Dissertations / Theses on the topic 'Breeding'

The aim of the study was to attempt to identify prebreeding Fulmars and study their behaviour and look at their recruitment and intermittent breeding in general. Over 300 unringed Fulmars of unknown breeding status were caught and ringed during the study but it was not possible to positively identify a prebreeder from breeders. By looking at attendance at colonies throughout the year at confirmed nest-sites and potential nest-sites it was concluded that non-breeding birds were present throughout the prebreeding period although confirmed nest-sites were occupied more often and for longer. Also by looking at individually marked birds and comparing Fulmars of unknown breeding status with birds known to have bred, it was concluded that the latter category arrived earlier in the year in general. Fulmars not known to have bred before were more mobile within the colonies than breeding birds but little was established about dispersal to other colonies except one bird of unknown breeding status ringed on Eynhallow, Orkney, which was recovered at a colony in the Faeroes. The number of unringed Fulmars associated with Eynhallow but not breeding there was estimated about 1400-3100 birds. Intermittent breeding of Fulmars was found to fluctuate considerably between years as did index of recruitment and these two were negatively correlated. On average 28-29&'37 of fulmars which have bred before do not breed each year and that proportion correlated negatively with proportion of eggs hatching. Gaps in the breeding history lasting more than one year were often followed by a change in mate and/or nest-site. An attempt was made to experimentally prevent ten established pairs from breeding by blocking their sites. Time of loss of site was found to be important and the effects of losing the site could last more than one breeding season.

Like many species, Florida's population of Northern Crested Caracaras (Caracara cheriway, hereafter "caracara") is likely declining due to loss of breeding habitat. Consequently, management-oriented restrictions on landscape modification are applied where breeding occurs, but management rarely is extended beyond breeding areas. Focusing management on breeding areas can be effective if all caracaras occupy breeding areas, all breeding areas are detected, and no intermittent breeding occurs. Management may not operate as intended if any of these criteria are unmet. To explore this possibility, I investigated the movement, habitat, survival, and social biology of non-breeding caracaras. I also investigated long-term occupancy of breeding habitat, and factors contributing to detection of breeding. Non-breeding caracaras occupy areas much larger than individual breeding territories, particularly during breeding seasons. Pastures occupied by cattle were the most used habitat, but non-breeding caracaras also occupied habitats atypical of breeding areas. Specifically, citrus groves were occupied extensively, and row crops were used particularly during breeding seasons. Non-breeding caracaras also shared communal roosts, sometimes with hundreds of conspecifics, and roosts were occupied year-round. Survival of non-breeding caracaras was lowest during breeding seasons. Adult non-breeding caracaras persisted in groups for multiple years without establishing breeding territories. This implies that breeding habitat is limited and saturated. Given the proportion of adults in groups, adults also were the first to find carrion more often than expected. Apparently, young caracaras benefit from grouping by following adults. I found caracaras at all sampled breeding areas where nests were originally documented during the 1990s, and found nests at 83% of territories where nests likely existed. I also found that observer experience, visit start time, and weather affected the probability that a nest would be detected. Thus, not all caracaras occupy breeding areas, and not all breeding attempts are likely to be detected. Long-term occupancy of breeding areas should render annual verification of nesting unnecessary as a trigger for maintaining management actions. Rather management should persist even without confirmation of annual breeding. Caracara management also may be optimized through supporting the non-breeding population by maintaining a matrix of cattle pasture and citrus groves, particularly around roosts.
Ph. D.

The Cerulean Warbler (Dendroica cerulea) is a Neotropical migrant bird species which is experiencing severe population declines. This study fills in gaps in the information available concerning Cerulean Warbler territoriality and breeding in a site in southeastern Indiana. During the summers of 2002 and 2003, 51 territories were mapped, with an average territory size of 0.21 hectares. Differences existed between territories and random sites for canopy cover, slope, canopy height, number of trees, diameter at breast height (DBH), the number of trees between 3 - 7.9 cm DBH, the number of trees between 8 - 14.9 cm DBH, the number of trees between 15 - 22.9 cm DBH, and the number of trees > 38 cm DBH. Nest productivity was very low in the study area, suggesting that Big Oaks National Wildlife Refuge was a sink population of Cerulean Warblers during the two years of the study.
Department of Biology

