Dissertations / Theses on the topic 'Habitat differentiation'
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Ellegaard, Kirsten Maren. "Genome Evolution and Niche Differentiation of Bacterial Endosymbionts." Doctoral thesis, Uppsala universitet, Molekylär evolution, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-217724.
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Most animals contain chronic microbial infections that inflict no harm on their hosts. Recently, the gut microflora of humans and other animals have been characterized. However, little is known about the forces that shape the diversity of these bacterial communities. In this work, comparative genomics was used to investigate the evolutionary dynamics of host-adapted bacterial communities, using Wolbachia infecting arthropods and Lactobacteria infecting bees as the main model systems. Wolbachia are maternally inherited bacteria that cause reproductive disorders in arthropods, such as feminization, male killing and parthenogenesis. These bacteria are difficult to study because they cannot be cultivated outside their hosts. We have developed a novel protocol employing multiple displacement amplification to isolate and sequence their genomes. Taxonomically, Wolbachia is classified into different supergroups. We have sequenced the genomes of Wolbachia strain wHa and wNo that belong to supergroup A and B, respectively, and are present as a double-infection in the fruit-fly Drosophila simulans. Together with previously published genomes, a supergroup comparison of strains belonging to supergroups A and B indicated rampant homologous recombination between strains that belong to the same supergroup but were isolated from different hosts. In contrast, we observed little recombination between strains of different supergroups that infect the same host. Likewise, phylogenetically distinct members of Lactic acid bacteria co-exist in the gut of the honeybee, Apis mellifera, without transfer of genes between phylotypes. Nor did we find any evidence of co-diversification between symbionts and hosts, as inferred from a study of 13 genomes of Lactobacillus kunkeei isolated from diverse bee species and different geographic origins. Although Lactobacillus kunkeii is the most frequently isolated strain from the honey stomach, we hypothesize that the primary niche is the beebread where the bacteria are likely to contribute to the fermentation process. In the human gut, the microbial community has been shown to interact with the immune system, and likewise the microbial communities associated with insects are thought to affect the health of their host. Therefore, a better understanding of the role and evolution of endosymbiotic communities is important for developing strategies to control the health of their hosts.
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Bartoszek, Joseph E. "Genetic Differentiation in Ambystomatid Salamanders Across a Fragmented Landscape." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1259031878.
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Marrotte, Robby. "The influence of habitat and landscape structure on the genetic differentiation of the white-footed mouse (Peromyscus leucopus)." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119521.
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The white-footed mouse (Peromyscus leucopus) is a widespread habitat generalist species abundant over a large part of the North-American continent. In the past decade, due to climate and land use change, the range of this species has expanded northwards into Canada. The black-legged tick (Ixodes scapularis), is the vector of Lyme disease which also has tracked climate change over the last few decades. This may have been further promoted by the growing presence of P. leucopus, a favored host for the tick. Therefore, aspects of the landscape that affect the movement and distribution of the white-footed mouse, will also affect the expansion of the tick, and consequently the spread of Lyme disease. In this thesis, I first reviewed published results that relied on genetic and non- genetic biological data to investigate the influence of local habitat and landscape characteristics on the movement and dispersal patterns in the white footed-mouse. Next, I evaluated the relations between breeding habitat and landscape resistance against the genetic differentiation between 11 populations in Montérégie, Québec, Canada. I was able to simultaneously measure the effect of the habitat and the landscape on the genetic differentiation of these mouse populations by utilizing numerical optimization to fit a model to previously published genetic data. I used ecological distance computed from resistance surfaces with Circuitscape to infer the effect of the landscape. Concurrently, I estimated the habitat quality of our sampling localities and correlated these to relevant habitat measurements. I found that both characteristics within and between forest patches have more of an impact on genetic differentiation than the geographical distance between the mice populations. This suggests that this species can disperse and use a wide range of habitats, in accordance with its recent rapid expansion in the region.La souris à pattes blanches (Peromyscus leucopus) est une espèce généraliste à large distribution sur le continent Nord-américain. En relation avec le réchauffement climatique et les changements dans l'utilisation des terres, cette espèce étend sa distribution vers le nord au Canada. La tique à pattes noires (Ixodes scapulatis), vecteur de la maladie de Lyme, a aussi suivi le changement climatique par un déplacement de la limite nord de sa distribution au Canada. Cette expansion vers le nord pourrait avoir été favorisée par la présence croissante de P. leucopus, un hôte préférentiel pour la tique. Les aspects du paysage qui affectent le mouvement et la distribution de la souris à pattes blanches, affecteront ainsi l'expansion de la tique et par conséquent, de la maladie de Lyme. Dans ce mémoire, j'ai d'abord effectué une revue de publications qui ont examiné l'influence de caractéristiques d'habitat locales et du paysage sur le mouvement et la dispersion de la souris à pattes blanches. Ensuite, j'ai évalué l'influence de caractéristiques de l'habitat et du paysage sur la différenciation génétique entre des populations situées en Montérégie, Québec, Canada. J'ai pu mesurer simultanément l'effet de l'habitat et du paysage sur la différenciation génétique de 11 populations de souris en utilisant une optimisation numérique. J'ai utilisé des distances écologiques calculées à partir de surfaces de résistance avec Circuitscape pour déduire l'effet du paysage. En parallèle, j'ai estimé la qualité de l'habitat de sites d'échantillonnage et corrélé cet index aux mesures d'habitat prises sur le terrain. J'ai trouvé que les caractéristiques dans et entre les patches forestiers ont plus d'impact sur la différenciation génétique que la distance géographique. Ceci suggère que cette espèce peut disperser et utiliser une vaste gamme d'habitats, conformément à son expansion rapide récente dans la région.
