severity of inbreeding depression appears to vary among taxa but few predictors of a population’s response to inbreeding are found. The models are most likely to detect inbreeding depression in large populations, i.e. in populations in which their statistical power is maximised. By analysing founders’ contributions to inbreeding, I find that random founder effects play a part in determining whether a population suffers from inbreeding depression. I also show that inbreeding depression may have differing effects on sexes but find no evidence of a consistent sex-bias. Susceptibility to inbreeding depression may therefore depend on a complex interaction of genetic, environmental and stochastic factors.

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Lloyd, Hywel ap Dafydd. "The dynamics of inbreeding depression in the butterfly Bicyclus anynana (Butler)." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426101.

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Zajitschek, Susanne Biological Earth &amp Environmental Sciences Faculty of Science UNSW. "The interplay between sexual selection, inbreeding and inbreeding avoidance in the guppy, Poecilia reticulata." Publisher:University of New South Wales. Biological, Earth & Environmental Sciences, 2008. http://handle.unsw.edu.au/1959.4/41218.

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Inbreeding can have profound negative effects on individuals by reducing fertility and viability. In populations, inbreeding depression can reduce growth rates and increases extinction risk. The aims of this thesis are to investigate inbreeding depression in male guppies (Poecilia reticulata) and to study the evolution of mechanisms for inbreeding avoidance in females, using guppies from a feral population in Queensland, Australia. Male guppies are highly polymorphic in their sexual ornamentation, indeed they show one of the most extreme polymorphisms observed in nature. Female guppies exhibit complex mate choice based on preferences for ornamentation, as well as social context. I aim is to examine how these factors of inbreeding avoidance alter sexual selection. In male guppies I found strong inbreeding depression in male sperm numbers, which is amplified under semi-natural compared to laboratory conditions (Chapter 2). Moreover, inbreeding depression results in low fertility under sperm competition: an experiment using artificial insemination techniques reveals that highly inbred males are heavily disadvantaged in gaining paternity (Chapter 3). On population level, inbreeding depression is manifest in reduced growth rates, predominantly in the early stages of inbreeding (Chapter 4). Population growth at inbreeding coefficients f=0.375-0.59 did not seem to lead to inbreeding depression, whereas lower levels of inbreeding reduced population growth. Although the growth rates in inbred populations appear normal, severe inbreeding depression is uncovered after outbred immigrants are added. Specifically, male immigrants are most efficient in short-term genetic rescue, probably due to insemination of large numbers of females whereas females are limited in the number of eggs they can produce (Chapter 4). Male ornamental traits show significant inbreeding depression in semi-natural conditions only (Chapters 2 & 3). Inbreeding avoidance mechanisms seem to have evolved in females: they prefer courtship displays of non-inbred males (Chapter 2), unfamiliar males (Chapter 5) and males with rare patterns (Chapter 6). This preference might increase the mating success of immigrants, and may have evolved to facilitate the avoidance of inbreeding. Together with context-independent preferences for ornament combinations (Chapter 6), it also offers an explanation for the maintenance of polymorphism in this species.

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Bellamy, L. A. R. "Sexual selection in stalk-eyed flies : inbreeding depression, sperm competition and larval development." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1347916/.

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Stalk-eyed flies (Diptera: Diopsidae) have emerged as an important model organism in the study of sexual selection. They are characterised by their eyes being located on elongated stalks that protrude from their heads. In many species, males have larger eyespans than females as a result of female mate preference and malemale competition. In this thesis, I investigated several different aspects of stalk-eyed fly biology. First, I provide a comprehensive review that asks whether the literature supports the hypothesis that male sexual traits suffer from heightend inbreeding depression relative to non-sexual traits. This is followed by an empirical study that examines how inbreeding affects a sexual trait (male eyespan) relative to non-sexual traits (female eyespan and male wing length) in the stalk-eyed fly Diasemopsis meigenii. Sexual selection theory predicts that sexual traits should suffer greater inbreeding depression than non-sexual traits. Full-sibling matings were used to generate highly inbred lines of D. meigenii. Over 11 generations of inbreeding, male eyespan suffered more from inbreeding depression than female eyespan and male wing length. After crossing inbred lines, male eyespan was restored more than male wing length, but not female eyespan. Next, I used a P2 mating design to test male offence and defence roles in sperm competition. Female D. meigenii were mated once by a ‘focal male’ and n times by a ‘competing male’ (where n = 1, 3 or 5). Male defence and male offence ability was assessed by mating the focal male either before or after the competing male. I found no evidence of sperm precedence in D. meigenii and suggest that the most likely mechanism of sperm competition is via mixing of sperm from rival males. Finally, I examine how adult sexual size dimorphism in the stalk-eyed fly Teleopsis dalmanni is determined and regulated during larval development.

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Kurian, Valsa. "Investigation on the genetic control of the Primula L. heteromorphy supergene." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294893.

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Daniels, Susan J. "Female Dispersal and Inbreeding in the Red-cockaded Woodpecker." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36971.

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Dispersal is a critical life-history component; it determines gene flow and has profound effects on population structure, demography, social systems, and population viability. To add to our knowledge of dispersal and, in particular, our understanding of the relationship between dispersal and inbreeding, I studied three aspects of the biology of the red-cockaded woodpecker: dispersal of breeding females; the costs, benefits, and frequency of inbreeding; and the effect of inbreeding on natal dispersal. Dispersal of breeding female red-cockaded woodpeckers is strongly associated with inbreeding avoidance and mate choice, weakly associated with site choice, and not found to be associated with social constraints. Estimates of mortality for non-dispersing and dispersing breeding females were 24 and 59 percent per year, respectively-rare evidence of the cost of breeding dispersal. Significant costs of close inbreeding were found. Closely related pairs (kinship coefficient greater than 0.1) had lower hatching success as well as lower survival and recruitment of fledglings than unrelated pairs. Moderately related pairs (kinship coefficient between 0 and 0.1) and moderately inbred individuals had increased hatching success, but did not produce more young. Despite documented costs of close inbreeding and a predictable spatial distribution of closely related males near the natal territory, female fledglings disperse a median of only two territories and a modal distance of one territory. Natal dispersal of females is affected by closely related males on the natal site but unaffected by closely related males or moderately related males that are off the natal site.
Master of Science

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Paiva, Renato Diógenes Macedo. "Endogamia em rebanhos de caprinos da raça Saanen." Universidade Federal Rural do Semi-Árido, 2016. http://bdtd.ufersa.edu.br:80/tede/handle/tede/583.

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The Saanen goat breed is present in all countries that have a fairly developed dairy goat and the predominant race in farms and with higher milk production average. The objective of this study was to evaluate the population structure and the effect of inbreeding on the production of milk up to 305 days of lactation and duration of lactation in Saanen goats belonging to participating flocks of Breeding Program of Dairy Goats (Capragene®). The evaluated population parameters were the effective number of founders (fe) and ancestors (fa), effective size (Ne), inbreeding coefficient (F), individual increase in inbreeding (ΔFi), average coefficient of relatedness (AR), the integrity of pedigrees and Wright's F statistics. The effect of inbreeding was verified by t test evaluating contrast through a subroutine MTDFREML application. We used pedigree data from 7,640 animals and 3,548 lactation information pertaining to 2,154 goats. The mean AR and F coefficients of the population were 1.48% and 0.78%, respectively. But the effective size was 39,69, from complete equivalent generation. The effective number of founder animals (fe) and ancestors (fa) was 123 and 101 respectively, and fiam all ancestors only 39 were responsible for explaining 50% of the genetic variability within the population, which indicates loss of source genes. As for the integrity of pedigrees were identified 80.13% animals as sires (breeders) and 79.02% as mothers. For subdivision of the population of the values obtained for FIS, FST and FIT were -0.017, 0.028 and 0.011 respectively, indicating the absence of the population structuring. There was no significant effect of inbreeding on the duration of lactation (P>0.05). The production of milk up to 305 days of lactation was significantly affected by inbreeding, with a reduction of 2.31 kg with the increase of 1% in the individual inbreeding
A raça de caprinos Saanen está presente em todos os países que têm uma caprinocultura leiteira razoavelmente desenvolvida, sendo a raça predominante nos criatórios e de maior média de produção de leite. Objetivou-se com este estudo avaliar a estrutura populacional e o efeito da endogamia sobre a produção de leite até os 305 dias de lactação e a duração da lactação em cabras da raça Saanen pertencentes a rebanhos participantes do Programa de Melhoramento Genético de Caprinos Leiteiros (Capragene®). Os parâmetros populacionais avaliados foram o número efetivo de fundadores (fe) e ancestrais (fa), tamanho efetivo (Ne), coeficiente de endogamia (F), incremento individual de endogamia (ΔFi), coeficiente médio de parentesco (AR), a integridade dos pedigrees e as estatísticas F de Wright. O efeito da endogamia foi verificado pelo teste t, avaliando-se contraste por meio de uma sub-rotina do aplicativo MTDFREML. Foram utilizados dados de pedigree de 7.640 animais e informações de 3.548 lactações pertencentes a 2.154 cabras. Os coeficientes de F e AR médios da população foram de 1,48% e 0,78%, respectivamente. Já o tamanho efetivo foi de 39,69, considerando a geração equivalente completa. O número efetivo de animais fundadores (fe) e de ancestrais (fa) foi de 123 e 101 respectivamente, o que indica perda de genes de origem. De todos os ancestrais, apenas 39 foram responsáveis por explicar 50% da variabilidade genética da população. Quanto à integridade dos pedigrees foram identificados 80,13% de animais como pais (reprodutores) e 79,02% como mães. As estatísticas F de Wright, FIS, FST e FIT, foram -0,017, 0,028 e 0,011 respectivamente, indicando a ausência de subestruturação da população. Não houve efeito significativo da endogamia sobre a duração da lactação (P>0,05). A produção de leite até os 305 dias de lactação foi afetada significativamente pela endogamia, havendo uma redução de 2,31 kg na produção de leite com o incremento de 1% na endogamia individual
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Rausch, Joseph Howard. "The evolution of selfing, inbreeding depression, and polyploidy in the Claytonia perfoliata complex (Portulacaceae)." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Dissertations/Spring2008/j_rausch_042508.pdf.

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Bucklin, Katherine Adelaide. "Analysis of the genetic basis of inbreeding depression in the Pacific oyster Crassostrea gigas /." Connect to Digital dissertations. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.

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Prata, Inês Azevedo. "Avaliação de um sistema de cruzamento de raças leiteiras : comparação de saúde, reprodução e produção entre vacas cruzadas e vacas de raça Holstein-frísia." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/14531.

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Dissertação de Mestrado Integrado em Medicina Veterinária
Ao longo das últimas décadas, a necessidade de produzir cada vez maiores quantidades de leite conduziu ao melhoramento da raça Holstein-Frísia, e à seleção dos animais no sentido de produzir mais leite por vaca. Esta seleção levou ao acasalamento cada vez mais frequente de animais aparentados; o elevado coeficiente de consanguinidade entre os animais desta raça resultou numa elevada depressão consanguínea que se manifesta sobretudo por um forte declínio nas características de adaptabilidade (ou fitness) dos animais, principalmente as de eficiência reprodutiva. O cruzamento rotativo de três raças tem-se tornado cada vez mais popular como estratégia para tentar diminuir os efeitos indesejáveis da consanguinidade. No presente trabalho, foram analisados dados de fêmeas Holstein-Frísia (H), Holstein x Montbéliarde (HM), e Holstein x Vermelha Sueca (HS), provenientes de 6 explorações portuguesas. Os dados analisados foram: intervalo entre partos (IEP), dias abertos (DA), número de inseminações artificiais necessárias para a conceção (Nº IA), dias em leite à primeira inseminação artificial (DEL 1ª IA), produção total ao longo da vida (PLV), produção média de leite por dia (PLD), percentagem de gordura e proteína no leite, contagem de células somáticas no leite (CCS), proporção de animais eliminados antes dos 305 dias da primeira lactação, e sobrevivência até ao parto seguinte. As cruzadas HM e as HS apresentaram IEP (p<0,01), DA (p<0,01) e DEL 1ª IA (p<0,05) inferiores às fêmeas Holstein. Não foram encontradas diferenças no Nº IA entre Holstein e HM (p=0,07) ou entre Holstein e HS (p=0,58). As fêmeas Holstein mostraram ser superiores às cruzadas na produção de leite, tanto na PLD (p<0,05) como na PLV (p<0,01). As vacas HS produziram leite com maior percentagem de gordura e de proteína que as vacas Holstein (p<0,05). Não foram encontradas diferenças na média de CCS entre vacas Holstein, HM e HS, em cada paridade. Nem as cruzadas HM (p=0,39) nem as cruzadas HS (p=0,30) diferem significativamente das Holstein puras na proporção de vacas eliminadas antes dos 305 dias da primeira lactação; Porém, uma maior proporção de vacas HM e HS parem pela terceira, quarta e quinta vez, em relação às vacas Holstein (p<0,05). Da comparação entre duas explorações, C e G (uma com animais descendentes deste cruzamento rotativo e outra cujo efetivo é de raça Holstein pura, respetivamente) destacam-se algumas diferenças, sendo as médias de IEP, DA e DEL 1ª IA ligeiramente inferiores na exploração C. Considerando os resultados do presente estudo, conclui-se que o cruzamento rotativo entre as raças Holstein-Frísia, Montbéliarde e Vermelha Sueca pode ser útil para diminuir o declínio reprodutivo das explorações leiteiras e melhorar a longevidade dos animais, pressupondo sempre um bom maneio reprodutivo e pesando sempre os benefícios obtidos contra o custo de uma possível descida na produção.
ABSTRACT - Evaluation of a Crossbreeding system for dairy cattle – Comparison of health, reproduction and production traits between pure Holstein cows and Holstein crosses - Over the last few decades, the need to produce progressively larger volumes of milk led to the genetic improvement of the Holstein-Frisian breed by selecting animals with the goal of producing more milk per cow. These efforts led to the frequent mating of related individuals. The increased inbreeding levels amongst the animals of this breed resulted in inbreeding depression, which translates mainly into the decline of certain fitness traits, especially the ones related to reproductive efficiency. The three-breed rotational crossbreeding system has become increasingly popular as a strategy to try to lessen the undesirable effects of inbreeding. In the present study data from Holstein-Frisian cows (H) and their crossings with the Montbéliarde (HM) and the Swedish Red (HS) breeds were analyzed. The animals were from 6 Portuguese dairy herds. The traits analyzed were: calving interval (CI), days open (DO), number of services per conception (NSC), days to first breeding (DFB), total lifetime production (LP), average daily milk yield (DMY), milk protein and fat percentage, somatic cell score (SCS), proportion of animals eliminated before 305 days of first lactation, and survival to subsequent calving. The HM and HS crossings had lower CI (p<0,01), DO (p<0,01) and DFB (p<0,05) when compared to pure Holsteins. No significant differences in NAI were found between Holsteins and HM cows (p=0,07) or between Holsteins and HS cows (p=0,58). Holstein females were superior to both crossings regarding not only DMY (p<0,005) but also LP (p<0,01). HS crossbreds produced milk with higher fat content and also protein content than pure Holstein cows (p<0,05). No differences were noted in the average SCS between pure Holsteins, HM and HS cows with similar parities. Neither HM crossbreds (p=0,39) or HS crossbreds (p=0,30) had significant differences regarding the number of cows that left the herd before 305 days of the first lactation. However, a higher percentage of HM and HS cows survived to calve a third, fourth and fifth time when compared to pure Holstein cows (p<0,05). From the comparison between two herds, C and G (one that applies this crossbreeding system and one where all animals are pure Holsteins, respectively) one can highlight certain differences given that CI, DO and DFB averages were slightly lower in herd C. Considering the results of this study one can conclude that the three-breed crossbreeding system that includes the Holstein, Montbéliarde and Swedish-Red breeds can be a useful tool to soften the decline in reproductive health witnessed in dairy herds and to improve the survival of dairy cattle. This assuming of course that a sound reproductive management protocol is established and weighting the gain in reproductive health, total milk solids and survival against a possible drop in milk production.
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Mamani, Gerardo Cornelio Mamani. "Associação entre coeficientes de endogamia estimados por diferentes métodos e características produtivas em bovinos Nelore e ovinos Santa Inês." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/74/74135/tde-13022019-105628/.