Six species of Meconopsis were investigated for self-fertility and cross compatibility in order to incorporate desirable characters from both parents. The six species used were: M. cambrica, M. villosa, M. quintuplinervia, M. betonicifolia, M. horridula, M. aculeata. Chromosome counts were made: M. cambrica, n=14; M. villosa, n=16; M. quintuplinervia, n= c.42; M. betonicifolia, n=40; M. horridula, n=28 and M. aculeata, n=28. Interspecific compatibility was correlated with differences in ploidy level between parents. All crosses made except M. cambrica x quintuplinervia set seeds. M. cambrica, M. betonicif olia, M. horridula and M. aculeata are self-compatible. Pollination mechanisms and the likelihood of apogamy were investigated in M. betonicifolia. No apogamy was found and insects are the likely pollinators for this species. As some of the species do not flower at the same time, pollen staining, pollen germination and storage conditions for the six species were studied. Experimental alteration of flowering periods through controlling temperatures and day-lengths for M. betonicifolia was also carried out. This part of the project shows: (1) pollen stainability (stained by lactophenol cotton blue) for the six species was 85% or more; (2) pollen of all six species except M. quintuplinervia germinated on an agar medium containing sucrose (5 g 1⁻¹) and H₃BO₃ (0.1 mg 1⁻¹); (3) pollen germination percentage decreased with storage time in a desiccator at 4-6°C; and (4) long daylength (16 h) was suitable for growth and flowering of M. betonicifolia. High temperature (17°C) induced earlier growth and flowering than low temperature (6°C) in M. betonicifolia. Because of difficulties in vegetative reproduction and seed storage, in vitro establishment of M. betonicifolia was investigated. The unopened capsule sterilization method was used. The seeds in the capsule germinated on Murashige and Skoog medium. Derooted seedlings, hypocotyls and seedling roots from seedlings raised on sterile artificial medium were used as explants for the in vitro establishment. This experiment shows that half strength Murashige and Skoog medium is suitable for in vitro culture of this species. The cytokinin:auxin ratio and growth regulator concentration were found to control morphogenesis of M. betonicifolia in vitro. Derooted seedlings cultured first on nutrient medium containing N⁶-benzyladenine (BA) and kinetin (Kn) differentiated more multiple meristems than those originally cultured on medium containing N⁶-(2-isopentenyl)-adenine (2ip) after being transferred into medium containing 2ip. Multiple meristems were divided and proliferated on medium containing 0.2 mg 1⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D), 5 mg 1⁻¹ 2ip and 1 mg 1⁻¹ BA. Seedling roots and hypocotyls formed callus on media containing 1, 5 and 10 mg 1⁻¹ 2,4-D.
Land and Food Systems, Faculty of
Graduate

The production of new rose cultivars by sexual crossing is problematic and time consuming due to sexual incompatibility. the failure of seeds to genninate. and to a limited gene pool. Biotechnology provides an obvious alternative for the creation of genetic novelty in rose. This thesis focuses on the development of novel approaches, based on embryo rescue, pollen cryopreservation, protoplast and transformation technologies. A reproducible embryo rescue technique was developed in which embryos were excised and genninated on agar solidified medium containing a basic salt mixture and carbohydrate. The choice of carbohydrate and the growth conditions employed were demonstrated to markedly affect the percentage germination and subsequent plantlet development. This technique was used to greatly increase the production of F, hybrid progeny when compared to conventional germination methods. The failure of sexual crosses between several English rose cultivars was shown to be due to a combination of low pollen viability and to the operation of a pollen-style incompatibility mechanism (probably of the gametophytic self-incompatibility type). Degree of flower opening and method of pollen dehiscence were shown to significantly affect pollen viability. A technique was developed for the effective cryopreservation of English rose pollen. Using this technique it was possible to store pollen at ultra-low temperatures without any significant loss in viability. Such a technique compared favourably with conventional techniques (refrigeration and freezing) in which a loss in viability over time was demonstrated to occur. In vitro shoot cultures of English rose were established on MS-based media containing BAP. GA3 and NAA following the treatment of explants with an antioxidant solution to negate the effects of phenolic oxidation. The production of callus was shown to be genotype dependant and lacked regeneration potential. Rhizogenic responses were observed in leaf discs of two cultivars however shoot regeneration was not observed. Using a variety of enzyme mixtures it was possible to isolate protoplasts from both In vitro leaf material and from cell suspensions. Both mesophyll and cell suspension derived protoplasts were cultured to a microcallus stage. Plating density, growth regulator concentration and the use of antioxidants were all demonstrated to have a significant effect on the protoplast plating efficiency. Rhizogenesis was achieved from mesophyll protoplast-derived calli. Protoplasts, sometimes labelled with a fluorescent marker, were subjected to both chemical and electrofusion. Using micromanipulation, heterokaryons, formed during electrofusion, were recovered. Such heterokaryons, when cultured. underwent division and formed microcalli which subsequently developed into calli. The hybrid nature of such calli were conftrmed by isozyme analysis, determination of ploidy level and RAPD analysis. The introduction of a plasmid containing a gus marker gene into zygotic embryos of English rose was shown to be possible. This was achieved by microprojectile-mediated DNA delivery using a laboratory built electrical discharge device. The efficiency of this technique was influenced by the concentration of microprojectiles and DNA used. And by firing distance and choice of DNA construct. The relevance of this study and its applications, in the context of rose breeding are discussed.

Five experimental strains and Pima S-6 were grown in seven Regional Tests across the Pima belt in 1986. P67 averaged highest in yield below 2,500 feet, and P65 averaged highest in yield above 2,500 feet elevation. Overall, Pima S-6 yielded 5% less than P67, the top yielding strain across locations. A new monogenic recessive aberrant leaf mutant in Pima was named wrinkled leaf-2 and assigned the gene symbol wr2.