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Hailu, Solomon Ghebremeskel. "THE EFFECT OF HABITAT FRAGMENTATION ON THE SPATIAL POPULATION GENETIC STRUCTURE OF SOUTHERN PINE BEETLE (DENDROCTONUS FRONTALIS)." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/624.
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Southern pine beetle (SPB), Dendroctonus frontalis (Zimmerman), is one of the most destructive insect pests of pine trees in southern United States, Mexico and Central America. There is relatively little information on the effect of habitat fragmentation on the connectivity and the spatial population genetics of SPB. This study therefore, adds to previously generated information by assessing how habitat fragmentation affects the spatial population genetic structure of SPB. It also introduces a new approach to the study of bark beetle population dynamics by assessing how landscape variables shape their effective dispersal. To address this issue, a suite of eight highly polymorphic DNA microsatellite markers were used to measure SPB movement over a representative range of SPB habitat and non-habitat (matrix). At the broadest scale, highly significant genetic differentiation suggests that the sampled populations are not panmictic. Loci with higher variability yielded higher resolution for both the infinite allele model based measure of differentiation (FST) and the stepwise mutation based measure (RST) estimates. It is apparent that allelic frequency differences, allelic size ranges and repeat motif played a role in the observed patterns of pair-wise differentiations between the sampled localities. It is supposed that gene flow, wide-range dispersal and recent divergent time could have contributed to the lower level of genetic structure observed in the pair wise estimates. The sampled populations did not show any differentiation attributable to the host species from which they were collected. Mantel test of genetic distance and Euclidean geographic distance revealed no correlation. Mantel tests of the correlation between genetic distance and cost weighted Euclidean distances also suggest that dispersal of SPB across geographic barriers is not significantly reduced. Thus, landscape features and host preference do not appear to have had an impact on population genetic structure of SPB. Since movements of these beetles were not significantly hindered by environmental factors like major rivers, roads, elevation and host type, it is advisable for regional pest management offices to put an effort and coordinate their prevention and management plans in a broader scale to alleviate the problem associated with this native insect pest. Disequilibrium in the observed homogenized pattern of the beetle in this study suggests human contribution in the dispersal of SPB. Therefore, stringent control is deemed necessary in transportation of logs. This could improve our pest management system hence its positive implication in timber industry is obvious.
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Schöttner, Sandra Iris [Verfasser]. "Bacterial habitat differentiation in cold- and warm-water coral reef ecosystems / Sandra Iris Schöttner. Max Planck Institute for Marine Microbiology." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2012. http://d-nb.info/1035019795/34.
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Streatfeild, Craig Anthony. "The effects of habitat fragmentation on the demography and population genetic structure of Uromys Caudimaculatus." Queensland University of Technology, 2009. http://eprints.qut.edu.au/26424/.
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Habitat fragmentation can have an impact on a wide variety of biological processes including abundance, life history strategies, mating system, inbreeding and genetic diversity levels of individual species. Although fragmented populations have received much attention, ecological and genetic responses of species to fragmentation have still not been fully resolved. The current study investigated the ecological factors that may influence the demographic and genetic structure of the giant white-tailed rat (Uromys caudimaculatus) within fragmented tropical rainforests. It is the first study to examine relationships between food resources, vegetation attributes and Uromys demography in a quantitative manner. Giant white-tailed rat densities were strongly correlated with specific suites of food resources rather than forest structure or other factors linked to fragmentation (i.e. fragment size). Several demographic parameters including the density of resident adults and juvenile recruitment showed similar patterns. Although data were limited, high quality food resources appear to initiate breeding in female Uromys. Where data were sufficient, influx of juveniles was significantly related to the density of high quality food resources that had fallen in the previous three months. Thus, availability of high quality food resources appear to be more important than either vegetation structure or fragment size in influencing giant white-tailed rat demography. These results support the suggestion that a species’ response to fragmentation can be related to their specific habitat requirements and can vary in response to local ecological conditions. In contrast to demographic data, genetic data revealed a significant negative effect of habitat fragmentation on genetic diversity and effective population size in U. caudimaculatus. All three fragments showed lower levels of allelic richness, number of private alleles and expected heterozygosity compared with the unfragmented continuous rainforest site. Populations at all sites were significantly differentiated, suggesting restricted among population gene flow. The combined