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O monitoramento da endogamia é fundamental para o estabelecimento de um programa de melhoramento animal. Os coeficientes de endogamia foram estimados a partir de segmentos de homozigose (FROH), matriz de parentesco genômico com frequências alélicas derivadas dos dados (FGRM), frequências alélicas ajustadas a 0,5 (FGRM05), excesso de homozigose (FHOM) e informação de pedigree (FPED) em bovinos Nelore e ovelhas Santa Inês. Os dados genotípicos para a população Nelore foram obtidos de 2.569 animais utilizando um painel de 725,293 polimorfismos de nucleotídeo único e um pedigree composto por 15.846 indivíduos. Para a população de ovinos Santa Inês, 576 animais foram genotipados para 47.033 polimorfismos de nucleotídeo único, juntamente com dados de pedigree de 32.266 indivíduos. Picos notáveis nos cromossomos 7, 12 e 21 dos bovinos e no cromossomo 16 das ovelhas, representavam ilhas de ROH (> 47%), destacando regiões possivelmente afetadas pela pressão seletiva. Os valores médios para FPED, FROH, FGRM e FGRM05 foram 0,005, 0,058, -0,007 e 0,40, respectivamente no caso do Nelore, enquanto valores medias de 0,32, 0,049, 0,015, 0,287 e 0,015 para FPED, FROH, FGRM, FGRM05 e FHOM, respectivamente no caso das ovelhas. Esses coeficientes de endogamia foram associados negativamente com peso ao nascer, peso à desmama, ganho de peso pós-desmame, escore de muscularidade, precocidade, conformação e circunferência escrotal em bovinos Nelore e para todas as características analisadas em Santa Inês. Também foi encontrada uma correlação negativa entre depressão endogâmica e estimativas de variâncias genômicas de dominância variando de -0,35 a -0,98 para Nelore e -0,89 a -0,91 para ovinos Santa Inês. Nós afirmamos que as descobertas relatadas podem ser usadas para manter a diversidade genética em bovinos Nelore e ovelhas Santa Inês sob uma perspectiva genômica.
Monitoring inbreeding is critical for establishing a sustainable breeding program. Inbreeding coefficients were estimated from runs of homozygosity (FROH), genomic relationship matrices coupled with allele frequencies derived from data (FGRM), allele frequencies set to 0.5 (FGRM05), excess of homozygosity (FHOM), and pedigree information (FPED) from Nellore cattle and Santa Ines populations. Genotypic data for the Nellore population were obtained from 2,803 animals using a panel of 725, 293 single-nucleotide polymorphisms and a pedigree consisting of 15,846 individuals. For the Santa Ines sheep population 576 animals were genotyped for 47,033 single-nucleotide polymorphisms along with pedigree data of 32,266 individuals. In cattle noticeable peaks on chromosome 7, 12, and 21, and in sheep on chromosome 16, represented hotspots of autozygosity (> 47%), highlighting putative regions affected by selective pressure. The mean values for FPED, FROH, FGRM, and FGRM05 were 0.005, 0.058, -0.007, and 0.40, respectively for Nellore, while for Santa Ines were 0.32, 0.049, 0.015, 0.287 and 0.015 for FPED, FROH, FGRM, FGRM05 and FHOM, respectively. These inbreeding coefficients were negatively associated with birth weight, weaning weight, post-weaning weight gain, muscularity score, finishing score, conformation score, and scrotal circumference on Nellore and for all traits analyzed on Santa Ines. Also, a negative correlation was found between inbreeding depression and estimates of dominance genomic variances ranging from -0.35 to -0.98 for Nellore and -0.89 to -0.91 for Santa Ines sheep. We contend that the findings reported here can be used to maintain genetic diversity in Nellore cattle and Santa Ines sheep from a genomic perspective.

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Nilsson, Emelie. "Investigation of pollen limitation, inbreeding and outbreeding depression and heterosis in Euphrasia stricta var. suecica on Gotland." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-346597.

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Habitat fragmentation is one of the main threats to semi-natural grasslands all over Europe, causing reductions in both numbers of populations and numbers of individuals withinpopulations. Small isolated populations are particularly vulnerable to fluctuations that reducespopulation size and could lead to loss of genetic variation due to inbreeding depression, orfixation of harmful alleles due to genetic drift. The aim of this study was to investigate if thecritically endangered eyebright Euphrasia stricta var. suecica experiences pollen limitation,inbreeding depression and heterosis or outbreeding depression. Low pollen limitation waspredicted as well as low inbreeding depression due to high selfing rate. Outbreedingdepression or heterosis was expected based on previous studies indicating strong geneticdifferentiation among populations. This study was conducted in two traditionally managedmeadows in the central part of Gotland, Sweden, using supplemental hand-pollinations andcontrolled crosses. Individuals were collected when the flowering period was over and seedswere counted and weighed. There were no signs of either pollen limitation, inbreedingdepression, heterosis or outbreeding depression in any of the two wooded hay meadows. Thedegree of autonomous selfing was high, indicating that E. stricta var. suecica is not dependenton pollinators for seed production. A significant difference between the meadows was foundin proportion of viable seeds. As there were no signs of local adaptation, individuals could betranslocated between the two studied populations or seed sowings could be used to increasepopulation size. However, before such conservation efforts are undertaken, it is important toconduct further studies that investigate several populations including more life-stages.

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Tino, Camila Renata de Souza. "Estrutura populacional e análise de variabilidade genética em rebanhos ovinos brasileiros." Dracena, 2016. http://hdl.handle.net/11449/138932.

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Orientador: Ricardo da Fonseca
Resumo: As raças ovinas deslanadas são parte do patrimônio genético do Brasil, formado por animais adaptados ao semiárido nordestino e com potencial de produção de carne e pele. No entanto tratam-se de raças de recente formação, ainda com poucos programas de melhoramento genético, e consequentemente, carente de estudos da estrutura populacional, variabilidade genética, endogamia e grau de conservação. Diante disso este trabalho teve dois objetivos: 1) analisar a variabilidade genética da raça Santa Inês no Brasil com base em informações de pedigree utilizando registros de animais da raça Santa Inês, provenientes da Associação Sergipana de Criadores de Caprinos e Ovinos (ASCCO) criados na Região Nordeste do Brasil e 2) avaliar a estrutura genética e variabilidade genética do núcleo de conservação da Embrapa Caprinos e Ovinos, localizada na cidade de Sobral, região do norte do estado do Ceará, controlado pelo Sistema de Gerenciamento de rebanho (SGR) dentro do dentro do programa de melhoramento genético de caprinos e ovinos de corte – GENECOC®. O arquivo de pedigree da raça Santa Inês (ASCCO) continha 29080 animais e os arquivos de dados genealógicos pertencentes ao GENECOC 904 indivíduos da raça Santa Inês, 972 indivíduos da raça Somalis e 1372 indivíduos da raça Morada Nova. Para a primeira análise dos animais Santa Inês a média da integridade do pedigree nas últimas quatro gerações foi maior que 50% e o número de gerações completas equivalente foi igual a 4,89. O valor do coeficient... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The wooless sheep breeds are part of the genetic heritage of Brazil, formed by animals highly adapted to semi-arid Northeast and high capacity of production of meat and skin. However it is of recent formation breeds, still few breeding programs, and consequently lacking in studies of population structure, genetic variability, inbreeding and degree of conservation. Therefore this study had two objectives: 1) to analyze the genetic variability of Santa Ines in Brazil based on pedigree information using animal records Santa Ines, from the Goat Breeders of Sergipana Association and Sheep (ASCCO) created in Northeast of Brazil and 2) evaluate the genetic structure and genetic variability conservation nucleus of Embrapa goats and sheep, located in Sobral, northern region of the state of Ceará, compiled by Management System for Livestock, part of the within the Breeding Program of Goats and sheep - GENECOC® . Santa Inês breed pedigree file (ASCCO) contained 29080 animals and genealogical data files belonging to GENECOC 904 individuals Santa Ines, 972 individuals of Somalis breed and 1372 individuals of Morada Nova breed. For the first analysis of animal Santa Inês the average pedigree integrity in the last four generations was greater than 50% and the number of full generations equivalent was equal to 4.89. The value of endogamic coefficient (F) was 0.32% and the obtained relationship coefficient was 3.1%. The generation interval was 5.75 years. For the results of the parameters bas... (Complete abstract click electronic access below)
Mestre

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Szulkin, Marta. "Inbreeding and its avoidance in a wild bird population." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:25e95465-f4ab-43ce-92e2-9d7fe88efeef.

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Inbreeding occurs when relatives mate and have offspring. Inbreeding depression is hypothesized to have influenced the evolution of mating systems and behavioural mechanisms of inbreeding avoidance in the animal kingdom. Inbreeding in the wild is difficult to measure, as in order to build a pedigree allowing us to identify matings between relatives, the identity of as many as possible members of a population needs to be known. For a long time, the main source of knowledge about inbreeding depression was based on laboratory and agricultural studies, which did not reflect the array of environmental pressures wild populations have to cope with. In consequence, the deleterious consequences of inbreeding have often been underestimated. This is problematic because accurate estimates of the effect size of inbreeding depression are needed to study the strength of selection on inbreeding avoidance mechanisms, and are also of importance to conservation genetics. The aim of this thesis was to use pedigree data to infer the occurrence and effects of inbreeding using over forty years of breeding events of the great tit Parus major from Wytham Woods, Oxfordshire. The effects of inbreeding on fitness were investigated across a life-history continuum, and across environments. I found that close inbreeding (f=0.25) resulted in pronounced inbreeding depression, which acted independently on hatching success, fledging success, and recruitment success, and reduced the number of fledged grand-offspring by 55%. My results therefore suggest that estimates of fitness costs of inbreeding must focus on the entire life cycle. I also show that the variation in the strength of inbreeding depression varies across environments, particularly so the more the environmental variable considered is linked to fitness. These results emphasise the need of using relevant environmental contrasts when investigating inbreeding by environment interactions. I further asked whether individuals involved in matings with relatives differed relative to individuals mating with unrelated partners. I did not find any evidence for clear predictors of inbreeding, and I show that inbreeding depression in our population is entirely independent of any tendency for low quality parental genotypes, or phenotypes, to inbreed. Neither did I find any evidence for active inbreeding avoidance: great tits did not mate less often with kin than expected based on several scenarios of random mating, nor did I find increased rates of extra-pair paternity among birds breeding with relatives. In fact, I observed quite the contrary, as birds mating with kin exhibited a higher than average rate of close inbreeding relative to all scenarios of random mating investigated, showed lower rates of extra-pair paternity and divorce than birds mated to unrelated partners. I hypothesise that cases of occasional inbreeding in this population may result from mis-imprinting or a related process whereby some birds develop particularly strong bonds that are at odds with all predictions of avoiding inbreeding. Finally, I asked to what extent natal dispersal, a behaviour that is often hypothesized to play an important role in avoiding inbreeding, indeed reduces the likelihood of inbreeding. I found that male and female individuals breeding with a relative dispersed over several-fold shorter distances than those outbreeding. This led to a 3.4 fold increase (2.3-5, 95% CI) in the likelihood of close inbreeding relative to the population average when individuals dispersed less than 200m. This thesis demonstrates that inbreeding has deleterious effects on a wild population of birds, occurring throughout an individual’s life, and is of varying strength across environments. My findings strongly support the theory that natal dispersal should be considered as a mechanism of prime importance for inbreeding avoidance.

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Gooley, Rebecca May. "Using genetic data to understand how fitness in captivity translates to fitness in the wild: a Tasmanian devil case study." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/19400.