The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.
In the 1985 Pima Regional Tests, no strain yielded significantly above Pima S-6 at individual test sites. An official release was made for okra-leaf shape, frego bract shape, glandless plant and seed, nectariless, and male-fertility restoration noncommercial germplasm lines of Pima cotton. These germplasm lines incorporating genetic traits with potential economic value may be especially useful in developing parental material for hybrid cotton.

There have been many changes in the United States sheep industry over the years. Decreasing profitability of wool production has shifted the focus of many producers to strictly meat production. In south Texas, extreme high summer temperatures add an additional challenge in raising wool breeds of sheep. Hair sheep are gaining popularity in lamb-only production systems as they are more adapted to hot climates and eliminate shearing costs. The Dorper is the most popular breed of hair sheep throughout Texas due to superior lamb carcasses. Maximizing reproductive efficiency is critical for increasing the profitability of sheep production. Accelerated lambing systems can produce 3 lamb crops every two years versus 1 lamb crop per year. For this to be accomplished, ewes must be capable of breeding early post-partum and at all times of the year. We determined the reproductive characteristics of Dorper ewes. In the absence of a ram, Dorper ewes were anestrous from March until May. We observed considerable variation of ewes when both entering and ending anestrous. During the initial breeding season, 7-d CIDR^® treated ewes, which conceived 1^st service, had a significantly lower mean day of birthing (3.2 ± 2.1 d) compared to (10.1 ± 1.9 d) control ewes, resulting in a shorter lambing duration. During the seasonal anestrous period both CIDR^® treated and control post-partum Dorper ewes were stimulated to ovulate while in the presence of the ram. However, during this time, 9-d CIDR^® treatment significantly shortened both overall ram to lambing interval (152.8 ± 3.2d vs.165.7 ± 3.0 d) and first service ram to lambing interval (149.3 ± 1.3 d vs. 160.7 ± 1.5 d). Fall-born Dorper ewes with known birth dates had a mean age of puberty of 306.5 ± 4.9 d. Fall-born yearlings and spring-born ewe lambs were exposed to a ram during the first fall breeding season following their birth. While no difference was found in overall conception rate, fall-born yearlings had a significantly greater first service conception rate (83.3 %) compared to spring-born lambs (28.6 %). The findings of this study illustrate that Dorper ewes have the potential to be utilized in accelerated lambing systems in south Texas. By achieving a high conception rate post-partum simultaneous to the anestrous season, we were able to maintain an 8 mo lambing interval during the first two breeding season. We conclude that the reproductive attributes of the Dorper ewe makes them an excellent choice for sheep producers throughout South Texas.

Doctor of Philosophy
Division of Biology
Brett K. Sandercock
Impacts of climate change on biological systems include shifts in seasonal phenology. How do migratory animals adjust reproductive decisions as they shift timing of breeding? I investigated patterns of climate change at a network of Arctic sites in Alaska and Canada, and examined the impacts of climate change on the breeding phenology, reproductive performance, and trophic interactions of Arctic-breeding shorebirds. First, I compared the breeding performance of three species, Western Sandpiper, Semipalmated Sandpiper, and Red-necked Phalaropes, at Nome, Alaska, across a 14-year interval. I found that shorebirds responded to a decreasing temperature during laying by delaying timing of breeding. Delayed breeding shortened the incubation duration for two biparental species but extended incubation for a uniparental species. Despite a short Arctic summer, the breeding windows of three sympatric species were temporally distinct. The three species often nested within several meters from each other, but bred under different temperature regimes and adjusted their reproductive output to different sets of environmental factors. Shifts in breeding phenology can disrupt trophic interactions, especially the phenological match between peak prey availability and hatching of shorebirds. Comparing the extent of phenological mismatch between six shorebirds and their invertebrate prey at ten Arctic sites, peak demand of shorebird broods occurred on average 3.8 days (± 13.8) later than local food peaks, and population demand curves overlapped with food curves by 47% (± 14%). Latitudinal and longitudinal gradients in the extent of trophic mismatch were mediated through geographic variation in the seasonal phenology of invertebrates and shorebirds. For individual nests, both more northerly and easterly sites showed greater phenological mismatch with annual food peaks. Delayed emergence of food peaks at more northerly and easterly sites alleviated the extent of phenological mismatch. My multi-site study provides the first evidence that large-scale geographic processes can determine the extent of phenological mismatch in a bitrophic system. Trends of climate change are sensitive to breeding stages and also vary along a longitudinal gradient. Variability in climatic trends in the Arctic, combined with species-dependent responses to local climate change, indicate that it will be challenging to predict the impacts of future climate change.