effects of reduced genetic diversity, lower effective population size and restricted gene flow suggest that long-term viability of small fragmented populations may be at risk, unless effective management is employed in the future. A diverse range of genetic reproductive behaviours and sex-biased dispersal patterns were evident within U. caudimaculatus populations. Genetic paternity analyses revealed that the major mating system in U. caudimaculatus appeared to be polygyny at sites P1, P3 and C1. Evidence of genetic monogamy, however, was also found in the three fragmented sites, and was the dominant mating system in the remaining low density, small fragment (P2). High variability in reproductive skew and reproductive success was also found but was less pronounced when only resident Uromys were considered. Male body condition predicted which males sired offspring, however, neither body condition nor heterozygosity levels were accurate predictors of the number of offspring assigned to individual males or females. Genetic spatial autocorrelation analyses provided evidence for increased philopatry among females at site P1, but increased philopatry among males at site P3. This suggests that male-biased dispersal occurs at site P1 and female-biased dispersal at site P3, implying that in addition to mating systems, Uromys may also be able to adjust their dispersal behaviour to suit local ecological conditions. This study highlights the importance of examining the mechanisms that underlie population-level responses to habitat fragmentation using a combined ecological and genetic approach. The ecological data suggested that habitat quality (i.e. high quality food resources) rather than habitat quantity (i.e. fragment size) was relatively more important in influencing giant white-tailed rat demographics, at least for the populations studied here . Conversely, genetic data showed strong evidence that Uromys populations were affected adversely by habitat fragmentation and that management of isolated populations may be required for long-term viability of populations within isolated rainforest fragments.
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Deary, Alison L. "Ontogeny of the feeding apparatus and sensory modalities: Relationship to habitat differentiation among early life history stage drums (Sciaenidae) in the Chesapeake Bay." W&M ScholarWorks, 2015. https://scholarworks.wm.edu/etd/1539616627.
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Although the form and function of the structure of the feeding apparatus and diet are linked in adult fishes, it is often not clear when during ontogeny the ecomorphological patterns enable early life history stage fishes (ELHS) to partition their foraging niches and reduce competition. Sciaenid (family Sciaenidae) species exhibit variability in the structure of the feeding apparatus, which allows them to exploit more foraging habitats as adults than any other family in the Chesapeake Bay. In this study, ELHS and juvenile sciaenids representing three foraging guilds (pelagic: n=92, 2.9-48.2 mm SL; generalist: n=71, 4.3-53.8 mm SL; and benthic: n=75, 1.9-43.2 mm SL) were captured during weekly, shore-based ichthyoplankton and trawl surveys throughout the lower Chesapeake Bay, York River, and tidal inlets on Eastern Shore of Virginia. Stomachs were removed, specimens were cleared and double stained, and elements of the feeding apparatus were measured. A smaller subset of specimens (n=17) were stained using a 1% phosphotungstic acid solution and then scanned using micro-computed tomography to determine sensory modality in ELHS sciaenids representing the same foraging guilds. A dietary shift occurred first in pelagic sciaenids (16 mm SL), which corresponded to an expansion of sensory modalities, particularly gustation and audition that augment vision. The dietary shift was observed next in benthic sciaenids at 20 mm SL, which corresponded to the acquisition of oral and pharyngeal specializations suited to exploiting benthic prey even though they lacked sensory specializations. Finally, generalist sciaenids experienced a dietary shift at 35 mm SL, which occurred after the expansion of sensory modality (particularly vision, olfaction, gustation, and mechanoreception) but before specializations to the feeding apparatus were observed. Phylogenetic signal, measured as Pagel's lambda, was also calculated for oral jaw elements using a molecular and a morphological topology to determine if evolutionary history may constrain the configuration of these elements and to understand how topology may influence the detected phylogenetic signal. Pagel's lambda was low for pelagic sciaenids in premaxilla, lower jaw, and ascending process length, regardless of the topology used in the analysis. The signal was variable for benthic sciaenids depending on the topology used in the analysis; the signal was low when a morphological topology was used but was high for lower jaw and ascending process length when a molecular topology was used. In benthic sciaenids, Pagel's lambda, was intermediate for premaxilla length when the molecular topology was used, suggesting that the length of the premaxilla is influenced by natural selection despite some phylogenetic constraints. Therefore, the morphological patterns detected in ELHS sciaenids are not constrained exclusively by evolutionary history and represent ecomorphological, which suggest that sciaenids are able to partition foraging in nursery habitats during these early stages.
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Esperandio, Isadora Beraldi. "Rodovias atuam como barreira para o fluxo gênico de roedores subterrâneos? : o caso de Ctenomys minutus (Ctenomyidae)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/104747.