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Threatened species persisting in fragmented and declining populations are susceptible to increased inbreeding and a reduction in genetic diversity. Conservation management can involve in situ practices in the species’ natural habitat, and ex situ practices such as managing insurance populations. In this study, I examined two components of conservation management; (1) the consequences of inbreeding on fitness in captivity, and (2) the consequences of inbreeding on fitness in the wild. I used the Tasmanian devil as a model species. The Tasmanian devil is facing extinction due to the emergence of a contagious cancer, devil facial tumour disease. To ensure survival of the species an insurance population was established in 2006 to be used as a source population for re-wilding. I discovered significant variation in inbreeding across individuals in the Tasmanian devil insurance population, but surprisingly found this variation had no influence on individual fitness. I proposed that the benign environment in captivity can weaken the severity of inbreeding on fitness. In the wild I showed that Tasmanian devils were experiencing significant inbreeding depression, which is manifested as a decline in female reproductive success. This is in direct contrast to the captive population that did not experience breeding declines in the face of inbreeding. These observations support the hypothesis that the severity of inbreeding on fitness may not accurately be measured in captive populations. This work has provided new information about inbreeding in captive and wild Tasmanian devils, as well as new insights into the interaction between environment, inbreeding and fitness. The research I have carried out on the Tasmanian devil insurance population has allowed me to make recommendations to conservation managers that will help optimise the fitness of captive Tasmanian devils to sustain a genetically healthy population as a source for re-wilding projects.

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Isidro, Cristóbal Helsi María [UNESP]. "Depressão endogâmica em características de crescimento e resistência a Piscirickettsia salmonis em salmão coho (Oncorhynchus kisutch)." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/152017.

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Consejo Nacional de Ciencia y Tecnología (CONACYT)
Os programas de melhoramento em espécies aquícolas apresentam, no geral, um número restrito de famílias e um pequeno tamanho efetivo populacional, levando ao acasalamento de animais aparentados e, consequentemente, ao aumento da endogamia. Por sua vez, maiores níveis de endogamia tendem a ocasionar queda no desempenho dos animais causada pela depressão endogâmica. O objetivo deste estudo foi estimar os níveis de endogamia e depressão endogâmica sobre as características de peso à despesca, comprimento à despesca e resistência a Piscirickettsia salmonis em uma população de salmão coho. A resistência a Piscirickettsia salmonis foi definida como o dia da morte de cada peixe após desafio conduzido em dois anos, com média de 42 dias em 2012 e 14 dias no ano de 2014. Foi utilizado um banco de dados composto por 53.504 observações, provenientes de nove gerações e 930 famílias. A estimação dos componentes de variância e endogamia foram obtidas utilizando o programa computacional AIREMLF90 e os valores de depressão endogâmica foram estimados a partir de um modelo animal. Os valores observados para o coeficiente de endogamia foram crescentes ao longo das gerações, com uma taxa média máxima de 8,75% no ano de 2014. A depressão endogâmica afetou em maior nível as características de peso à despesca e dia de morte, com redução de 6,4 e 9,2% no desempenho dos animais, respectivamente, para o nível máximo de endogamia observado (30%). Os resultados indicam a necessidade de uso de estratégias mais efetivas de controle da endogamia para a manutenção do progresso genético do programa de melhoramento de salmão coho.
Aquaculture breeding programs present, in general, low number of families and reduced effective population size, resulting in mating of related animals and, consequently, increased level of inbreeding. High inbreeding coefficient may negatively impact the animals’ performance due to inbreeding depression. The objective of this study was to estimate inbreeding coefficient and inbreeding depression on growth traits and resistance against Piscirickettsia salmonis in a coho salmon population. Resistance against P. salmonis was defined as days to death of each fish after being challenged in two different years, with an average of 42 days in 2012 and 14 days in 2014. Data of 53,504 animals from 930 families was analyzed. Variance components were estimated using the software AIREMLF90, and inbreeding depression was estimated under an animal model. An increasing rate of inbreeding was observed, attaining an average of 8.75% in 2014. Inbreeding depression was more pronounced for harvest weight (PD) and days to death (DM), in comparison with harvest length. At the highest observed inbreeding level (30%), the estimated reduction caused by inbreeding depression was equal to 6,4% for PD and 9,2% for DM. The results indicate the necessity to control inbreeding more effectively for the studied coho salmon population, to guarantee genetic progress in the long term.
CONACYT: 579741/410470

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Hammerly, Susan C. "The Effects of Inbreeding on Fitness Traits in the Critically Endangered Attwater’s Prairie-chicken." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699930/.

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The goals of captive breeding programs for endangered species include preserving genetic diversity and avoiding inbreeding. Typically this is accomplished by minimizing population mean kinship; however, this approach becomes less effective when errors in the pedigree exist and may result in inbreeding depression, or reduced survival. Here, both pedigree- and DNA-based methods were used to assess inbreeding depression in the critically endangered Attwater’s prairie-chicken (Tympanuchus cupido attwateri). Less variation in the pedigree-based inbreeding coefficients and parental relatedness values were observed compared to DNA-based measures suggesting that errors exist in the pedigree. Further, chicks identified with high parental DNA-based relatedness exhibited decreased survival at both 14- and 50-days post-hatch. A similar pattern was observed in later life stages (> 50 days post-hatch) with birds released to the wild; however, the pattern varied depending on the time post-release. While DNA-based inbreeding coefficient was positively correlated with mortality to one month post-release, an opposite pattern was observed at nine months suggesting purging of deleterious alleles. I also investigated whether immunocompetence, or the ability to produce a normal immune response, was correlated with survival; however, no significant correlation was observed suggesting that inbreeding was a more important factor influencing survival. Pairing individuals for breeding by minimizing DNA-based parental relatedness values resulted in a significant increase in chick survival. This study highlights the importance of using DNA-based methods to avoid inbreeding depression when errors exist in the pedigree.

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Klips, Robert A. "Inbreeding depression, autonomous self-pollination, and the genetic affinities of a rare taxon within the rose-mallows, Hibiscus section Muenchhusia /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487862399447942.

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Herrera, Rios Ana Cristina. "Genome scan for homozygosity islands and inbreeding effect on reproductive traits in nelore beef cattle." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/155941.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O uso intensivo de biotecnologias reprodutivas tem feito com que se eleve a taxa de nascimento de progênies com maior grau de parentesco (maior taxa de nascimento de meio-irmãos e irmãos completos). Assim, o conhecimento sobre o coeficiente da endogamia média do rebanho torna-se relevante para a eficiência do sistema de produção. Com o advento da genômica, o coeficiente de endogamia (F) pode ser estimado com base na informação de milhares de marcadores do tipo polimorfismos de base única (SNPs), espalhados por todo o genoma. No presente estudo, informações de 3.785 animais da raça Nelore (1,760 machos e 2,025 fêmeas) genotipados para 777.962 SNPs do BovineHD BeadChip (Illumina Inc., San Diego, CA, USA) foram utilizadas com o objetivo de avaliar a taxa de endogamia em rebanhos comerciais da raça Nelore, bem como investigar o seu efeito (depressão endogâmica) sobre a expressão fenotípica de características reprodutivas (idade ao primeiro parto (IPP), ocorrência de prenhez precoce (OPP) e reconcepcão de novilhas (REC)). A estimativa do valor de F, bem como da depressão endogâmica, foi feita utilizando diferentes metodologias: (i) matriz de parentesco genômica com frequências alélicas obtidas da população base (FG); (ii) matriz de parentesco genômica com frequências alélicas fixadas em 0,5 (FGRM); (iii) com base no excesso de SNPs em homozigose (FSNP); e (iv) corrida de homosigose (FROH). Os resultados da corrida de homosigose também foram utilizados para identificar os padrões (tamanho e distribuição) dos segmentos ROH na raça Nelore bem como para identificar ilhas de homosigose (segmentos ROH compartilhados por mais de 50% da população). Foram identificados 210.636 segmentos ROH distribuídos nos 29 autossomos e cinco ilhas de homozigose localizadas nos cromossomos 5, 7, 12, 21 e 26, nas quais 43 genes foram identificados. Alguns destes genes (INHBE, INHBC, STAT6, FGF8 e DPCD) foram previamente associados com caracteristicas reproductivas, de crescimento, resposta inmume e adaptabilidade em bovinos. As médias para o coeficiente de endogamia calculado com base nas diferentes abordagens foram: -0,0006 (FG), 0,4376 (FGRM), 0,5500 (FSNP) e 0,0590 (FROH). As correlações foram ente baixas FG-FSNP (-0,28), FG-FGRM (-0,20), FG-FROH (0,21), a moderadas FROH-FSNP (0,68), FROH-FGRM (0,72) e fortemente alta para FSNP-FGRM (0,99). O valor médio de F variou de acordo com a metodologia utilizada. O valor extremamente alto do FSNP denota que este método tende a superestimar as taxas de endogamia. Independentemente do método utilizado para obter os valores de F, foi verificado que o aumento de 1% no coeficiente de endogamia médio do rebanho influenciou desfavoravelmente a média das características reprodutivas avaliadas.
The intensive use of reproductive biotechnologies has increased the birth rate of progenies with high degree of relationships (higher birth rate of half- and full-sibs). Thus, the control of herd inbreeding becomes relevant for the efficiency of the production system. With genomics, the inbreeding coefficient can be estimated using thousands of single nucleotide polymorphisms (SNPs), spread throughout the genome. In the present study, information of 3,785 Nelore animals (1,760 males and 2,025 females) genotyped with 777,962 SNP markers of BovineHD BeadChip (Illumina Inc., San Diego, CA, USA) was used with the objective of evaluating the inbreeding rates of Nelore commercial herds, as well as to investigate the effects of inbreeding (inbreeding depression) on the phenotypic expression of reproductive traits (age at first calving (AFC), heifer early pregnancy (EP), and heifer rebreeding (HR)). The inbreeding coefficient (F) and inbreeding depression were estimated based on (i) genomic relationship matrix considering allele frequencies estimated from the base population (FG); (ii) genomic relationship matrix considering allele frequencies fixed at 0.5 (FGRM); (iii) excess of homozygous SNPs (FSNP); and (iv) runs of homozygosity (FROH). The runs of homozygosity results were also used to identify the pattern (size and distribution) of ROH segments as well as to identify ROH islands (ROH segments shared by more than 50% of the population). In total, there were identified 210,636 ROH segments and five ROH Islands located on the chromosomes 5, 7, 12, 21 and 26, in which 43 annotated genes were identified. Some of these genes (INHBE, INHBC, STAT6, FGF8 and DPCD) were previously associated with reproduction and growth traits, inmume response and adaptability in cattle. The average inbreeding calculated based on different approaches were -0.0006 (FG), 0.4376 (FGRM), 0.5500 (FSNP) e 0.0590 (FROH). These correlations ranged from low FG-FSNP (-0.28), FG-FGRM (-0.20), FG-FROH (0.21), to moderated FROH-FSNP (0.68), FROH-FGRM (0.72) and extremely high FSNP-FGRM (0.99). The average population inbreeding coefficient ranged according to the method used. The extremely high value of FSNP indicates that this approach tend to overestimate the inbreeding rates. Independently of the method used to obtain the F values, it was verified that the increase of 1% in the average herd inbreeding unfavorably influenced the mean value of the evaluated reproductive traits.
FAPESP#2009/16118-5

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Chiucchi, James Ernest Jr. "Genetic Diversity, Inbreeding and Diet Variation in an Endangered Rattlesnake, the Eastern Massasauga (Sistrurus c. catenatus)." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316110529.

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Laws, Rebecca, and n/a. "The causes of nest failure and effects of inbreeding depression in a historically small population of New Zealand Stewart Island robins." University of Otago. Department of Zoology, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090813.114240.

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Inbreeding depression is one of the factors that can increase the risk of extinction of small populations, and therefore understanding its effects is currently an important issue in conservation biology. Until recently, few studies on inbreeding depression were carried out in wild populations. These recent studies have highlighted the variability in detecting inbreeding depression among natural populations and the multitude of factors that can influence its expression. Many of the factors affecting inbreeding depression in wild populations remain largely unexplored and most of the recent studies in this area have tended to focus on incidents of inbreeding in populations with a history of large population size. The aim of this study is to investigate the relative importance inbreeding depression has had on individual fitness parameters in a population of New Zealand's Stewart Island robins Petroica australis rakiura introduced to Ulva Island. This island population has historically gone through several population bottlenecks. Four main factors that potentially influence the rate of inbreeding and the extent of inbreeding depression, were investigated: environmental variability, life history stage, genetic load and dispersal. Generalized Linear Mixed Modelling was first used to determine how weather affected nest survival. Weather effects were then incorporated into models containing demographic factors to control for environmental variability, and finally parental, maternal and paternal inbreeding co-efficients (=f) were added to models to determine the relative importance of inbreeding depression. Interactions between inbreeding depression and environmental factors were explored. Three different life history stages were compared to determine the differences in inbreeding depression at each stage as well as cumulative effects over time. The genetic load of the population was estimated using lethal equivalents allowing for standardised comparison of inbreeding depression with other species. The likelihood of inbreeding in the population was also explored by investigating the factors affecting dispersal patterns and evaluating evidence for inbreeding avoidance. Inbreeding depression was found to be mild in the robin population. Weather did not have strong effects on nest survival or interactions with inbreeding. Female age was the only factor interacting with inbreeding, with younger inbred females experiencing significantly reduced offspring juvenile survival. Parental and paternal f did not significantly affect brood survival at any life history stage, however, maternal f showed significant effects on nest juvenile survival with the strongest effect occurring when survival was examined cumulatively over all life history stages. The Stewart Island robin had a relatively low lethal equivalent value compared to the closely related North Island robin and other avian species. This difference was associated with the Stewart Island robin having a low genetic load, most likely due to historical genetic purging during periods of population bottleneck. The Ulva Island robin population did not appear to be avoiding inbreeding through dispersal. Dispersal distance was most strongly influenced by the location of the natal nest of the dispersing offspring. In conclusion, the genetic history of the population was likely to have had the strongest impact on the severity of inbreeding depression in the Ulva Island robin population. The results of the thesis highlight the need to examine a number of factors to be able to explain variability in inbreeding depression among populations.