Hygienic behaviour in the honeybee (Apis mellifera) has been shown to be an effective control mechanism against brood diseases such as chalkbrood and AFB. Chalkbrood has proven to be problematic for the Australian honey industry since it was identified here in 1993. Hygienic behaviour is a much studied trait. Rothenbuhler investigated the genetic basis of hygienic behaviour, proposing a two-gene model to explain the uncapping and removal of dead brood. His elegant experiment remains the textbook example of a behavioural genetic study. Although this model has been challenged, it is still generally agreed that a small number of unlinked genes produce a large effect on hygienic behaviour, that hygienic alleles are recessive and are inherited in a Mendelian manner. Experimental backcross colonies were produced from an inbred hygienic line and an inbred non-hygienic line, both provided by Dr. Marla Spivak, University of Minnesota. These backcross colonies were assessed for hygienic behaviour using a standard assay. Statistical analyses of the field data indicated that the genetic basis of the trait was more complex than either the simple Mendelian and widely accepted two-gene or three-gene models that have been proposed previously. Molecular techniques, linkage mapping and QTL analysis then were employed to determine how many loci directly influence hygienic behaviour and the relative level of influence and location of each locus within the genome of A. mellifera. Full multipoint linkage analysis by Mapmaker v3.0 software produced a new genetic map of the honeybee comprised of 358 marker loci ordered over 25 linkage groups spanning a total distance of 3406.2 cM. The average distance between each marker was 9.5 cM. QTL analysis of the experimental data identified seven putative genetic markers associated with hygienic behaviour. QTLs located on linkage groups 2, 4, 6 and 22 were detected for both overall hygienic behaviour and uncapping behaviour only. Individually, each QTL is of relatively small effect with each explaining only 9% � 15% of the variance in hygienic levels observed. Collectively, the putative QTLs identified here explain 79.4% of the observed variance in the expression of hygienic behaviour. These results indicate that there are many genes of low to moderate effect rather than few genes of large effect involved in this complex behavioural trait. This is typical of inherited quantitative traits which do not exhibit Mendelian phenotypic ratios. DNA extracted from the brood samples taken during testing of commercial stock, and from individual bees identified as either highly hygienic or non-hygienic in a reciprocal backcross experiment, were screened with the candidate markers associated with putative QTLs to test their diagnostic power. Unfortunately, none have produced reliably diagnostic DNA profiles. As we have now shown that hygienic behaviour is a polygenic, quantitative trait, simple diagnostic markers for Rothenbuhler's 'uncapping' and 'removal' genes are unlikely to be achieved. Our results show that the most likely way to improve disease resistance in Australian stock is via traditional methods of recurrent selection. The project was responsible for the importation of new genetic material into Australia from the United States. This hygienic stock has been well received by industry, has been widely disseminated, and incorporated into local breeding programs. We hope that it has lead to a general improvement in the level of disease resistance in Australian commercial bees.

Designing power-viruses, programs created for consuming as much power as possible, is a non-trivial task. This task is often performed by hand and is both time-consuming and complicated. As power-viruses may be used for testing the stability of hardware it is important that the viruses are well designed. This thesis presents an approach to automate the process of creating power-viruses with the help of Artificial Intelligence. Furthermore, the process of generating these programs will be performed on real hardware rather than using simulators. The hardware considered in this thesis is the Pandaboard ES and Raspberry PI, two boards built around ARM-based System-on-a- chip's. During the thesis, power-viruses have been successfully generated on both the Pandaboard ES and Raspberry PI. On the Pandaboard ES up to a 7.1% power-consumption increase has been achieved when compared with hand-written power-viruses for the same hardware. The process used in this thesis is easy to use and reduces the effort required for designing a power-virus.

Captive carnivores pose a challenge for conservationists and institutions alike, presenting many problems that range from diseases to poor welfare and unsuccessful breeding. Available databases of captive populations are rich sources of information that can help determine which factors can affect breeding success and the real potential of these populations in conservation programmes. Some species, such as tigers Panthera tigris, seem to preserve in captivity the same reproductive parameters seen in wild animals, making captive individuals extremely useful in the research of reproductive biology, that can be applied in evolutionary and physiological studies of the order Carnivora. Specific reproductive characteristics, mainly connected with the altriciality of the young, can make some species more prone to lose young in captivity than others, and these factors must be taken into consideration when developing ex situ conservation programmes. Infant mortality in captivity seems to be primarily caused by inadequate maternal behaviour, which can be connected to biological factors as well as to individual characteristics such as origin and rearing methods. Maternal infanticide, either passive or active, is also affected by biological and ecological characteristics of the species, and there may be an effect of the origin of the females, i.e. if they were wildcaught or captive-born. Housing conditions and individual history affect infant mortality, with females that suffered transfer between institutions exhibiting lower breeding success. Also, institutions with thriving research programmes presented higher infant mortality overall, independently of their latitude or management system, which can indicate an effect of human interference. Further research, both in the wild and in captivity, is needed to fully understand the factors affecting breeding success of captive carnivores.