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Rodovias podem fragmentar populações por dois mecanismos, mortalidade e evitamento. Como espécies que evitam rodovias são raramente atropeladas por veículos e, então, não são detectadas em monitoramentos de fauna atropelada, outras abordagens são necessárias para identificar se eles estão sendo afetados. Ctenomys minutus (tuco-tuco) é um roedor subterrâneo que habita campos arenosos nas margens de rodovias e são raramente registrados em monitoramentos de fauna atropelada. Buscamos identificar se as rodovias são uma barreira para o fluxo gênico de tuco-tuco baseado em nove loci de microssatélite. Coletamos amostras de tecido epitelial de indivíduos de quatro populações: duas com a presença (Weber e Amaral) e, como controle, duas com a ausência de rodovia (Maribo I e Maribo II). Mensuramos diversidade genética, diferenciação genética (estatística F) e acessamos estrutura genética (agrupamento bayesiano). Não observamos redução na variabilidade genética e encontramos um baixo nível de isolamento entre Weber e Amaral e um isolamento ainda menor entre Maribo I e Maribo II. O método bayesiano separou os indivíduos em dois grupos, onde Maribo I e Maribo II são um grupo consistente e Weber e Amaral possuem fracas diferenciações. Os resultados nos indicam que um efeito de barreira entre as populações separadas pela rodovia está em processo e que é necessário mais tempo para observarmos de forma mais clara o isolamento. São necessários mais estudos genéticos e comportamentais para certificar este padrão. Sob aspectos práticos, seria adequado monitorar as populações afetadas e, eventualmente, aplicar alguma medida de mitigação na estrada pra proporcionar conectividade. Por fim, a abordagem genética se mostrou muito interessante para avaliar este impacto.Roads can fragment populations by two mechanisms, mortality and avoidance behavior. Since species that avoid roads are rarely killed by vehicles and thus cannot be detected in roadkill surveys, other approaches are necessary to identify whether they are affected. Ctenomys minutus (tuco-tuco) is a subterranean rodent who inhabits sand fields including at the margins of roads, however is rarely recorded on roadkill surveys. We aimed to identify if roads are a barrier to the gene flow of tuco-tuco based on nine microsatellite loci. We collected tissue samples from individuals of four populations: a pair with the presence (Weber and Amaral) and, as control, a pair with absence of a road (Maribo I and Maribo II). We measured the genetic diversity, the genetic differentiation (F-statistics), and assessed the genetic structure (Bayesian clustering). We observed no reduction in genetic variability and a low isolation level in pairwise comparison of Weber and Amaral, which was even lower between Maribo I and Maribo II. The Bayesian method separated individuals into 2 clusters, where Maribo I and Maribo II are one consistent cluster and Weber and Amaral present weak differentiations. The results indicate that a barrier effect between populations separated by roads is in process. More genetic and behavioral studies are needed to confirm this pattern. Under practical aspects, it would be appropriate to monitor the affected populations and possibly apply some mitigation measure on the road to provide connectivity. Finally, genetic approach proved very interesting to evaluate this impact.
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Bellamy, Stephen, and steve bellamy@flinders edu au. "RESOURCE PARTITIONING BETWEEN TWO SYMPATRIC AUSTRALIAN SKINKS, EGERNIA MULTISCUTATA AND EGERNIA WHITII STEPHEN BELLAMY Thesis submitted in total fulfilment of the requirements of the degree of Doctor of Philosophy AUGUST 2006 SCHOOL OF BIOLOGICAL SCIENCES FLINDERS UNIVERSITY, ADELAIDE, SOUTH AUSTRALIA ________________________________________." Flinders University. Biological Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20070124.145924.
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When species compete for resources, in a stable homogeneous environment, there are two possible outcomes. The first is that one species will out-compete the other and exclude it from the environment. This is known as the competitive exclusion principle. The second is that both species will manage to coexist. Coexistence can only occur if the species niches are differentiated such that interspecific competition is minimised, or eliminated. This outcome is known as resource partitioning.
Two closely related Australian skink species of the Egernia genus, Egernia multiscutata and Egernia whitii, are abundant and sympatric on Wedge Island in South Australias Spencer Gulf. The species are morphologically very similar and appear to have very similar life histories and habitat requirements. Ostensibly, they would compete for limiting resources in this environment.
This thesis is the first investigation into resource partitioning in this previously unstudied model organism. I report the results of multi-faceted investigations into the coexistence of the skinks, E. multiscutata and E. whitii on Wedge Island and the evidence for, and mechanisms of, any facultative resource partitioning between them.
Study methods involved a transect survey of most of Wedge Island to determine the species distributions and any evidence for resource partitioning; a morphological comparison to investigate any potential competitive advantages of either species; a habitat choice experiment to establish retreat-site preferences in the absence of interspecific interference; and, a series of staged dyadic encounter experiments to investigate interspecific competitive interactions.
Resource partitioning was evidenced by differential distributions of the species among substrates containing the elements required for permanent refuge shelters. This partitioning was not mediated by avoidance of particular substrates but by the presence of the opponent species, combined with attraction to suitable substrates. Asymmetries in some morphological characters were found to confer a potential competitive advantage to E. multiscutata in agonistic encounters with E. whitii. Both species were found to have the same refuge site preferences when interference competition was experimentally removed. This result was not concordant with observed resource partitioning in the field and suggests that the habitat choices of both species are modified by the presence of the opponent species. Analyses of staged dyadic encounter experiments showed that E. multiscutata was more likely to gain greater access to a contested habitat resource and more likely to exclude E. whitii from the resource than vice-versa. Nevertheless, the outcome of competitive interactions was not completely deterministic and there was some tolerance of co-habitation. E. multiscutatas competitive advantage was attributable largely to its greater mass and head dimensions relative to snout to vent length. However, differential behavioural responses to the threat of larger opponent size also played an important part in resource partitioning between the species.