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25

Zu, Pengjuan. "Effects of Nectar Production and Pollinator Assemblies on Mating Patterns in Orchids." Thesis, Uppsala universitet, Växtekologi och evolution, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159358.

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Pollinator visitation patterns should affect pollination success and mating patterns in flowering species. In the orchid family, about one third of the species do not provide any reward for their pollinators. Pollination by deceit is typically associated with low fruit set but may increase the chance of cross-pollination since the pollinator should soon leave the individual plant when there is no reward in the flowers. This may be beneficial if self-fertilisation results in inbreeding depression. I studied the mating patterns of one rewarding and one deceptive orchid in two closely related genera by tracking the fate of stained pollinia. I also conducted controlled crosses to estimate inbreeding depression. The results show that the deceptive orchid Dactylorhiza lapponica has lower pollination success, but higher cross-pollination rate (ca. 90%) than the nectariferous orchid Gymnadenia conopsea (ca. 18% cross-pollination). The results further suggest that in G. conopsea, nocturnal visitors mediate higher geitonogamous pollination rate (ca. 100%) than diurnal visitors (ca. 60%). In both study species, fruits produced from cross-pollination were heavier than fruits produced from selfing. Inbreeding depression for fruit mass did not differ significantly between the two species (δ = 0.21 in D. lapponica and δ = 0.29 in G. conopsea). These data support the hypothesis that pollination by deceit can enhance cross-pollination. A literature study including several rewarding and non-rewarding orchid species indicated lower geitonogamy in the deceptive orchids, but the difference was not statistically significant.

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Johnson, Collin Hauer. "Self-fertilization, Larval Dispersal, and Population Structure in the Marine Bryozoan Bugula stolonifera." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10180.

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Although the process by which fertilization occurs in bryozoans is well described, the ability to self-fertilize and the subsequent ecological consequences are poorly understood. Culturing experiments were conducted examining the effects of selfing on offspring survival and reproduction in the simultaneous hermaphrodite Bugula stolonifera collected from Eel Pond, Woods Hole, MA. Results from these experiments document significant decreases in survival and fecundity of selfed offspring, compared to outcrossed controls, suggesting that these animals are not routinely self-fertilizing in Eel Pond. How these arborescent colonies minimize selfing remains unclear, but it is hypothesized that conspecific aggregations could serve to minimize the chances that a colony utilizes its own sperm for fertilization. The genetic composition of these aggregations was investigated using a newly developed microsatellite library. As larvae routinely metamorphose on conspecific colonies, the possibility that larvae select or avoid their maternal colony was also investigated. Analyses of genetic structure document homogeneity throughout these aggregations on extremely small spatial scales, suggesting high amounts of larval dispersal within aggregations. When combined with results from parentage-exclusion and kinship analyses, these results indicate that a colony's nearest neighbors are not composed of siblings, potentially minimizing inbreeding. Molecular analyses were then used to determine if the high larval dispersal within aggregations resulted in high mixing between aggregations. Sites within Eel Pond separated by 100-300 m were routinely sampled from 2009 to 2011, and analyses were conducted to investigate potential inter- and intra-annual genotypic differentiation within and between aggregations. Results document that although low levels of mixing could result in increased homogeneity between some aggregations, barriers to genetic exchange prevent mixing between most sites. Further, inter-annual comparisons within sites document that significant differentiation can occur between reproductive seasons. Hence, any potential homogeneity achieved between sites during one reproductive season will likely be lost by the beginning of the next reproductive season. Additionally, while sampling in Eel Pond in 2010, I document the first occurrence from the western Atlantic Ocean of another aggregating arborescent bryozoan, Tricellaria inopinata. The growth and reproductive biology of these animals was monitored throughout 2011; results suggest that this introduction is likely to persist.

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27

Nuortila, C. (Carolin). "Constraints on sexual reproduction and seed set in Vaccinium and Campanula." Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514285004.

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Abstract Plant reproductive success is affected by a number of factors, such as climatic conditions and plant resource status during flowering and fruiting, and pollen origin in fertilization. In the present thesis project, different aspects of plant reproductive ecology were investigated in order to identify constraints on sexual reproduction and seed set in two clonal dwarf shrubs (Vaccinium myrtillus and V. vitis-idaea) and one long-lived perennial herb (Campanula rotundifolia). The work comprised phenological observations and experiments with the clonal shrubs at natural boreal forest sites in the Oulanka National Park in northern Finland. The impact of mycorrhiza on C. rotundifolia fitness traits was tested in hand pollinations in a greenhouse experiment. Pollen origin had some effect on fruit set, and had strong effects on the number of matured seeds in all three species. Seed yield reductions upon hand self-pollination as compared with hand cross-pollination were attributed to inbreeding depression in V. myrtillus, and presumably to partial self-incompatibility in C. rotundifolia. V. myrtillus and V. vitis-idaea showed a population structure where the number of matured seeds per fruit increased with increasing distance between pollen donor and pollen recipient. Clonal growth in concert with the foraging behaviour of bumblebee pollinators is thought to cause the possibility of either uniparental or biparental inbreeding, with a strong effect on the number of matured seeds per berry. In a flower-removal experiment lasting three years, costs of fruiting to future fecundity and vegetative traits were observed, but not to future survival in V. vitis-idaea and V. myrtillus. The response was more pronounced in the evergreen than in the deciduous species. In Campanula rotundifolia, mycorrhiza was associated with a cost to the plants' reproductive effort, as plant biomass and the number of flowers produced per plant were decreased in mycorrhizal plants in comparison with non-mycorrhizal plants. There was no difference in seed number, seed weight or germination between the seeds of mycorrhizal and non-mycorrhizal plants. However, the offspring of mycorrhizal plants had a higher relative growth rate, while also having a higher seed phosphorus concentration. In summary, sexual reproduction was variably constrained by previous reproduction in Vaccinium, and contrary to expectations, by mycorrhiza in Campanula. However, mycorrhiza had positive effects on some measures of offspring fitness. In all three species, self-pollination limited seed production.

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28

Rosvall, Ola. "Enhancing gain from long-term forest tree breeding while conserving genetic diversity /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5643-6.pdf.

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29

Kubota, Thaisa Yuriko Kuboyama [UNESP]. "Study of flow and contemporary pollen dispersal, mating system, spatial distribution of genotypes and inbreeding depression in fragmented population Cariniana estrellensis (Raddi) Kuntze, using microsatellite loci." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150019.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae), popularmente conhecida como jequitibá-branco, é uma espécie arbórea tropical típica de estágios sucessionais avançados, característica de florestas clímax. Apesar da sua importância ecológica, a espécie encontra-se ameaçada de extinção, principalmente devido à intensa exploração e degradação de seu ambiente natural. O objetivo deste trabalho foi investigar a diversidade genética, a estrutura genética espacial intrapopulacional (EGE), o sistema de cruzamento e o fluxo gênico contemporâneo de uma população de C. estrellensis, localizada em um fragmento florestal (448,2 ha) na cidade de Bataguassu (Estado do Mato Grosso do Sul, Brasil), utilizando marcadores microssatélites. Foram mapeadas, medidas (altura e diâmetro a altura do peito) e genotipadas todas as 285 árvores adultas encontradas na área e coletadas sementes de 20 árvores matrizes, 32 sementes por árvore para as análises de forma hierárquica dentro e entre frutos. Utilizando os genótipos de adultos e progênies foram investigadas a herança Mendeliana, ligação genética e o desequilíbrio genotípico de nove locos de C. estrellensis, os quais exibiram herança Mendeliana, não estão ligados e segregam de forma independente. Embora a riqueza alélica ( ), heterozigozidade observada ( ) e esperada ( ) foram similares entre adultos ( = 8,3, = 0,648, = 0,686) e sementes ( = 7,8, = 0,640, = 0,682), estes índices foram significativamente menores nas sementes. O índice fixação médio ( ) não foi significativamente maior do que zero, sugerindo ausência de endogamia nos adultos e nas sementes. A taxa de cruzamento multilocos ( ) foi significativamente menor que a unidade (1,0), sugerindo autofecundações. A taxa de cruzamento entre indivíduos parentes ( ) foi significativamente maior do que zero (0,062) e a correlação de paternidade foi maior dentro ( = 0,835) do que entre frutos ( = 0,062). O coeficiente médio de coancestria ( ) foi maior e o tamanho efetivo ( ) foi menor do que o esperado para progênies de populações panmíticas. O número estimado de árvores matrizes para a coleta de sementes para obter um tamanho efetivo de 150 foi de 52. A taxa de imigração de pólen foi de 9,4%. O raio efetivo de dispersão de pólen ( ) foi de 974 m. A análise de modelagem de dispersão de pólen de Kernel indicou o modelo de dispersão exponencial como o que melhor explica a dispersão de pólen, com média de dispersão de pólen de 610,9 m. Portanto, a população de C. estrellensis não está reprodutivamente isolada devido à dispersão de pólen a longas distâncias e apresenta grande potencial para fins de conservação genética in situ e ex situ.
Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae), popularly known as jequitibá-branco, is a tropical tree species typical of advanced successional stages, characteristic of climax forests. Although it ecological importance, the species is threatened with extinction, mainly due to the intense exploitation and degradation of its natural environment. The objective of this study was to investigate the genetic diversity, intrapopulation spatial genetic structure (SGS), the mating system and contemporary gene flow of a population of C. estrellensis, located in a forest fragment (448.2 ha) in the city of Bataguassu (State of Mato Grosso do Sul, Brazil), using microsatellite markers. Were mapped, measured (height and diameter at breast height) and genotyped all 285 adult trees found in the area and collected seeds from 20 matrices trees, 32 seeds per tree for the hierarchical analyses within and among fruits. Using the genotypes of adults and progenies were investigated Mendelian inheritance, genetic linkage and genotypic disequilibrium of nine loci of C. estrellensis, which exhibited Mendelian inheritance, are not linkaged and segregate independently. Although the allelic richness ( R ), observed heterozygosity ( Ho ) and expected ( He ) were similar among adults ( R = 8.3, Ho = 0.648, He = 0.686) and seeds ( R = 7.8, Ho = 0.640, He = 0.682), these indexes were significantly lower in the seeds. The average fixation index ( F ) was not significantly greater than zero, suggesting absence of inbreeding in adults and seeds. The rate of multilocus outcrossing ( m t ) was significantly less than unit (1.0), suggesting selfing. The outcrossing rate between related individuals ( m s t  t ) was significantly greater than zero (0.062) and the paternity correlation was higher within ( p(w) r = 0.835) than that among fruits ( p(a) r = 0,062). The average coefficient of coancestry (  ) was higher and the effective size ( Ne ) lower than expected for progenies of panmitic populations. The estimated number of matrices trees to collect seeds to obtain the effective size of 150 was of 52. The immigration rate of pollen was 9.4%. The effective radius of pollen dispersal ( ep r ) was of 974 m. The analysis of Kernel pollen dispersion modeling indicated the exponential dispersion model as the best explanation for pollen dispersion, with a pollen dispersion average of 610.9 m. Therefore, the population of C. estrellensis is not reproductively isolated due to the dispersion of pollen over long distances and presents great potential for in situ and ex situ genetic conservation purposes.
FAPESP: 2014/02675-8

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30

Kubota, Thaisa Yuriko Kuboyama. "Study of flow and contemporary pollen dispersal, mating system, spatial distribution of genotypes and inbreeding depression in fragmented population Cariniana estrellensis (Raddi) Kuntze, using microsatellite loci /." Ilha Solteira, 2017. http://hdl.handle.net/11449/150019.

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Orientador: Alexandre Magno Sebbenn
Resumo: Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae), popularmente conhecida como jequitibá-branco, é uma espécie arbórea tropical típica de estágios sucessionais avançados, característica de florestas clímax. Apesar da sua importância ecológica, a espécie encontra-se ameaçada de extinção, principalmente devido à intensa exploração e degradação de seu ambiente natural. O objetivo deste trabalho foi investigar a diversidade genética, a estrutura genética espacial intrapopulacional (EGE), o sistema de cruzamento e o fluxo gênico contemporâneo de uma população de C. estrellensis, localizada em um fragmento florestal (448,2 ha) na cidade de Bataguassu (Estado do Mato Grosso do Sul, Brasil), utilizando marcadores microssatélites. Foram mapeadas, medidas (altura e diâmetro a altura do peito) e genotipadas todas as 285 árvores adultas encontradas na área e coletadas sementes de 20 árvores matrizes, 32 sementes por árvore para as análises de forma hierárquica dentro e entre frutos. Utilizando os genótipos de adultos e progênies foram investigadas a herança Mendeliana, ligação genética e o desequilíbrio genotípico de nove locos de C. estrellensis, os quais exibiram herança Mendeliana, não estão ligados e segregam de forma independente. Embora a riqueza alélica ( ), heterozigozidade observada ( ) e esperada ( ) foram similares entre adultos ( = 8,3, = 0,648, = 0,686) e sementes ( = 7,8, = 0,640, = 0,682), estes índices foram significativamente menores nas sementes. O índice fixaçã... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor

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31

Pereira, Lya Carolina da Silva Mariano. "Estudos genéticos de jatobá (Hymenaea courbaril L.) em área natural e restauração florestal com espécies nativas." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-21032018-130558/.