Parasites are important drivers of ecological and evolutionary processes in their hosts. However, hosts often differ in how they are affected by parasitism, which can be important in how parasite effects on individuals scale up to the population level. Hosts may differ intrinsically in their susceptibility to parasitism, and extrinsic factors may impose constraints on how hosts allocate resources between immunity, maintenance and reproduction, thereby further affecting their ability to cope with infection. These extrinsic factors include the host’s ecological environment, for example food availability or weather, and its social environment, that is its interactions with conspecifics. This is particularly true during a reproductive attempt when individuals interact closely with other family members. Not only might immediate impacts of parasitism differ between and within parents and offspring, but the direct effects of parasitism on a host could have further indirect consequences for other family members through their behavioural interactions with parasitised individuals. The distribution of direct and indirect effects among all family members could affect the outcome of the breeding event and individuals’ future performance. However, teasing apart these various avenues of parasite impacts on families may be difficult if parasite burden or susceptibility is correlated between family members. In this thesis, I explore the consequences of parasitism for different family members of the European shag Phalacrocorax aristotelis infected with gastrointestinal nematodes, over a range of ecological conditions. In chapter 2, I demonstrate that chicks’ responses to anti-parasite treatment across four years vary between siblings and with environmental conditions, which may be mediated by resource allocation among siblings. In chapter 3, I explore how costs of parasitism are distributed among the whole family by simultaneously treating chicks and/or parents with an anti-parasite drug and measuring the outcomes for all family members. Treatment has a more marked effect for the non-treated generation than for the treated individuals, suggesting that parasitism may have important indirect costs. In chapter 4, I investigate whether within-brood variability in the effects of anti-parasite treatment and its cross-generational impacts are mediated by behavioural change, and show that chick treatment but not parent treatment influences several aspects of behaviour in the nest. In chapter 5, I demonstrate that the impact of chick anti-parasite treatment on parents persists beyond the breeding attempt, with parents of treated chicks foraging less overwinter and breeding earlier the following year, whereas there is no persistent effect of parents’ own anti-parasite treatment. Lastly, I provide an appendix examining the parasitology of the system in detail, including an assessment of in situ and proxy measures of worm burdens of chicks. This thesis demonstrates that parasitism can be a key component, previously overlooked, of reproductive performance in seabirds, a group that plays an important ecological role as apex predators and thus indicator species of the marine environment.

Recent trials of Antirrhinum majus cultivars have revealed a wide range of susceptibility to rust (Puccinia antirrhini). The best plants were used as parents in a breeding programme to produce a useful level of durable field resistance. The F1 generation was self-pollinated but the F2 to F4 were selectively cross-pollinated within lines. The segregating generations were grown outdoors at two sites in Surrey, where they were subject to natural rust epidemics encouraged by the use of spreader rows. Individual plants were selected for rust-resistance and horticultural quality. By the F4 generation, lines showed greater resistance to rust than existing varieties and were becoming uniform in flower colour, growth habit and horticultural quality. Many floral abnormalities arose, especially in the F3. Their expression was usually highly variable and was enhanced by environmental stress. Tests of rust isolates against individual antirrhinum plants showed that there is considerable genetic variation within the rust population. Some monitoring of resistant varieties is desirable to identify future changes in the rust population. The spread of spores between widely spaced patches of susceptible host was simulated using a computer, which indicated that small, isolated patches may escape infection. The effect of rate-reducing resistance is increased when plants are widely separated. This is in agreement with practical experience. The urediniospores of Puccinia antirrhini cannot survive the winter in Britain and, though teliospores are regularly produced, no alternate host is known. However, overwintered antirrhinum plants produce viable urediniospores which start epidemics in early summer: there is no need to postulate an alternate host in the British Isles. Treating antirrhinum as a summer annual might be an important hygienic measure, reducing the local build up of inoculum early in the season. Acceptable control of rust should be possible, provided only the more resistant varieties are grown.

Die Arbeit beschreibt ein stochastisches Simulationsprogramm zur Modellierung von Honigbienenpopulationen unter Zuchtbedingungen. Dieses Programm wurde neu implementiert um unterschiedliche Selektionsstrategien zu evaluieren und zu optimieren. In einer ersten Studie wurde untersucht, inwiefern die Vorhersagen, die das Programm trifft, vom verwendeten genetischen Modell abhängt. Hierbei wurde festgestellt, dass das Finite-Locus-Modell dem Infinitesimalmodell in Langzeitstudien vorzuziehen ist. Eine zweite Studie beleuchtete die Bedeutung der sicheren Anpaarung auf Belegstellen für die Honigbienenzucht. Hier zeigten die Simulationen, dass die Zucht mit Anpaarungskontrolle derjenigen mit freier Paarung von Königinnen deutlich überlegen ist. Schließlich wurde in einer finalen Studie der Frage nachgegangen, wie erfolgreiche Zuchtprogramme bei der Honigbiene langfristig nachhaltig zu gestalten sind. Hierbei sind kurzfristiger genetischer Zugewinn und langfristige Inzuchtvermeidung gegeneinander abzuwägen. Durch umfangreiche Simulationen konnten für verschiedene Ausgangspopulationen Empfehlungen für eine optimale Zuchtintensität auf mütterlicher und väterlicher Seite gefunden werden.
The present work describes a stochastic simulation program for modelling honeybee populations under breeding conditions. The program was newly implemented to investigate and optimize different selection strategies. A first study evaluated in how far the program's predictions depend on the underlying genetic model. It was found that the finite locus model rather than the infinitesimal model should be used for long-term investigations. A second study shed light into the importance of controlled mating for honeybee breeding. It was found that breeding schemes with controlled mating are far superior to free-mating alternatives. Ultimately, a final study examined how successful breeding strategies can be designed so that they are sustainable in the long term. For this, short-term genetic progress has to be weighed against the avoidance of inbreeding in the long run. By extensive simulations, optimal selection intensities on the maternal and paternal paths could be determined for different sets of population parameters.