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Aitken, Nicole. "Differentiating Habits for Pro-Environmental Behaviours." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32104.
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To help protect the environment people need to change current non-environmental behaviours into more sustainable behaviours. By understanding habits for pro-environmental behaviours, people can strive toward building a more sustainable future. The goal of this thesis was to identify different types of repeated pro-environmental behaviours and how to best foster strong habits for pro-environmental behaviours. To achieve this purpose we combined the theoretical framework of habits (Bargh, 1994; Verplanken, 2006) with the theoretical framework of self-determination theory (SDT; Deci & Ryan, 1985; 2000) to address current gaps in the habit literature.
The present thesis is comprised of two articles. The first article determined if the proposed indicators of habits (i.e., behaviour frequency, habit strength, and behaviour interference) could identify different patterns of repeated pro-environmental behaviours predicted by habit and self-determination theory using cluster analysis. The three studies provided support for the three proposed types of repeated behaviours: weak habits, repeated behaviours with interference, and strong habits. These results were very robust since the same pattern was found across three studies, three samples, and three different target behaviours.
The second article used the groups (i.e., weak habit, repeated behaviour with interference, and strong habit) in exploratory multinomial logistic regression analyses to identify factors related to pro-environmental behaviours which distinguished between the different types of repeated behaviours. Once again, the same three types of repeated behaviours were found across these three studies, with three new samples and two different target behaviours. Three predictors fairly consistently identified differences between the groups: autonomous motivation toward the environment, perceived importance of the environment, and the frequency of other pro-environmental behaviours. The implications of the thesis findings are discussed in relation to self-determination theory and the study of habits.
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Brengdahl, Martin. "Differentiation of dispersive traits under a fluctuating range distribution in Asellus aquaticus." Thesis, Linköpings universitet, Biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-108119.
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Knowledge about dispersion is of utmost importance for understanding populations’ reaction to changes in the environment. Expansion of a population range brings with it both spatial sorting and over time, spatial selection. This means that dispersion rates increases over time at the expanding edge. Most studies have so far been performed on continuously expanding populations. This study aims to bring more knowledge about dispersal biology in dynamic systems. I studied dispersal traits in two permanent and two seasonal vegetation habitats of an isopod (Asellus aquaticus), for which differentiation between habitat types has previously been shown. I quantified differences in displacement (dispersal rate) and three morphological traits, head angle (body streamline) and leg of the third and seventh pair of legs. Isopods from the seasonal vegetation had higher displacement rates than animals from permanent vegetation. This inclines that mechanisms driving spatial selection in expanding population ranges also exist in dynamic systems. The more streamlined isopods found in seasonal sites further points towards spatial sorting by dispersion capability. Because no effect of permanence was found on leg length and there was no correlation between streamlining and displacement, the higher dispersion among animals from seasonal habitats most likely derives from behavioral differences.
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Bova, Jacob Edward. "Morphological differentiation of eggs and comparative efficacy of oviposition and gravid traps for Aedes vectors at different habitats." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/64360.
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Mosquito surveillance is an integral part of understanding mosquito-borne disease, including and not limited to the La Crosse virus. The primary container-inhabiting Aedeni vectors include Aedes triseritatus, Aedes albopictus, and Aedes japonicus. To better understand the efficacy of gravid traps and oviposition traps as surveillance methods for these mosquitoes, field studies were conducted in three different habitat types.
Ae. triseriatus, Ae. albopictus, Ae. japonicus, and Aedes aegypti eggs were described with the aid of color images and SEM. All eggs were broadly cigar shaped with Ae. triseriatus and Ae. japonicus eggs being dull or matte black while Ae. albopictus and Ae. aegypti eggs were shiny jet black. Ae. triseriatus eggs were larger, lighter in color, and have a rougher appearance when compared to Ae. japonicus. Ae. albopictus and Ae. aegypti can be differentiated by the distinct presence of a micropylar collars in Ae. aegypti.
Ovitrap and gravid trap efficacy for the surveillance of Ae. triseriatus, Ae. albopictus, and Ae. japonicus were measured in three different habitats on two different sites. Both sites contained the same 2ha habitats with varying degrees of forest canopy disturbance. Ae. triseriatus was the most abundant mosquito on all sites. Ovitraps and gravid traps were efficient in collecting Ae. triseriatus, while ovitraps were not efficient in collecting Ae. japonicus and Ae. albopictus.Master of Science in Life Sciences
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Hagood, Susan. "Genetic differentiation of selected Eastern box turtle (Terrapene carolina) populations in fragmented habitats, and a comparison of road-based mortality rates to population size." College Park, Md. : University of Maryland, 2009. http://hdl.handle.net/1903/9995.