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O bioma Mata Atlântica tem sofrido com a fragmentação florestal e como forma de reestabelecer ambientes florestais são realizados plantios de restauração. Porém, por muito tempo houve preocupação somente com a composição florística das áreas e a diversidade genética foi negligenciada. Além disso, muitas áreas são implantadas a partir de sementes coletadas em áreas florestais geralmente pouco conservadas, pequenas e isoladas, o que pode comprometer a qualidade genética das mudas, produzindo indivíduos menos adaptados em decorrência da depressão endogâmica. Assim este trabalho teve como objetivo principal analisar o aspecto genético em áreas de restauração na região do Pontal do Paranapanema e área natural de referência, o Parque Estadual Morro do Diabo (PEMD), utilizando o jatobá (Hymenaea courbaril L.) como espécie modelo. No capítulo 1 com o objetivo de verificar a diversidade genética de H. courbaril em áreas de restauração florestal, foram selecionadas duas áreas de plantio com espécies nativas. Nestas áreas e no PEMD foram coletadas amostras foliares de indivíduos adultos que foram genotipadas para oito locos microssatélites. No PEMD ainda foram coletados frutos em 12 matrizes para caracterização do sistema reprodutivo. As três áreas estudadas apresentaram diversidade genética e níveis de endogamia similares. Nas três áreas de estudo foi identificada baixa estruturação genética espacial. Houve predomínio de fecundação cruzada para a produção de frutos na área natural, porém a taxa de cruzamentos entre indivíduos aparentados foi até dez vezes maior que a observada em outras populações da espécie. No capítulo 2 com o objetivo de verificar se há depressão endogâmica em progênies provenientes do PEMD foram selecionadas 320 sementes de 12 matrizes. Estas e seus frutos foram medidos. As plântulas a que deram origem também foram mensuradas, mensalmente, durante 15 meses. Todos os indivíduos foram genotipadas para oito locos microssatélites. A coancestria, foi estimada e os indivíduos separados em: não aparentados (tu), aparentados (tr) e autofecundação (s). Foi verificada diferença entre as métricas das plantas de acordo com o nível de coancestria entre indivíduos. Também foram estimados os valores de depressão endogâmica (ID). A quantidade de indivíduos irmãos de autofecundação foi muito pequena, sendo a maioria proveniente de cruzamento entre indivíduos não aparentados. A depressão endogâmica por autofecundação foi mais evidente no peso e tamanho dos frutos, e amena ou inexistente para os demais caracteres. Isto provavelmente por estas sementes terem sido coletadas em um fragmento grande e bem conservado e que ainda não sofre as consequências da depressão endogâmica. Assim, nosso trabalho mostrou que áreas de restauração florestal que seguiram as recomendações genéticas de implantação, apresentam diversidade genética suficiente para H. courbaril, podendo estas áreas serem fonte de coleta de sementes no futuro. E que os indivíduos provenientes de sementes do PEMD não apresentaram efeito de depressão endogâmica até 15 meses de desenvolvimento em viveiro.
The Brazilian Atlantic Forest was severely deforested and restoration initiatives are necessary to reestablish environments. However, for a long time there is only concern over floristic composition and the genetic diversity has been neglected. In addition, several restoration areas are planted from seeds collected in forest areas that are generally poorly preserved, small and isolated, which may compromise the genetic quality of the seedlings, producing less adapted individuals due to inbreeding depression. The aim of this work was to analyze the genetic aspects of Hymenaea courbaril L. in restoration areas in Pontal do Paranapanema region, and a natural reference forest, the Morro do Diabo State Park (PEMD), where seeds were also collected. In Chapter 1, to verify the genetic diversity of H. courbaril in areas of forest restoration, using eight microsatellites, two restoration areas were selected. In these areas and in the PEMD, leaf samples from adult individuals were collected. In the PEMD, fruits were collected in 12 seed trees for mating system characterization. The three areas presented similar genetic diversity and levels of inbreeding. Low spatial genetic structure was identified in the three studied areas. In the natural forest, fruits were mainly produced through outcrossings, but the rate of mating among relatives was up to ten times higher than the observed in other H. courbaril populations. In Chapter 2, to verify the inbreeding depression in the PEMD were selected 320 seeds from eight seed trees. The seeeds and their fruits were measured. The seedlings were also measured monthly, during 15 months. All seedlings were genotyped with eight microsatellite loci. From the pairwise coancestry the seedlings were separated into three categories: outcrossing among unrelated individuals (tu), outcrossing among related individuals (tr), and selfing (s). We verified differences among groups in the metrics of seedlings according to the level of coancestry among individuals. The values of inbreeding depression (ID) were also estimated. The number of selfed seedlings were very small, and the majority were from outcrossing among unrelated individuals. Inbreeding depression by selfing was more evident in weight and size fruit, and was insignificant or non-existent for other characters. This is probably because these seeds were collected in a large and preserved forest fragment, that does not suffer the consequences of inbreeding depression yet. Thus, our work showed that forest restoration areas that followed the genetic recommendations present enough genetic diversity for H. courbaril, and these areas may be a source of seeds for collection in the future. Besides that, seedlings from seed trees in PEMD did not present inbreeding depression effect up to 15 months of nursery development.

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Zancanaro, Paolo Orlando. "Deriva genética de caracteres quantitativos em milho." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-16062016-172533/.

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A obtenção de genótipos superiores no melhoramento de plantas depende da existência de variabilidade genética. A existência de coleções de germoplasma representativas e a utilização de um tamanho adequado de amostra são fundamentais para a preservação das frequências alélicas e genotípicas, diminuindo a perda de variabilidade genética e postergando o aparecimento dos efeitos da deriva genética. Assim, teve-se como objetivo avaliar os efeitos da deriva genética em caracteres quantitativos em subpopulações de milho. Este estudo foi realizado a partir das populações originais BR-105 e BR-106, das quais 10 subpopulações foram obtidas em cada um dos cinco ciclos sucessivos de amostragem com tamanho efetivo reduzido, totalizando 50 subpopulações para cada população original, as quais foram posteriormente autofecundadas, gerando um nível a mais de endogamia. Os tratamentos foram constituídos de 10 amostras da população original sem autofecundação, 10 amostras com autofecundação, 50 subpopulações obtidas da população original e 50 subpopulações autofecundadas, totalizando 120 tratamentos para cada população, avaliados separadamente. Utilizou-se o delineamento em blocos casualizados no esquema de parcelas subdivididas em faixas hierárquico, em quatro ambientes com duas repetições por ambiente. Os caracteres avaliados foram produção de grãos (PG), prolificidade (PROL), comprimento e diâmetro de espigas (CE e DE), número de fileiras por espiga (NFE), número de grãos por fileira (NGF), altura de planta e espiga (AP e AE), florescimento masculino e feminino (FM e FF) e número de ramificações do pendão (NRP). Foram estimados os efeitos da deriva genética entre as médias das subpopulações nos dois níveis de endogamia e os efeitos da depressão por endogamia nas subpopulações dentro dos ciclos. Posteriormente, realizaram-se análises de regressão linear para as subpopulações nos dois níveis de endogamia, separadamente, e em conjunto. Foi verificada uma grande variação nas médias das subpopulações ao longo dos ciclos, indicando que a deriva genética causou diferenciação entre as mesmas e que estas se diferenciaram das populações originais. Detectaram-se efeitos significativos da deriva genética nas populações não autofecundadas para todos os caracteres avaliados, em maior número para PG, já que este caráter é mais sensível à deriva genética por possuir maior grau de dominância que os demais. Houve diminuição no número de estimativas de deriva significativas para as populações autofecundadas, incluindo mudanças na magnitude e no sinal das mesmas em relação às populações não autofecundadas. Para as estimativas de depressão por endogamia, os caracteres PG, NGF, FM e FF apresentaram maior quantidade de estimativas significativas que os demais. Para a maioria dos caracteres, a regressão linear explicou a maior parte da variação encontrada com o aumento dos coeficientes de endogamia. As populações BR-105 e BR-106, por terem estruturas genéticas distintas, apresentaram performances diferentes quanto aos efeitos da deriva genética. Enfim, como a deriva genética interfere na integridade genética das populações, torna-se importante considerar seus efeitos na coleta e manutenção dos bancos de germoplasma e nas populações utilizadas no melhoramento genético de plantas.
Obtaining superior genotypes in plant breeding depends on the existence of genetic variability. The existence of representative germplasm collections and the use of appropriate sample size are essential for preserving allelic and genotypic frequencies, reducing loss of genetic variability and delaying genetic drift effects. This study aimed to evaluate the effects of genetic drift in quantitative traits in subpopulations of maize. The original populations used were BR-105 and BR-106, of which 10 subpopulations were obtained in each five successive sample cycles with reduced effective size, accounting 50 subpopulations for each original population that were subsequently selfed to generate an additional level of inbreeding. The treatments consisted in 10 samples of the original population, 10 samples of the selfed original population, 50 non selfed subpopulations obtained from the original population and 50 selfed subpopulations, accounting 120 treatments for each population evaluated separately. It was used the randomized block strip-plot design, in four environments with two replications. The traits assessed were grain yield (GY), prolificacy (PROL), ear length and ear diameter (EL and ED), number of rows per ear (NRE), kernel-row number (KRN), plant and ear height (PH and EH), days to anthesis and silking (DA and DS), and number of tassel branches (NTB). It was estimated the effects of genetic drift between subpopulations means at both inbreeding levels, and the effect of the inbreeding depression in subpopulations within cycles. It was also performed linear regression analysis for subpopulations at both levels of inbreeding separately and together. A large variation was observed in the subpopulations means over cycles, indicating that genetic drift caused differentiation between them, and that they differed from the original populations. The effects of genetic drift were significant for all traits in the non selfed subpopulations, especially for GY, which is more sensitive to genetic drift effects by having a greater degree of dominance than the other traits. There was a decrease in the number of significant genetic drift estimates for selfed populations, including changes in magnitude and signs, compared to the non selfed populations. GY, KRN, DA and DS had higher number of significant inbreeding depression estimates than the other traits. Linear regression analysis explained most of the variation found with increasing homozygosity. As BR-105 and BR-106 populations have distinct genetic structures, they showed different performances regarding the effects of genetic drift. Therefore, genetic drift interferes in the genetic integrity of populations and it is important to consider its effect on the collection and maintenance of germplasm banks and populations used in plant breeding.

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Garbuglio, Deoclécio Domingos. "Variabilidade genética em progênies S1 e depressão por endogamia em populações de milho (Zea mays L.)." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-07032008-154821/.

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Os objetivos do presente trabalho se dirigem ao estudo da variabilidade genética e da depressão por endogamia em sete populações de milho de ampla base genética, visando ao melhoramento de populações e obtenção de linhagens endogâmicas promissoras. Foram instalados onze experimentos em blocos casualizados em um local (Anhembi, SP), com diferentes conjuntos (N) de progênies S1 obtidos de sete populações (GO-D: dentado, GO-F: flint, GO-L: espiga longa, GO-G: espiga grossa; e compostos G3, G4 e GO-S). Foram estimadas a variância genética entre médias de progênies (2G), a variância fenotípica entre médias de progênies?^ (2F?^) e o coeficiente de herdabilidade (sentido amplo) para médias de progênies (2X). As estimativas de h 2Xhforam altas para peso de espigas (PE: 0,89 a 0,94), comprimento da espiga (CE: 0,77 a 0,88) e diâmtero da espiga (DE: 0,77 a 0,92); e menores para altura da planta (AP: 0,58 a 0,80) e altura da espiga (AE: 0,54 a 0,84), demonstrando alto potencial das populações para seleção recorrente com progênies S1. A variável PE nas populações base usadas como testemunha, mostrou valores variando de 11200 kg.ha-1 (GO-D) a 12800 kg.ha-1 (G3). As médias de progênies S1 entre populações variaram de 6070 kg.ha-1 (GO-F) a 7380 kg.ha-1 (G4); a depressão por endogamia nas progênies S1 variou de 37,5% (G4) a 48,0% (G3) em relação à população base. Os estudos sobre endogamia envolvendo as sete populações foram conduzidos com amostras da população original não endógama (S0) e das gerações S1 e S2 de autofecundação. Os experimentos foram conduzidos em Londrina (PR) e Piracicaba (SP) em blocos casualizados com parcelas subdivididas, com as populações representadas nas parcelas e as gerações de endogamia nas sub-parcelas. A estimação da depressão por endogamia foi obtida pelo modelo de regressão linear Y = µ0 + ?, sendo ? a depressão por endogamia para 100% de homozigose. A depressão esperada para 50% de homozigose é ?/2, cujo valor em percentagem variou de 25,4% a 41,4% em Piracicaba e de 23,1% a 39,3% em Londrina. Para os demais caracteres, os efeitos depressivos foram menores, geralmente <25% para AP e AE e <15% para DE e CE.
The objectives of the present work were directed for the study of genetic variability and inbreeding depression in seven maize populations of broad genetic base, as a guide for population improvement and development of promising inbred lines. The field evaluation was in eleven experiments (randomized complete blocks) in one location (Anhembi, SP) with different groups (N) of S1 progenies obtained of seven populations (GO-D: dent type, GO-F: flint type, GO-L: long ear, GO-G: thick ear; and composites G3, G4 e GO-S). Estimates were obtained for genetic variance (?^: progeny mean basis), phenotypic variance of progeny means (2G2F?^), and coefficient of heritability (broad sense) for progeny means (2Xh). Estimates of 2Xhwere high for ear weight (PE: 0.89 to 0.94), ear length (CE: 0.77 to 0.88) and ear diameter (DE: 0.77 to 0.92); and lower for plant height (AP: 0.58 to 0.80) and ear height (AE: 0.54 to 0.84), thus showing the high potential of the populations for recurrent selection based on S1 progenies. Ear yield (PE) in the base populations used as ckecks varied from 11200 kg.ha-1 (GO-D) to 12800 kg.ha-1 (G3). The means of S1 progenies varied from 6070 kg.ha-1 (GO-F) to 7380 kg.ha-1 (G4); the inbreeding depression in S1 progenies varied from 37.5% (G4) to 48.0% (G3) relative to the non-inbred population. For the studies on inbreeding in the seven populations samples of the original non-inbred populations (S0) and S1 and S2 generations of inbreeding were used. Filed experiments were carried out in Londrina (PR) and Piracicaba (SP) in randomized blocks with spli-plots, where populations were in the whole plots and inbreeding generations in the sub-plots. The estimates of inbreeding depression were obtained by the linear regression model Y = µ0 + ?, where ? is the iinbreeding depression for 100% homozygosity. The expected inbreeding depression for 50% homozygosity is ?/2, and the estimates in percentage varied from 25.4% to 41.4% in Piracicaba and from 23.1% to 39.3% in Londrina. For the other traits the inbreeding effects were lower, in general <25% for AP and AE and <15% for DE and CE.