This thesis was made in collaboration with the Baltic Seabird Project with the purpose of evaluating the possibilities of using cameras to monitor the fledging success of Common Guillemots on Stora Karlsö. Fledging success is measured from the time the egg is laid, hatched, until the chick is 15 days old and considered ready to leave the nest. Camera monitoring means that the breeding area where the birds reside is photographed at a predetermined interval to attempt to capture the offspring to determine its survival. The study was conducted on Stora Karlsö by installing cameras in the artificial breeding shelf, Auk Lab, and determine how well the method works. Whether the offspring can be caught on camera was the main question, with a secondary question addressing the differences from the traditional monitoring method which is done by daily controls by one person on site. The results show that camera monitoring can be a useful method. It is possible to observe the off-spring, but distance and angle are important factors affecting image quality. Power supply and the memory card size are important factors that decide whether time savings can be made compared to the traditional method. Further development of the routines for camera monitoring is necessary to create a reliable data collection
Studien gjordes i samarbete med Baltic Seabird Project med syftet att undersöka möjligheten att använda kameror för att övervaka häckningsframgång hos Sillgrissla på Stora Karlsö. Häckningsframgång definieras som tiden från att ägget läggs, kläcks, och ungen överlever i 15 dagar då den anses vara redo att lämna boet. Övervakning med kameror innebär att häckningsytan där fåglarna sitter fotograferas med ett bestämt tidsintervall för att försöka fånga avkomman på bild och därmed se att den har överlevt. Undersökningen har genomförts på Stora Karlsö genom att installera kameror i den konstgjorda häckningshyllan Auk Lab och bedöma hur väl metoden fungerar. Huruvida avkomman fångas på bild eller inte var den huvudsakliga frågeställningen, med en sekundär frågeställning som rör skillnaden mellan den traditionella insamlingsmetoden som genomförs genom att en person dagligen kontrollerar fåglarna. Resultaten visar att kameraövervakning kan vara en användbar metod, då det går att fånga avkomman på bild men avstånd och vinkel är några av de avgörande faktorerna för att framgångsrikt kunna observera avkomman. Strömtillförsel och minneskortets storlek är avgörande faktorer för att göra vinningar tidsmässigt jämfört med den traditionella metoden. Fortsatt utveckling av rutinerna för kameraövervakning är nödvändigt för att få en pålitlig datainsamling.  2

Bibliography: pages 187-191.
The foraging of breeding Jackass Penguins Spheniscus demersus was studied in and around southwestern Cape Province, Saldanha Bay (33⁰ S, 18⁰ E), South Africa. Penguins are difficult to observe at sea. Hence, I devised a number of new techniques for studying the foraging behaviour of Jackass Penguins at sea. I built electronic and autoradiographic remote-sensing devices to measure swimming speed, distance travelled and time spent at each depth by foraging Jackass Penguins. Penguin swimming speed was reduced in proportion to the cross-sectional area of the devices, and results derived from birds wearing the devices had to be interpreted accordingly. Penguins do not regurgitate their stomach contents when handled, so I constructed a wet-offloading stomach pump which extracted 100% of the stomach contents. Using this pump, I determined that the rate of digestion of fish and squid by Jackass Penguins differed. Care is needed in diet interpretations where both fish and squid are major food items.

Breeding objectives were developed for Targhee sheep at different levels of prolificacy and triplet survival. Economic weights (EW) were derived for estimated breeding values (BV) from National Sheep Improvement Program genetic evaluations for 120 d weaning weight (WW), maternal milk (MM), yearling weight (YW), fleece weight (FW), fiber diameter (FD), staple length (SL), and prolificacy (PLC; lambs born/100 ewes lambing). A commercial flock was simulated, accounting for nonlinear relationships between performance and profit. Ewes were assumed mated to sires of specified BV and profit was derived from lifetime performance of lambs and replacement females from that lamb crop. Economic weights were determined as change in profit from use of sires with BV that were one additive standard deviation above the mean for each trait [1.98 kg for WW, 1.62 kg for MM, 2.90 kg for YW, 0..36 kg for FW, 0.99 microns for FD, 0.74 cm for SL, and 17.58 lambs/100 ewes for LC], while holding all other BV at breed average. Separate breeding objectives were derived for different ways of meeting increased nutrient needs (P = purchase hay, R = rent pasture, and L= limited flock size) and for different market lamb values (D = discounting lamb value for heavy weights, ND = no discount for heavy lambs). Based on replicated simulations, relative EW did not vary with prolificacy or triplet survival (P > 0.15) but were affected by feed costs and lamb market values (P < 0.01). Selection indexes were derived within and across simulated scenarios, and correlation (r) among indexes of > 0.90 indicated that an index could be used across multiple scenarios with little loss of selection efficiency. Indexes derived within feed cost scenarios (P, R, and L) and lamb value scenarios (D, ND) were strongly intercorrelated (r > 0.97). Correlations among average indexes for feed cost scenarios (0.97 for R and P, 0.70 for R and L; 0.85 for P and L) indicated that two feed cost scenarios could be used depending on whether winter forage was limited (L) or not (NL). The correlation between average indexes for these two scenarios was 0.78. Indexes were presented for combinations of feed cost and lamb value scenarios. Two indexes were suggested, representing the scenarios that apply to a large portion of Targhee producers. These indexes were for discounting heavy lambs with limited winter forage (D-L: 1.0 WW + 0.14 MM __ 0.76 YW + 1.22 FW __ 0.36 FD - 0.09 SL + 0.25 LC) and discounting heavy lambs with additional available forage (D-NL: 1.0 WW + 0.24 MM __ 0.34 YW + 1.65 FW __ 0.41 FD - 0.14 SL + 0.33 LC). For a standardized selection differential of one for the index, the expected changes in mean index value were $2.17 and $1.92 per ewe per generation for D-L and D-NL, respectively.
Master of Science