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Thesis (Ph.D.) -- University of Maryland, College Park, 2009.Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Mckeever, Samia. "Differentiating Geo-Spatiotemporal Aquatic Larval Habitats of Anopheles gambiae complex in Urban Agriculture and Urban Non-Agriculture Environments in Accra, Ghana." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5423.
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To meet the rising food demands of communities in Accra,Ghana, urban agriculture has been popularized as a way to increase food security and improve nutrition (Donovan et al., 2012). Urban agriculture is defined as "the cultivation of crops at both the subsistence and commercial levels including the keeping of livestock in open spaces in urban areas (Adjaye, n.d.). In Accra, urban agriculture covers 1,091 hectares, employs over one thousand people, and supplies residents with 90% of its vegetables ("Accra Metropolitan", n.d.). Further, 60% of households in Accra participate in backyard farming ("Accra Metropolitan", n.d.). Although urban agriculture provides many benefits for communities in Accra, it has been linked to the creation of suitable habitats for Anopheles gambiae complex larvae.
In Accra, a spatio-temporal distribution of An. gambiae complex larvae and larvae habitats has not been established. A larval study in two urban agriculture and two non-urban agriculture sites was conducted in the months of May, July, August, and September 2014. When combined together, 3,807 An. gambiae complex larvae were collected from the urban agriculture sites of Korle Bu and Opeibea over the period of the study. When combining the urban non-agriculture sites of Madina and Ashaiman, 2,484 An. gambiae complex larvae were collected over the same period. The results of this study in Accra show that Korle Bu, an urban agriculture site, was the most productive site, with 2,604 An. gambiae complex larvae collected for the months of May, July, August, and September. July was the most productive month for Korle Bu, with 1,653 An. gambiae complex larvae collected. Further investigations of An. gambiae complex larval habitats are necessary to better understand malaria transmission attributes unique to Accra, Ghana.
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Dennis, Barbara. "Scalogram analysis as a measure of dietary differentiation in relation to selected sociodemographic and health indicators among four ethnic groups residing in Jerusalem, Israel." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53868.
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A study was conducted to explore the usefulness of scalogram analysis of 24-hour recall dietary data as a measure of dietary complexity in relationship to other measures of social stratification, status incongruity and selected stress related health indicators in a population of Jerusalem adolescents and a sub-sample of their parents.
Data used in the study were collected as part of the Jerusalem Lipid Research Clinics Prevalence Study. The study sample consisted of 2,160 adults and seventeen year olds. Twenty four hour dietary recall data were transformed into a series of food group variables based on use of any, or non use of all, food item(s) in the group. Using a Guttman scale procedure with adjustment for misclassification, separate quasi scales were generated for each of the four major ethnic groups in the study sample. Ethnicity was determined by the country of birth for adults and country of father's birth for adolescents. Each scale contained five food groups.
Guttman scale scores and a dichotomous complexity score based on the Guttman scale scores were then compared with selected social stratification, nutritional, behavioral and health status variables. Univariate analyses of scale ranks with other variables showed a significant negative association with age and positive association with education of father. Spouse status inconsistency was marginally positively associated with dietary complexity. Spouse scale scores were significantly correlated for homogeneous (same origin) pairs but not for nonhomogeneous pairs. Fathers' complexity scores were associated with those of their children but mothers' scores were not. Nutrients associated with complexity were primarily fat, cholesterol and energy (positive), starch and carbohydrate (negative). Mean plasma cholesterol was higher in fathers in the high complexity group, compared to fathers in the low complexity group, but stress related health and behavioral variables did not appear to be related to dietary complexity as measured in this study. It was concluded that the Guttman procedure used with twenty-four hour recall data tends to scale one day dietary patterns rather than a dietary habit and only to the extent that the twenty-four hour intake represents habitual intake could it reliably scale people.Ph. D.
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Zoungrana, Paul Edith. "Mécanismes et enjeux de la différenciation sociale des immigrés burkinabe dans la construction d’une citoyenneté en côte d’ivoire. : Cas des habitants du village de Koudougou." Thesis, Perpignan, 2016. http://www.theses.fr/2016PERP0001.