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34

Riihimäki, M. A. (Mona-Anitta). "Flowering time and natural selection in Arabidopsis lyrata." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514277945.

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Abstract Arabidopsis lyrata is a close outcrossing relative of Arabidopsis thaliana, the model organism of plant physiology and molecular biology. I studied variation in flowering time and the factors shaping the variation within and between A. lyrata populations in different environments. The role of the two important proximate factors determining flowering time, day length and temperature, were studied in climate chambers. The southern A. lyrata populations were found to flower in high frequency and quicker than northern A. lyrata populations in all studied environments, but the reaction of northern populations on long day length was found to be stronger than that of southern populations. Differences in vernalization requirement between A. lyrata populations were found in outdoor common garden, but in the climate chambers the results of vernalization experiments were not consistent. Strength and direction of selection on flowering time and other life history traits were studied in alpine and lowland A. lyrata populations in Scandinavia. Differences in selection were found both between populations and between years. Grazing sheep caused high levels of damage in inflorescences in the alpine population. In the lowland population there was less herbivory, caused by insects and hares. The difference in selection on flowering traits in the two study populations might be partly caused by selective grazing. Completely outcrossing mating system in A. lyrata is due to well developed self-incompatibility system. However, biparental inbreeding is likely to exist in natural populations and it may lead to spatial structuring of genetic variation within populations. I studied the effects of biparental inbreeding on components of fitness in A. lyrata in three different environments. I found inbreeding depression after sib-mating to be substantial. Stressful environment reduced the overall performance of the plants, but had no effect on the magnitude of inbreeding depression. A literature survey indicates that the observed levels of inbreeding depression in self-incompatible A. lyrata were higher than those of self-compatible species. This suggests that self-compatible species have purged some of their genetic load. The genetic basis of flowering time variation in A. lyrata can be further studied by using A. thaliana molecular tools.

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Mousset, Mathilde. "Système de reproduction et adaptation à la toxicité du sol chez la Brassicacée pseudo-métallophyte Noccaea caerulescens." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT157/document.

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Je m’intéresse à l’écologie évolutive et en particulier à l’évolution des systèmes de reproduction, à l’adaptation et aux interactions de ces deux processus. En effet, les modèles théoriques ainsi qu’un certain nombre d’observations en populations naturelles soulignent que le système de reproduction devrait avoir un effet majeur sur les processus évolutifs et démographiques en populations naturelles. Lors de ma thèse, j’aborde ces thèmes sous divers angles à partir d’une Brassicacée tolérante et hyper-accumulatrice aux métaux lourds, Noccaea caerulescens, et à partir de modèles théoriques. Dans un premier temps, je m’intéresse à la variation du système de reproduction en populations naturelles. Comment s’organisent les flux de gènes entre populations ou sous-populations, et entre individus d’une même population ? Je me suis particulièrement intéressée à l’influence de la pollution des sols sur le taux d’autofécondation chez N. caerulescens, aux flux de gènes entre populations vivant dans les mines et populations vivant sur des sols non contaminés, et à la structure à l’intérieur des populations. Afin de mieux comprendre les facteurs influençant le système de reproduction, j’ai ensuite testé l’effet de la densité en plantes sur le taux d’autofécondations en populations naturelles. Dans un second temps, je teste les interactions existant entre adaptation à des milieux potentiellement très toxiques et système de reproduction. Plus spécifiquement, je teste si la dépression de consanguinité dépend du niveau de stress que subissent les populations, en interaction avec l’histoire des pressions de sélection qu’on subies les populations par le passé. Enfin, à l’aide de simulations, j’étudie comment la variation interannuelle du système de reproduction peut influencer la probabilité d’adaptation de populations faisant face à un changement environnemental
During my PhD, I focused on the evolution of mating system, adaptation and the mutual influences of both processes. I have been studying different aspects of this interaction using a hypertolerant, hyperaccumulator plant species, Noccaea caerulescens. This species grows on former mines and non-contaminated soils in Europe and in particularly in the Cévennes, and it is an excellent model to study the interaction of local adaptation in a heterogeneous environment and mating system. Firstly, I finely characterized N. caerulescens mating system in natural population, and see how metal pollution affects the variation of mating system in the Cévennes region. I showed that contrary to a couple of classical results (Antonovics 1968), in this system, metallicolous populations have lower self-fertilization rates than nonmetallicolous populations (article submitted). I then tested our best potential factor potentially explaining the variation of mating system in natural populations: plant density. In two different measures, with two different methods, density seems to have no or only a weak effect on self-fertilization rates in Noccaea caerulescens (article in prep). In a second project, I test the interaction between inbreeding depression, stress and the history of adaptation to a given environment using Noccaea caerulescens. Inbreeding depression is known to vary with environment and, sometimes, stress. Both experimental data (Long et al 2013) and theoretical models (Ronce et al 2009) stress the importance of the effect of the history of selection and adaptation in populations on the magnitude of inbreeding depression. Since we have populations of Noccaea caerulescens that are adapted to different levels of pollution, since different levels of pollution impose differential stress on the two ecotypes (strong polution is not good for nonmetallicolous plants) and since the species is self-compatible, this seems like an excellent system to test predictions on the interaction of inbreeding depression and mating system

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Burrows, Ben Robert. "Do Severe Genetic Bottlenecks Lead to Greater Reproductive Failure?" Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1344.

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It is generally accepted that populations which experience severe bottlenecks have a reduction in fitness. One of the most frequently reported fitness costs is increased hatching failure in bottlenecked populations of birds. The mechanism responsible for increased hatching failure is unknown. Research on other animals suggest that reduced population numbers cause unavoidable inbreeding that in turn leads to abnormalities in the gametes. In this thesis I examine some of the possible causes for increased hatching failure in severely bottlenecked populations of introduced birds in New Zealand. I look at three traits identified as a cause for infertility or hatching failure previously and determine whether there is a link with the size of a population s bottleneck. It is possible that reduced numbers of sperm reaching the site of fertilisation is a primary cause of hatching failure. I examined the perivitelline membrane of various species of introduced birds and counted the total number of sperm present to compare to how many would be expected in non-bottlenecked species. Although there was no relationship between the size of the bottleneck and the number of sperm present, all species had lower than expected sperm counts. In many species of mammals, a reduction in the quality of sperm is attributed to inbreeding depression bought about by genetic bottlenecks. I next compared the level of sperm abnormalities, variation in midpiece size sperm, and sperm motility with the size of the bottleneck each species passed through when introduced to New Zealand. There was no significant correlation between either the variation in midpiece size or sperm motility with bottleneck size. However, there was a trend for species that passed through more severe bottlenecks to have a slightly higher level of midpiece size and lower motility. Finally, I examined whether there was a link between abnormalities in the eggshell and the size of the respective bottleneck. There was no significant change in eggshell thickness or any change in the number of pores associated bottleneck size. However, there was a decreased number of round pores in severely bottlenecked species, although the consequences of this are unknown. My findings do not directly link a single cause for increased hatching failure in bottlenecked species of birds, but they do highlight the need for monitoring of reproductive traits in endangered species that have experienced a population bottleneck.

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LIMA, Ana Patrícia Souza de. "Estrutura genética de populações cultivadas do camarão marinho Litopenaeus vannamei em Pernambuco." Universidade Federal Rural de Pernambuco, 2007. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6210.

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Although Brazil has an an important position in the world shrimp farming industry scenario, information on the genetic basis of the most important species, the exotic Litopenaeus vannamei, still scarce. The Brazilian shrimp industry has been facing difficulties, such as US antidumping action against shrimp products, unfavorable currency exchange rate impacts and viruses outbreaks. Shrimp resistant to viral diseases, as well as with better growth rates are wanted in breeding programs for this species in Brazil. A Federal Normative Instruction, instituted in 1997, prohibited shrimp importation into Brazil as a sanitary precaution to prevent the spread of shrimp diseases, and since then, all shrimp broodstock rely on the domesticated stocks. This fact raises questions about the success of a breeding program on this species, because one can not know if the genetic variability is enough to guarantee selection response. The objective of this study was to genetically characterize the broodstock of two shrimp hatcheries and to monitor the genetic variability of one of them after three consecutive broodstock replacements in the state of Pernambuco, Northeast Brazil. Genetic characterization of the two hatcheries was carried out using 5 microsatellite loci and pleopods tissue samples taken from 100 shrimp (50 of each broodstock). For the monitoring 3 microsatellite loci were used in 150 shrimp samples (50 of each broodstock replacement). Our results showed that there is sufficient genetic variability in both hatcheries based on the alleles frequency, inbreeding coefficient, FIS (Larv. A = 0,380 e Larv. B = 0,250), and observed and expected heterozygosities ranging from Ho= 0,190 to 0,810 and He= 0,460 to 0,870,respectively. The monitoring results showed that in closed systems, broodstock replacement does not interfer in the genetic variability, based on the alleles frequency, observed and expected heterozygosities (Ho= 0,460 and He= 0,660 in first sample collection, Ho= 0,420 and He= 0,620 in the second sample collection and Ho= 0,600 and He= 0,660 in the third sample collection), inbreeding coefficient, FIS (0,37 for the 1st, 0,39 for the 2nd and 0,13 for the 3rd sample collection). Our results suggested that genetic variability is high, thus reflecting the history of the shrimp activity in Brazil, where broodstock from different origins were introduced in the country up to 1997.
Desde 1997 a introdução de novos reprodutores de Litopenaeus vannamei está proibida pelo o Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA), Portaria de nº. 119, o que levanta questões sobre a viabilidade de programas de melhoramento no Brasil, uma vez que não há mais renovação dos plantéis. O objetivo do presente trabalho foi caracterizar geneticamente duas larviculturas de Litopenaues vannamei e monitorar a variabilidade genética de uma das larviculturas, com reposição de matrizes, em três períodos sucessivos, ambas, localizadas no estado de Pernambuco, Nordeste do Brasil. A caracterização genética foi feita usando 5 loci de microssatélites e um total de 100 amostras teciduais de reprodutores, para o monitoramento foram utilizados 3 loci de microssatélites e um total de 150 amostras teciduais de reprodutores. Foi evidenciado que há variabilidade genética suficiente nas duas larviculturas, para subsidiar programas de melhoramento genético, baseado na freqüência dos alelos, nos coeficientes de endogamia FIS (Larv. A = 0,380 e Larv. B = 0,250) e heterozigosidades que variaram de Ho= 0,190 a 0,810 e He= 0,460 a 0,870, respectivamente. Os resultados do monitoramento mostraram que a reposição de matrizes no sistema de ciclo fechado não interferiu na variabilidade genética desta larvicultura, o que pode ser evidenciado através da freqüência dos alelos, nas heterozigosidades obtidas que foram de Ho= 0,460 e He= 0,660 na primeira coleta, de Ho= 0,420 e He= 0,620 na segunda coleta e de Ho= 0,600 e He= 0,660 na terceira coleta, e nos valores do coeficiente de endogamia FIS (0,37 para a primeira coleta, 0,39 para a segunda coleta e 0,13 para a terceira coleta) encontrados. Os resultados aqui relatados podem ser considerados bons, refletindo a história da atividade no Brasil que se destacou pela introdução de reprodutores de diversas origens.

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Oliveira, Aurilene Santos. "Variabilidade genética e potencial produtivo em três populações semiexóticas de milho (Zea mays L.)." Universidade Federal de Goiás, 2013. http://repositorio.bc.ufg.br/tede/handle/tede/6536.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
With the possibility of planting corn in two seasons (normal and late crops) the Brazil has increased the total corn production, but it is necessary to develop new hybrids and varieties aiming to increase productivity in both planting dates, to attend increasing demand for this commodity. The objectives of the present work were directed for the study the genetic variability, evaluate the yield potential and estimate inbreeding depression in three semiexotic populations of maize, for purposes of recurrent selection. The field evaluation was in two experiments: Jataí (GO) and Anhembi (SP). The first experiment was represented by half-sib families, which were evaluated in randomized complete blocks with three replications with plots of 4m (0.90 m spacing) with 20 plants. The second experiment included half-sib and S1 families in two replications with plots of 3m (0,90 m spacing) with 15 plants. The following primary characters were evaluated: AP - plant height (cm), AE - ear height (cm), DE – ear diameter (cm), EC - ear length (cm), NP - number of plants, NE – ear of number, PE - ear weight (g parcela-1 ), PG – total grain weight (g parcela-1 ), PE4 - four ear weight, PG4 - four ear grain weight , NR -tassel branch number, CP - tassel length (cm), AD - evaluation of foliar disease and ACE - evaluation of corn stunt complex. The semiexótic populations CRE had an excellent pattern of genetic variability and a good productive potential, presenting an average yield of 70% compared to checks. Within the three populations it was observed differences of families in relation to resistance to corn stunt, indicating that selection for this trait can fairly effective.
RESUMO: Com a possibilidade do plantio de milho em duas épocas (safra e safrinha) o Brasil tem elevado a produção total de milho, porém é necessário desenvolver novos híbridos e variedades visando o aumento da produtividade em ambas as épocas de plantio, para atender a crescente demanda pelo grão de milho. Os objetivos do presente trabalho se dirigem ao estudo da variabilidade genética, avaliar o potencial produtivo, estimar a depressão por endogamia e avaliar o comportamento quanto a resistência ao complexo de enfezamento em três populações semiexóticas de milho, para fins de seleção recorrente. Foram instalados dois experimentos: Jataí (GO) e Anhembi (SP). No primeiro experimento foram utilizadas famílias de meios-irmãos, que foram avaliadas em experimentos delineados em blocos casualizados com três repetições de parcelas de 4m (espaçamento de 0,90m) com 20 plantas. No segundo experimento foram utilizadas famílias de meios-irmãos e famílias S1 com duas repetições de parcelas de 3m (espaçamento de 0,90m) com 15 plantas. Foram avaliados os seguintes caracteres: AP – altura de planta (cm), AE – altura de espiga (cm), DE – diâmetro de espiga (cm), CE – comprimento de espiga (cm), NP – número de plantas, NE – número de espiga, PE – peso de espiga (g.parcela-1 ), PG – peso de grãos (g.parcela-1 ), PE4 – peso de quatro espiga, PG4 – peso de grãos de quatro espiga, NR – número de ramificações do pendão, CP – comprimento de pendão (cm), AD – avaliação de doença foliar e ACE – avaliação do complexo de enfezamento. As populações semiexóticas apresentaram um excelente padrão de variabilidade genética e um bom potencial produtivo, apresentando em média produtividade de 70% em relação à testemunha. Dentro das três populações observou-se um comportamento diferente das famílias em relação à resistência ao complexo de enfezamento, indicando que seleções para este caráter nas populações pode trazer resultados satisfatórios.