The interaction effects of genotype and nutrition on the performance of sows during lactation is still poorly understood; this series of experiments explored the factors contributing to breed differences in lactational performance and the development of appropriate feeding strategies. Two extreme types of sow were used in these experiments; lean pure-bred White sows (W: Large White and Landrace) and a prolific but fatter Meishan synthetic damline (M: 50% Meishan genes). M sows had higher numbers of piglets, a different feed intake curve and produced more milk with a higher fat content compared to W breed types. Their response to dietary protein was different for the two breeds; the Meishan sows, with higher initial levels of body fat reserves, used the extra protein to increase milk production. The White sows did not partition the extra protein into milk but used it to conserve their own maternal body reserves and improved their weaning to conception interval. The breed differences in sows performance were found not to be solely due to differences in litter size or piglet genotype or maternal body fat reserves. M sows showed better maternal behaviour with lower activity and shorter suckling intervals. It can be concluded from these experiments that Meishan synthetic sows are inherently better mothers, and the way in which sows of different breed types partition feed nutrients during lactation is very different. A dietary lysine concentration of 9 g/kg (giving daily intakes of 53-61 g/day at 98-111 MJ DE/day) optimised lactational and rebreeding performance in both breed types.

The aim of this thesis was to identify molecular markers associated to tolerance to biotic and abiotic stresses in sugar beet. Sugar beet is one of the world’s most important crops currently supplying around 20% of the sugar consumed worldwide. The crop is damaged by many adverse environmental conditions and the development of varieties that require fewer technical inputs for cultivation is one of the main research demands. To achieve this, sugar beet breeding is focusing on genetic improvement programs assisted by molecular markers. These methods are making selection procedures more rapid, accurate and less expensive. The development of a large set of SNP markers can facilitate the identification and exploitation of genes affecting important traits, such as resistance to biotic and abiotic stresses. Several techniques are used to enable SNP marker discovery in plants. Among these, the Restriction-site Associated DNA (RAD) technique is widely used. The RAD technique is based on acquiring and characterizing the genomic regions adjacent to a set of specific restriction enzyme recognition sites. Bulk Segregant Analysis (BSA) is a method to identify DNA markers linked to genes or genomic regions of interest. DNA samples from individuals showing contrasting phenotype are compared with a large set of molecular markers to select those linked to the trait of interest. The first part of the thesis presents a panel of 192 SNPs for effective sugar beet genetic diversity assessment using a recently released platform (QuantStudio 12K Flex system coupled with Taqman OpenArray technology) that has key elements required for high-throughput SNP genotyping. In the second part, the 192 SNPs were used to assess the phylogenetic relationship between Rizor and Holly (Rz1) resistance sources. The molecular results demonstrate that the resistances to rhizomania used by farmers over the last 30 years derived from sea beet collected in the Po River Delta. Analysis of molecular variance and principal coordinate analysis confirmed that Rizor and Rz1 couldn’t be distinguished as separate sources of resistance. In the third part, a marker linked to the first nematode tolerance gene (HsBvm-1) from Beta vulgaris ssp. maritima valuable for high-throughput marker-assisted selection was identified and mapped on chromosome 5. The fourth and fifth parts focus on resistance to abiotic stresses that compromise sugar production. Premature flowering or bolting, due to cold temperatures in early spring, is an undesirable characteristic that causes severe sugar yield losses and interferes with harvesting. A new locus involved in the genetic determination of bolting tendency was studied and a SNP marker associated with bolting tendency was found on chromosome 6. SNP location on the sugar beet genome confirms the association with flowering since it was mapped in a matrix metalloproteinase gene that causes late flowering and early senescence in Arabidopsis thaliana. Given the close and positive relationships between yield and root morpho-physiological traits, a BSA was conducted to identify a SNP marker linked to root elongation rate in sugar beet. SNP10139 was mapped on the peptide transporter gene influencing root elongation in Arabidopsis thaliana. The result suggests that SNPs developed in these studies could serve as a source for genotyping of sugar beet parental lines and varieties, with relevant impact on breeding program decisions.