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Ce travail de recherche s’inscrit dans une étude portant sur l’histoire des migrations en Afrique de l’ouest. De l’axe Burkina Faso /Côte d’ivoire et plus particulièrement des mécanismes d’intégration et de construction de la citoyenneté des immigrés vivant en zone rurale ivoirienne. La Côte d’Ivoire, terre historique de migrations diverses, jouissant d’une stabilité politique et socio-économique remarquablement apprécié, dans toute la sous région Ouest Africaine, a connue ces dernières années une succession de crises sociopolitique, qui a créer une fracture entre ses habitants vivant jadis en harmonie. Cette situation est liée pour beaucoup à la différenciation sociale et à l’exclusion d’une partie de sa population d’origine étrangère. Cette population d’étude, caractérisée par les immigrés burkinabés du village de Koudougou dans le centre ouest de la Côte d’Ivoire, nous orienteras dans notre recherche à travers la compréhension de leur trajectoire de migration, la différenciation sociale dont ils sont victimes dans leur lieu de sédentarisation et les mécanismes qu’ils mettent en place pour construire leur citoyenneté, en contournant les restrictions mis en place par la communauté d’accueilThis research is part of a study of the history of migration in West Africa. The axis Burkina Faso / Ivory Coast and especially the mechanisms of integration and building the citizenship of immigrants in Ivorian rural areas. Ivory Coast, historic land of various migrations, enjoying political stability and socio-economic remarkably popular, throughout the West African sub-region has experienced in recent years a succession of socio-political crises, which create a divide between its people once living in harmony. This situation is linked to many social differentiation and exclusion of part of its foreign population. This study population, characterized by the Burkinabe immigrants from the village of Koudougou in west central of Ivory Coast, will direct us in our search through the understanding of their migration path, social differentiation against them in their place of settlement and the mechanisms they put in place to build their citizenship, bypassing the restrictions put in place by the host community
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Pedersen, Alexander. "Ett sexuellt sökfält : En kvalitativ studie om socialt och sexuellt kontaktskapande på Grindr." Thesis, Linnéuniversitetet, Institutionen för samhällsstudier (SS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-107216.
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This study aims to understand how social and sexual relations are initiated, negotiated and constructed among homo- and bisexual men within a specific sexual field; the geo-social application Grindr. It’s based on qualitative and semi-structured interviews with six self-identified homosexual men in Sweden from various age groups and with various social backgrounds who are using, or has used, Grindr in order to initiate and establish contacts with other homo- and bisexual men. Of certain interest are their experiences of using the application and being a part of its social and sexual setting. In order to analyse the interviews, a combination of sexual script theory and sexual field theory has been used, together with Norbert Elias theories on the relationship between the established and the outsiders. The results indicate that Grindr is a refuge and safe space for homo- and bisexual men and queer persons from the social and sexual norms that prevails in a heteronormative society. As such, Grindr could be understood as a social and sexual field of its own, in which interpersonal scripts and negotiations are crucial for establishing contacts of various kinds. There is also a remarkable sexual stratification based on various sexual capitals that the users of Grindr use to position themselves in relation to each other in order to be regarded as desirable. One consequence of these “structures of desire” is that some personal and bodily qualities often are regarded in a less favourable way, sometimes with stigmatization and marginalization of groups of people as dire consequences of these structures of sexuality. There’s also a remarkable distinction, resistance and ambivalence against the heteronormative society and its cultural scenarios, but at the same time it was a necessary part in the collective self-image of being an outsider group.
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Dobson, Diana. "Habitat-specific genetic and phenotypic differentiation in juvenile coho salmon." Thesis, 1999. http://hdl.handle.net/2429/9270.
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Juvenile coho (Oncorhynchus kisutch) will spawn and have their offspring reared in very
different habitat types in coastal British Columbian streams. For instance, some utilize main
channel river areas whereas others take advantage of off-channel habitats. However, during
winter, juveniles produced in the main channel areas are believed to move into off-channel
habitats for reasons of protection. These main channel juveniles tend to be much larger at the
start of winter than the off-channel resident juveniles. It is possible that these two size morphs
reflect genetic differentiation that would indicate either the fine-scale population structure or
heritable growth-related differences between individuals using different habitats. On the other
hand, the variation may simply reflect phenotypic plasticity. There is little understanding of the
correspondence between neutral molecular genetic variation and adaptive variation, yet patterns
of molecular variation are most often used to develop management plans directed towards
conserving genetic diversity in salmon populations. This study describes variation for both
microsatellites (neutral genetic markers) and growth, presumably an adaptive trait, in closely
located populations of coho salmon.
The genetic basis of the observed size variation was explored by studying juvenile coho from the
Mamquam River. After 6 months rearing in a common environment, no size differences were
observed between juveniles originating from different habitats. More variation for size was
observed between individuals sampled from within habitat types than was observed among
habitats. This result suggested that the size variation is a result of phenotypic plasticity
associated with environmental differences in rearing habitat. It does not exclude the possibility
that variation for growth among individuals is associated with adaptive differences on a
microhabitat scale. Microsatellite analysis revealed fine-scale population structure within the
Mamquam River resulting from either founder effects associated with channel colonisation, the
existence of separate races, or sampling bias. Heritability for growth over the six-month rearing
period and size were estimated by a novel technique that uses molecular marker similarity to
infer relatedness. Positive co-variances were observed between relatedness and phenotypic
similarity for growth rate and initial size indicating heritability for these traits.
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Warren, Robert J. "Linking understory evergreen herbaceous distributions and niche differentiation using habitat-specific demography and experimental common gardens." 2007. http://purl.galileo.usg.edu/uga%5Fetd/warren%5Frobert%5Fj%5F200708%5Fphd.