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McSweeny, Andrew. "Genome Evolution Model (GEM): Design and Application." University of Toledo Health Science Campus / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=mco1290550446.

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Doublet, Anna-Charlotte. "La diversité génétique à l’ère de la génomique : évolution de la consanguinité et ses conséquences dans trois races bovines laitières françaises." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASB016.

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La sélection génomique, mise en place depuis 2009 en France, a drastiquement modifié les schémas de sélection dans les races bovines laitières françaises de grand effectif en augmentant le nombre de candidats à la sélection et en réduisant les intervalles de génération. L’essor de l’utilisation du transfert embryonnaire a également remanié les schémas de sélection, intensifiant la sélection des mères à taureaux et réduisant encore les intervalles de génération. Ces technologies permettent une augmentation du progrès génétique.Cependant, si leur utilisation n’est pas maîtrisée, elles mettent en danger la diversité génétique de ces races. Cette perte de diversité, caractérisée par une augmentation de la consanguinité, peut s’accompagner de dépression de consanguinité, d’une baisse de l’efficacité de la sélection et une perte de potentiel adaptatif. Il est donc primordial de comprendre et de prédire l’impact de ces changements sur la diversité génétique à l’ère de la génomique, afin de mieux la maintenir.Un bilan de la mise en place de la sélection génomique a montré que cette technologie a permis une augmentation du progrès génétique annuel chez la Montbéliarde, la Normande et la Prim’Holstein mais que la perte de diversité génétique s’est accélérée seulement chez la Prim’Holstein.Une étude par simulations a montré que, dans le cadre de la sélection génomique, l’utilisation intensive du transfert embryonnaire dans un schéma de sélection de type Montbéliarde présentait un risque pour la diversité génétique, et que la réduction du nombre de taureaux dans ces schémas causait à la fois une baisse du progrès génétique et une accélération de la perte de diversité génétique.Dans la race Montbéliarde, la dépression de consanguinité a fait baisser les performances pour cinq caractères de production et de santé sur les six caractères étudiés. Les effets de la consanguinité sur ces performances sont très hétérogènes le long du génome.Gérer la consanguinité et ses conséquences dans les races bovines laitières françaises nécessite la mise en œuvre de mesures efficaces, éthiques et applicables sur le terrain
Genomic selection, implemented in France since 2009, has drastically modified breeding schemes in large French dairy cattle breeds by increasing the number of candidates for selection and reducing generation intervals. The growing use of embryo transfer has also reshaped breeding schemes, intensifying the selection of dams of bulls and further reducing generation intervals. This resulted in an increased genetic gain.However, if their use is not controlled, they put the genetic diversity of these breeds at risk. This loss of diversity, characterized by an increased inbreeding, can be accompanied by inbreeding depression, a decrease in selection efficiency and a loss of adaptive potential. It is therefore essential to understand and predict the impact of these changes on genetic diversity. We studied the implementation of genomic selection and showed that this technology has led to an increase in annual genetic gain in Montbéliarde, Normande and Prim'Holstein while the loss of genetic diversity has only been accelerated in Prim'Holstein.We showed by simulations that, in the context of genomic selection, the intensive use of embryo transfer in a Montbéliarde-type breeding scheme presented a risk for genetic diversity, and that the reduction in the number of bulls in these schemes caused both a decrease in genetic gain and an acceleration of the loss of genetic diversity.In the Montbéliarde breed, inbreeding depression resulted in lower performance for five production and health traits out of six traits studied. The effects of inbreeding on these performances were very heterogeneous along the genome.Managing inbreeding and its consequences in French dairy cattle breeds requires the implementation of effective, ethical and feasible actions in the field

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Godoy, Amanda Regina [UNESP]. "Depressão endogâmica em pepino caipira." Universidade Estadual Paulista (UNESP), 2004. http://hdl.handle.net/11449/93522.

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The objective of this work was evaluate the inbreeding depression with successive generations of self-pollination in a cucumber caipira population (S0, S1, S2, S3; S4 e S5), obtained by crossing Safira x Hatem hybrids. Two experiments were accomplished: one to evaluate immature fruits production and another to analyze the mature fruits production, seed quality and yield. The experimental design of both experiments were randomized blocks, in the first with seven treatments (different generations of self pollination - S0 to S5 and the hybrid Safira), six replicates and five plants per plot and in the second the same seven treatments, four replicates and five plants per plot. In the first experiment (immature fruits) was number of leaves, length of the main stem, number and weight of fruits, total and commercial, number of nodes and vines percentage were evaluated. In the second experiment (mature fruit) the following traits were evaluated characteristic: seed number and weight per plant and per fruit and seed quality (germination test, first counted of seeds, index of germination speed and weight of 100 seeds). The averages were compared by the Tukey test (5%) and the evaluation of the inbreeding depression was made with regression analysis. In the experiment 1 smaller production of fruits was observed (total and commercial) starting from population S2, demonstrating possible vigor loss. The populations S0 and S1 were similar or superiors for the characteristics number of total fruits, total weight per plant and commercial weight per plant when compared to the hybrid Safira, demonstrating the potencial of this population to obtain a new cultivar or hybrid of the caipira type. The experiment two there was no statistical difference for all the appraised characteristics, showing that the inbreeding didn`t affect the production and quality of the seeds in this population.

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42

Godoy, Amanda Regina 1978. "Depressão endogâmica em pepino caipira /." Botucatu, 2004. http://hdl.handle.net/11449/93522.

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Orientador: Antonio Ismael Inácio Cardoso
Banca: Noberto da Silva
Banca: Cyro Paulino da Costa
Abstract: The objective of this work was evaluate the inbreeding depression with successive generations of self-pollination in a cucumber "caipira" population (S0, S1, S2, S3; S4 e S5), obtained by crossing Safira x Hatem hybrids. Two experiments were accomplished: one to evaluate immature fruits production and another to analyze the mature fruits production, seed quality and yield. The experimental design of both experiments were randomized blocks, in the first with seven treatments (different generations of self pollination - S0 to S5 and the hybrid Safira), six replicates and five plants per plot and in the second the same seven treatments, four replicates and five plants per plot. In the first experiment (immature fruits) was number of leaves, length of the main stem, number and weight of fruits, total and commercial, number of nodes and vines percentage were evaluated. In the second experiment (mature fruit) the following traits were evaluated characteristic: seed number and weight per plant and per fruit and seed quality (germination test, first counted of seeds, index of germination speed and weight of 100 seeds). The averages were compared by the Tukey test (5%) and the evaluation of the inbreeding depression was made with regression analysis. In the experiment 1 smaller production of fruits was observed (total and commercial) starting from population S2, demonstrating possible vigor loss. The populations S0 and S1 were similar or superiors for the characteristics number of total fruits, total weight per plant and commercial weight per plant when compared to the hybrid Safira, demonstrating the potencial of this population to obtain a new cultivar or hybrid of the "caipira" type. The experiment two there was no statistical difference for all the appraised characteristics, showing that the inbreeding didn't affect the production and quality of the seeds in this population.
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43

Charrier, Olivia. "Histoire biogéographique et système de reproduction de Rhododendron ferrugineum dans les Pyrénées." Thesis, Toulouse, INSA, 2014. http://www.theses.fr/2014ISAT0034/document.

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Les changements globaux récents affectent la physiologie, la distribution et la phénologie des espèces, ainsi que la dynamique des populations et les interactions entre espèces. Les interactions plantes-pollinisateurs sont particulièrement menacées par les changements globaux et la perturbation de ces interactions peut avoir des conséquences importantes sur le système de reproduction des espèces végétales. Dans ce contexte des changements globaux, nous avons déterminé les cortèges de visiteurs de Rhododendron ferrugineum le long de gradients environnementaux et étudié comment la variabilité de leur efficacité affectait le système de reproduction de cette espèce. Nous nous sommes également intéressés à l’histoire biogéographique de cette espèce et comment elle a répondu à des changements passés tels que les dernières glaciations. Nous avons mis en évidence que R. ferrugineum est visité par une large diversité d’espèces d’insectes. L’efficacité des cortèges de visiteurs varie le long de gradients environnementaux mais ne semble pas avoir un impact sur le système de R. ferrugineum. Cette espèce présente un système mixte de reproduction, avec une capacité à l’autofécondation mais les taux élevés de dépression de consanguinité limitent le développement des individus issus d’autofécondation. Cette forte dépression de consanguinité a permis un maintien relativement élevé de la diversité génétique dans les Pyrénées. Un tel niveau de dépression de consanguinité ne permet pas l’évolution de l’autofécondation et maintient ainsi le système mixte de reproduction chez R. ferrugineum. La capacité d’autofécondation de R. ferrugineum pourrait lui permettre de coloniser de nouveaux milieux ou de survivre aux changements globaux. Durant les dernières glaciations, R. ferrugineum a survécu dans de grands refuges de basse altitude ainsi que dans des nunataks (refuges de haute altitude). Quelques populations marginales présentent un taux significatifs de consanguinité (FIS> 0) et des niveaux de diversité génétique particulièrement faibles. Ce patron génétique est consistant avec des évènements de fondation accompagnés de perte de diversité génétique et d’hétérozygotie durant les périodes d’expansion de l’aire de répartition de l’espèce. Ces données suggèrent que la dépression de consanguinité dans ces populations devait être faible et que l’assurance reproductive a joué un rôle fondamental dans l’établissement de ces populations
Recent global changes affect the physiology, distribution and phenology of species, also they impact population dynamic and interactions among species. Plantpollinators interactions are particularly threated by global changes and perturbations of these interactions may lead to important changes in plant mating system. In this context of globalchanges, we determined the pollinator assemblages of Rhododendron ferrugineum and howthe variability of their efficiencies affects the mating system. We also studied thebiogeographic history of R. ferrugineum and how it responds to past climatic changes.We have shown that R. ferrugineum is visited by a large variety of insects. Visitorassemblages efficiency varied along environmental gradients but did not seem to impact themating system of R. ferrugineum. This species presents a mixed mating system, indeed it isable to self-fecundate but high levels of inbreeding depression are limiting the development of self-fecundate descendants. High levels of inbreeding depression maintain high genetic diversity in the Pyrenees. Also, it did not allow the evolution of selfing and maintain a mixed mating system. The ability to self-fecundate may favor the colonization of new habitats.During the last glaciation, R. ferrugineum survived in large lowland refugia and in nunataks at high altitude. Some marginal populations present a high level of selfing (FIS> 0) and low genetic diversity. This genetic pattern is consistent with foundation events and loss of genetic diversity and heterozygosity along colonization rods. Our data suggest that inbreeding depression in these populations should have been low and the reproductive assurance played akey role in the establishment of these populations

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Chuine, Anna. "Des mécanismes aux conséquences adaptatives du choix du partenaire sexuel pour la compatibilité génétique : exemple d'un hyménoptère parasitoïde soumis à la dépression de consanguinité." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10079.

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L’haplodiploïdie chez les hyménoptères leur confère une meilleure résistance aux effets délétères de la dépression de consanguinité. Cependant, certains hyménoptères ont un déterminisme du sexe particulier qui les rend sensibles à cette dépression. Chez ces espèces, le genre des individus dépend de la complémentarité des allèles à un locus donné, le single-locus Complementary Sex Determination (sl-CSD). Les oeufs non fécondés se développent en mâles haploïdes alors hémizygotes au locus de CSD. En revanche les oeufs fécondés donnent des femelles diploïdes s’ils sont hétérozygotes au locus du CSD mais deviennent des mâles diploïdes s’ils sont homozygotes pour ce même locus. Ces derniers sont d’autant plus fréquents dans les populations consanguines où le taux d’homozygotes est élevé. Or, les mâles diploïdes sont dans la majorité des cas non viables ou stériles. La production de tels mâles est de ce fait coûteuse pour les femelles. La faible viabilité des mâles diploïdes s’apparente alors à de la dépression de consanguinité. Par des approches liées à l’écologie comportementale et à l’écologie chimique le projet de thèse se concentre sur l’étude des coûts individuels générés par la production de mâles diploïdes et à l’évolution des comportements sélectionnés en réponse à ces coûts. Dans un premier temps, je me suis intéressée à la fitness des mâles diploïdes et aux répercussions de leur production sur les femelles de la population. Dans un second temps, j’ai étudié les comportements permettant de réduire les coûts de la production des mâles diploïdes. Les individus apparentés représentent les partenaires sexuels où le risque de produire des fils diploïdes est le plus élevé. De ce fait, les comportements d’évitement de la consanguinité devraient être sélectionnés dans ces populations
Haplodiploidy in hymenopterans offers a great resistance to the deleterious effect of inbreeding depression. However, some hymenopterans have a specific sex determination which drives them to this depression. Among those species, the sex of individuals depends on allele complementary at a particular locus; the single-locus Complementary Sex Determinatation (sl-CSD). Unfertilized eggs give birth to haploid males which are hemizygotes at the CSD locus. Conversely, fertilized eggs develop into females when heterozygote at the CSD locus but become diploid males when homozygote at the same locus. Diploid males are especially frequent in inbred populations with a high inbreeding rate. Yet diploid males are generally unviable or sterile. Production of such males is therefore costly for females. Reduced viability of diploid males is then similar to inbreeding depression. Linked with behavioural ecology and chemical ecology approaches, the PhD project starts by focusing on individual costs due to production of diploid males, and then on behaviours that have evolved in response to these costs. As a first step, the fitness of diploid males and its impact on females of the population have been measured. If they are unviable, their production is akin to female mortality. As a second step, we studied behaviours that reduce the cost of diploid male production. Related individuals are sexual partners that are most likely to father diploid sons. Therefore, behavioural inbreeding avoidance may be selected in such populations

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45

Santacruz, Oviedo Victoria Rossmary [UNESP]. "Depressão endogâmica em uma população de pepino japonês (Cucumis sativus L.)." Universidade Estadual Paulista (UNESP), 2004. http://hdl.handle.net/11449/93561.