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MORRIS-POCOCK, JAMES A. "PHYLOGEOGRAPHY OF BROWN AND RED-FOOTED BOOBIES: A COMPLEX HISTORY OF ISOLATION AND GENE FLOW." Thesis, 2012. http://hdl.handle.net/1974/7164.
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Speciation is an important process that is responsible for the generation of biodiversity on Earth. The importance of gene flow during speciation is hotly debated; however, it can be investigated by studying the process of intraspecific population differentiation. Here, I investigate the mechanisms that influence population differentiation and gene flow in brown (Sula leucogaster) and red-footed boobies (S. sula). These species are congeneric, broadly sympatric, and ecologically similar; however, they differ in their marine habitat preference (inshore vs. pelagic). I hypothesized that: (i) gene flow is restricted by major physical barriers in both species, and (ii) gene flow in the absence of physical barriers is more prevalent in red-footed boobies due to their pelagic marine habitat preference.
First, I characterized the structure and function of the booby mitochondrial genome. Using extensive DNA sequencing and phylogenetic methods, I found that boobies have tandemly duplicated mitochondrial control regions that evolve in concert. I suggest that concerted evolution of duplicated control region may be common in seabirds.
To quantify matrilineal population genetic structure and gene flow, I sequenced one control region in 513 brown and red-footed boobies. Both species exhibited strong population genetic structure that was attributable to continental barriers to gene flow such as the Isthmus of Panama. In the absence of physical barriers, gene flow was more prevalent in red-footed boobies. I also used microsatellite and nuclear intron loci to perform multilocus phylogeographic analyses of brown and red-footed boobies. Individuals of both species could be grouped into four genetic populations that corresponded to oceanographic regions. In red-footed boobies, gene flow following secondary contact of previously isolated lineages was common, perhaps due to a pelagic habitat preference. In brown boobies, major genetic populations apparently diverged in the absence of gene flow. Despite this, Isla San Benedicto in the Eastern Pacific is a site of secondary contact between brown booby lineages that diverged approximately one million years ago, and hybrids are apparently fertile. These findings suggest that gene flow following secondary contact may be an important, but overlooked, component of speciation.Thesis (Ph.D, Biology) -- Queen's University, 2012-04-28 17:28:53.302
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Hadi, Susilo. "Niche differentiation of two sympatric colobines, Simias concolor and Presbytis potenziani on the Mentawai Island of Siberut, Indonesia." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF8E-1.
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Kupers, Stefan Jonathan. "The Soil Moisture Niche in a Moist Tropical Forest – A Demographic Approach." 2019. https://ul.qucosa.de/id/qucosa%3A37543.
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Water availability affects tree species performance and distributions in tropical forests. However, there are no studies that have measured detailed spatial variation in soil water availability within a tropical forest. This limits our understanding of how water availability shapes the demography and distributions of tree species within tropical forests. In this dissertation, I measured detailed spatial variation in soil water potential (SWP), the relevant measure of water availability for plant performance, in the seasonal tropical moist forest of the 50-ha Forest Dynamics Plot on Barro Colorado Island, Panama. In Paper 1, I mapped spatial variation in SWP across the 50-ha plot in various stages of the dry season using information on topography, soil type, dry season intensity and more. In Paper 2, I quantified the soil moisture niches of species in terms of demographic responses (growth and mortality) and species distributions. I related seedling growth and mortality responses to SWP of 62 species to their distributional centre along the SWP gradient, using data from 20 years of annual seedling censuses across 200 seedling census sites. I found that species that grew faster (slow) with increasing SWP were more common on wetter (drier) parts of the SWP gradient. Moreover, wet-distributed species grew faster on the wet side of the SWP gradient than dry-distributed species. Mortality was unrelated to species distributions but decreased strongly with seedling height. These findings indicate that species with a growth advantage with respect to SWP grow faster out of the vulnerable small size ranges, reducing their mortality in later seedling stages and thus shaping species distributions indirectly. This mechanism is a form of niche differentiation that contributes to species coexistence. In Paper 3, I related seedling growth and mortality responses to spatiotemporal variation in water availability with responses to light availability, another highly limiting resource in tropical forests. I found an interspecific trade-off in responses to shade versus inter-annual drought (dry season intensity): species that performed relatively well in the shade performed worse during more severe dry seasons and vice versa. This trade-off enables coexistence, because species are adapted to perform well under either shade or drought. In sum, water availability contributes to the maintenance of the high diversity of tropical forests through hydrological niche differentiation and a trade-off between performance in shade versus drought. Future work can use my SWP maps and species responses to SWP to identify the functional traits that underlie the species responses and improve Dynamic Global Vegetation Models. Finally, my work facilitates the prediction of future species composition, diversity and ecosystem functioning of tropical forests with shifts in rainfall patterns caused by climate
change.
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Lenz, Erin Jennifer. "Rhizobial T-RFLP analysis for differentiating soils and habitats." Diss., 2008. http://proquest.umi.com/pqdweb?did=1606926031&sid=2&Fmt=2&clientId=3552&RQT=309&VName=PQD.
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