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Foram conduzidos dois experimentos na FCA/UNESP, objetivando avaliar a depressão causada por endogamia com sucessivas gerações de autofecundação em uma população de pepino do tipo japonês. No primeiro experimento foram avaliadas características de produção de frutos imaturos no período de 21/08/2002 à 29/11/2002 em ambiente protegido. No segundo experimento foram avaliadas características de produção e qualidade de sementes no período de 12/03/2003 à 13/06/2003 em condições de campo. A partir do intercruzamento entre plantas do híbrido Natsu suzumi foi obtida a geração F2, considerada como população S0. Obtiveram-se progênies S1, S2, S3, S4 e S5, através de autofecundações sucessivas pelo método do SSD ('Single Seed Descent'). Ao partir da mistura ao acaso de sementes de progênies com igual número de autofecundações sucessivas foram obtidas cinco populações denominadas de população S1 a população S5. Foram sete tratamentos (híbrido Natsu suzumi, populações S0 a S5) e o delineamento experimental foi em blocos ao acaso, com seis e quatro repetições no primeiro e segundo experimento, respectivamente e cinco plantas por parcela nos dois experimentos. No primeiro experimento (frutos imaturos) foram avaliados, número de folhas, comprimento da haste principal, número e massa de frutos, total e comercial, número de nós e porcentagem de brotações. No segundo experimento (frutos maduros) avaliaram-se características relacionadas com produção (número e massa de sementes por planta e por fruto) e qualidade de sementes (teste padrão de germinação, primeira contagem de sementes, índice de velocidade de germinação, massa de 100 sementes). Foram realizadas as análises de variância para cada característica, e as médias dos tratamentos foram comparadas pelo teste de Tukey (%). Também foram realizados análises de variância apenas com as seis...
Two experiments were set up at FCA/UNESP. The objective of this work was to evaluate the inbreeding depression with successive generations of self pollination in a cucumber Japanese population. It was studied one population F2 obtained from a commercial hybrid (Natsu suzumi) considered as S0 population. In the first experiment were appraised characteristics of production of immature fruits in the period of 21/08/2002 to 29/11/2002 in protected cultivation. In the second experiment were appraised seed production and quality in the period of 12/03/2003 to 13/06/2003 in open field conditions. It was obtained progenies S1, S2, S3, S4 and S5 through the 'Single Seed Descent' methodology. It was used randomized blocks with seven treatments (different generations of self pollination - S0 to S5 and the hybrid Natsu suzumi) six and four replicates in the first and second experiment and five plants per plot in both. In the first experiment (immature fruits) were evaluated number of leaves, length of the main stem, number and weight of fruits, total and commercial, number of nodes and vines percentage. In the second experiment (mature fruit) characteristic related with production were evaluated (number and weight of seeds per plant and per fruit) and quality of seeds (germination test, first counted of seeds, index of germination speed and weight of 100 seeds). The variance analyses were accomplished each characteristic and the averages of the treatments were compared by the test of Tukey (%). Also accomplished just with the six inbreed generations to evaluate the possible inbreeding depression (without including the commercial hybrid). In the comparison among the population differences were not observed for the characteristics appraised showing there were not production loss for inbreeding in this population. However, for the characteristics length of the main stem, number of total fruit, weight of seeds per fruit and seed number per fruit the commercial.

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46

Cristóbal, Helsi María Isidro. "Depressão endogâmica em características de crescimento e resistência a Piscirickettsia salmonis em salmão coho (Oncorhynchus kisutch) /." Jaboticabal, 2017. http://hdl.handle.net/11449/152017.

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Orientador: Roberto Carvalheiro
Coorientador: Lucia Galvão de Albuquerque
Banca: Carlos Antonio Lopes de Oliveira
Banca: Humberto Tonhati
Resumo: Os programas de melhoramento em espécies aquícolas apresentam, no geral, um número restrito de famílias e um pequeno tamanho efetivo populacional, levando ao acasalamento de animais aparentados e, consequentemente, ao aumento da endogamia. Por sua vez, maiores níveis de endogamia tendem a ocasionar queda no desempenho dos animais causada pela depressão endogâmica. O objetivo deste estudo foi estimar os níveis de endogamia e depressão endogâmica sobre as características de peso à despesca, comprimento à despesca e resistência a Piscirickettsia salmonis em uma população de salmão coho. A resistência a Piscirickettsia salmonis foi definida como o dia da morte de cada peixe após desafio conduzido em dois anos, com média de 42 dias em 2012 e 14 dias no ano de 2014. Foi utilizado um banco de dados composto por 53.504 observações, provenientes de nove gerações e 930 famílias. A estimação dos componentes de variância e endogamia foram obtidas utilizando o programa computacional AIREMLF90 e os valores de depressão endogâmica foram estimados a partir de um modelo animal. Os valores observados para o coeficiente de endogamia foram crescentes ao longo das gerações, com uma taxa média máxima de 8,75% no ano de 2014. A depressão endogâmica afetou em maior nível as características de peso à despesca e dia de morte, com redução de 6,4 e 9,2% no desempenho dos animais, respectivamente, para o nível máximo de endogamia observado (30%). Os resultados indicam a necessidade de uso de estratégias ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Aquaculture breeding programs present, in general, low number of families and reduced effective population size, resulting in mating of related animals and, consequently, increased level of inbreeding. High inbreeding coefficient may negatively impact the animals' performance due to inbreeding depression. The objective of this study was to estimate inbreeding coefficient and inbreeding depression on growth traits and resistance against Piscirickettsia salmonis in a coho salmon population. Resistance against P. salmonis was defined as days to death of each fish after being challenged in two different years, with an average of 42 days in 2012 and 14 days in 2014. Data of 53,504 animals from 930 families was analyzed. Variance components were estimated using the software AIREMLF90, and inbreeding depression was estimated under an animal model. An increasing rate of inbreeding was observed, attaining an average of 8.75% in 2014. Inbreeding depression was more pronounced for harvest weight (PD) and days to death (DM), in comparison with harvest length. At the highest observed inbreeding level (30%), the estimated reduction caused by inbreeding depression was equal to 6,4% for PD and 9,2% for DM. The results indicate the necessity to control inbreeding more effectively for the studied coho salmon population, to guarantee genetic progress in the long term.
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47

Santacruz, Oviedo Victoria Rossmary 1968. "Depressão endogâmica em uma população de pepino japonês (Cucumis sativus L.) /." Botucatu : [s.n.], 2004. http://hdl.handle.net/11449/93561.

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Orientador: Antonio Ismael Inácio Cardoso
Banca: Noberto da Silva
Banca: Keigo Minami
Resumo: Foram conduzidos dois experimentos na FCA/UNESP, objetivando avaliar a depressão causada por endogamia com sucessivas gerações de autofecundação em uma população de pepino do tipo japonês. No primeiro experimento foram avaliadas características de produção de frutos imaturos no período de 21/08/2002 à 29/11/2002 em ambiente protegido. No segundo experimento foram avaliadas características de produção e qualidade de sementes no período de 12/03/2003 à 13/06/2003 em condições de campo. A partir do intercruzamento entre plantas do híbrido Natsu suzumi foi obtida a geração F2, considerada como população S0. Obtiveram-se progênies S1, S2, S3, S4 e S5, através de autofecundações sucessivas pelo método do SSD ('Single Seed Descent'). Ao partir da mistura ao acaso de sementes de progênies com igual número de autofecundações sucessivas foram obtidas cinco populações denominadas de população S1 a população S5. Foram sete tratamentos (híbrido Natsu suzumi, populações S0 a S5) e o delineamento experimental foi em blocos ao acaso, com seis e quatro repetições no primeiro e segundo experimento, respectivamente e cinco plantas por parcela nos dois experimentos. No primeiro experimento (frutos imaturos) foram avaliados, número de folhas, comprimento da haste principal, número e massa de frutos, total e comercial, número de nós e porcentagem de brotações. No segundo experimento (frutos maduros) avaliaram-se características relacionadas com produção (número e massa de sementes por planta e por fruto) e qualidade de sementes (teste padrão de germinação, primeira contagem de sementes, índice de velocidade de germinação, massa de 100 sementes). Foram realizadas as análises de variância para cada característica, e as médias dos tratamentos foram comparadas pelo teste de Tukey (%). Também foram realizados análises de variância apenas com as seis... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Two experiments were set up at FCA/UNESP. The objective of this work was to evaluate the inbreeding depression with successive generations of self pollination in a cucumber Japanese population. It was studied one population F2 obtained from a commercial hybrid (Natsu suzumi) considered as S0 population. In the first experiment were appraised characteristics of production of immature fruits in the period of 21/08/2002 to 29/11/2002 in protected cultivation. In the second experiment were appraised seed production and quality in the period of 12/03/2003 to 13/06/2003 in open field conditions. It was obtained progenies S1, S2, S3, S4 and S5 through the 'Single Seed Descent' methodology. It was used randomized blocks with seven treatments (different generations of self pollination - S0 to S5 and the hybrid Natsu suzumi) six and four replicates in the first and second experiment and five plants per plot in both. In the first experiment (immature fruits) were evaluated number of leaves, length of the main stem, number and weight of fruits, total and commercial, number of nodes and vines percentage. In the second experiment (mature fruit) characteristic related with production were evaluated (number and weight of seeds per plant and per fruit) and quality of seeds (germination test, first counted of seeds, index of germination speed and weight of 100 seeds). The variance analyses were accomplished each characteristic and the averages of the treatments were compared by the test of Tukey (%). Also accomplished just with the six inbreed generations to evaluate the possible inbreeding depression (without including the commercial hybrid). In the comparison among the population differences were not observed for the characteristics appraised showing there were not production loss for inbreeding in this population. However, for the characteristics length of the main stem, number of total fruit, weight of seeds per fruit and seed number per fruit the commercial.
Mestre

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48

Annavi, Geetha. "Genetic, socio-ecological and fitness correlates of extra-group paternity in the European badger (Meles meles)." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:8d7304b2-84a2-4d5d-bbbc-63270d309e2e.

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The evolution of extra-group paternity (EGP) is a contentious issue in evolutionary biology. This thesis examines the factors and adaptive benefits driving EGP in a high-density, group-living population of European badgers (Meles meles). To improve power to assign parentage, I isolated and characterised 21 new polymorphic microsatellite markers. I genotyped 83% of 1410 badger trapped 1987‒2010 using 35 autosomal microsatellite markers. Maternity and paternity were assigned at 80% confidence ca. 82% of individuals. 48% of paternities were extra-group, where 85% were attributable to neighbouring-group males and EGP was detected in 47% of litters; thus badger social group do not correspond with a breeding unit. I tested whether indirect genetic benefits explain these high EGP rates. (1) ‘Good-gene-as-heterozygosity Hypothesis’: Paternal heterozygosity, but not maternal or an individual’s own heterozygosity, associated positively with first-year survival probability. Under benign environmental conditions, cubs fathered by more heterozygous males had a higher first year survival probability. Despite this correlation, the EGP rate per litter correlated with neither average nor maximum within-group heterozygosity of candidate fathers. (2) Fitness benefit Hypothesis: Extra-group offspring (EGO) had lower first-year survival probability and lived 1.3 years less than within-group offspring (WGO). Female WGO produced more litters and offspring over their lifetime than female EGO, whereas male EGO produced more offspring than male WGO. (3) Inbreeding avoidance hypothesis: The EGP rate within a litter increased with greater average pair-wise relatedness between mothers and within-group candidate fathers. No inbreeding depression on first-year survival probability was detected, but small sample sizes limited statistical power. Socio-ecologically, at the litter level, EGP correlated negatively with the number of within-group candidate fathers, and positively with neighbouring-group candidate fathers. In conclusion, EGP in badgers may reduce inbreeding and be maintained in the population through a sex-specific antagonistic selection and indirect genetic benefits may occur when the total fitness benefits of producing extra-group sons outweigh the costs of producing extra-group daughters. These indirect genetic benefits only partially explain the evolution of promiscuity in European badgers, highlighting that evolutionary factors underlying promiscuity remain unclear.

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Davila, Yvonne Caroline. "Pollination ecology of Trachymene incisa (Apiaceae): Understanding generalised plant-pollinator systems." Thesis, The University of Sydney, 2006. http://hdl.handle.net/2123/1896.

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A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.

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50

Davila, Yvonne Caroline. "Pollination ecology of Trachymene incisa (Apiaceae): Understanding generalised plant-pollinator systems." University of Sydney, 2006. http://hdl.handle.net/2123/1896.

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Abstract:

Doctor of Philosophy (PhD)
A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.

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