Lo scopo della tesi è stato quello di identificare marcatori molecolari associati alla tolleranza a stress biotici e abiotici in barbabietola da zucchero. La barbabietola attualmente produce circa il 20% dello zucchero mondiale. Uno dei maggiori obiettivi del miglioramento genetico è lo sviluppo di varietà che richiedano un sempre più basso utilizzo di mezzi tecnici per la coltivazione. Per raggiungere questo scopo, il breeding della barbabietola si è focalizzato su programmi di miglioramento genetico assistito da marcatori molecolari. Queste tecniche stanno rendendo la procedura di selezione più rapida, precisa e meno costosa. Lo sviluppo di un ampio set di marcatori SNP (Single Nucleotide Polymorphism) può facilitare l’identificazione e l’utilizzo di geni che controllano caratteri importanti di resistenza agli stress biotici e abiotici. Molte sono le tecniche che vengono utilizzate per lo sviluppo di marcatori SNP nelle piante. Fra queste, la tecnica Restriction-site Associated DNA (RAD), impiegata nel presente lavoro di tesi, è ampiamente diffusa e si basa sull'acquisizione e la caratterizzazione di regioni genomiche adiacenti a siti di restrizione riconosciuti da specifici enzimi. E’ stata utilizzata anche l’analisi dei segreganti riuniti (BSA) per identificare marcatori del DNA legati a geni o a regioni genomiche di interesse. Nella prima parte della tesi è stato messo a punto un set di 192 SNP per la genotipizzazione ad alta processività di accessioni di barbabietola utilizzando una recente piattaforma (QuantStudio 12K Flex system) rilasciata da Life Technologies, Inc. (Carlsbad, CA, USA). Nella seconda parte della tesi i 192 SNP sono stati utilizzati per determinare la relazione filogenetica tra le due fonti di resistenza alla rizomania Rizor e Holly (Rz1). L’analisi della varianza e delle componenti principali hanno confermato che le fonti Rizor e Holly sono indistinguibili. I risultati molecolari hanno dimostrato che la resistenza usata, dai coltivatori negli ultimi 30 anni, deriva dalle barbabietole maritime collezionate nel delta del Po. Nella terza parte è stato identificato il primo gene di tolleranza ai nematodi (HsBvm-1) in Beta vulgaris spp. maritima e il marcatore molecolare ad esso associato da utilizzare in programmi di miglioramento genetico. La quarta e quinta parte sono state focalizzate sulla resistenza a stress abiotici che compromettono la produzione di zucchero. La tendenza alla prefioritura, dovuta alle basse temperature nelle prime fasi di sviluppo della coltura, è una caratteristica indesiderata che causa gravi perdite nella resa di zucchero e interferisce con la raccolta. Un nuovo locus, implicato nel controllo genetico della tendenza alla fioritura, assieme a un marcatore ad esso legato sono stati mappati sul cromosoma 6. La localizzazione dello SNP sul genoma di riferimento della barbabietola da zucchero ha confermato l’associazione con il carattere della fioritura. Lo SNP è stato mappato in un gene che codifica per una proteina chiamata metalloproteinasi che causa un ritardo della fioritura e una prematura senescenza in Arabidopsis thaliana. Data la positiva e stretta relazione tra la resa in zucchero, il superamento della carenza idrico nutrizionale e le caratteristiche morfo-fisiologiche dell’apparato radicale, un’analisi dei segreganti riuniti è stata condotta per identificare marcatori SNP legati all'accrescimento radicale in barbabietola. Fra i 234 SNP esaminati, lo SNP10139 è risultato associato allo sviluppo radicale. Inoltre, lo SNP è stato mappato in un gene codificante un trasportatore di peptidi che influenza lo sviluppo radicale in Arabidopsis thaliana. In conclusione, gli SNP sviluppati in questo lavoro saranno utilizzati per la genotipizzazione di linee parentali e ibridi di barbabietola da zucchero, con rilevante impatto nei programmi di breeding.

Thesis (MScAgric)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: The objective of this study was to obtain more information regarding the characterisation of Afrikaner (A), Hereford (H) and Simmentaler (S) breeds in an initial crossbreeding programme and subsequent composite development. This involves the estimation of breed additive effects, breed maternal, individual heterotic effects and maternal heterotic effects in the initial crossbreeding phase and the estimation of genetic parameters and prediction of breeding values in later generations for birth weight (BW), weaning weight (WW) and cow efficiency (CE; WW/dam weight" 75 x 100) in an intensive environment under high stocking rates. In the analysis of the initial crossbreeding phase, the S breed direct effects, expressed as deviation from the general mean, were positive (P :s; 0.01) for both BW and WW. Hereford and A breed direct effects were negative (P :s; 0.01) for both BW and WW. Afrikaner direct maternal effects were positive (P :s; 0.01) for both BW and WW. The H direct maternal effect was negative (P :s; 0.05) (- 2.8%) for WW. Simmentaler maternal effect was negative (P :s; 0.01) for BW but non-significant (P ;:::0:.05) for WW. Individual heterotic effects for BW were significant (P:S; 0.01) in H x S (3.5%) and S x A (11.0%) only. Individual heterotic effects were positive (P :s; 0.01) for WW, with that of the H x A (9.8%) and S x A (6.7%) crosses exceeding the H x S (3.1%) cross. Maternal heterotic effects were non-significant (P ;:::0:.05) for both BW and WW. Investigations of the contributions of the A, Hand S during composite development in later generations, respectively, were made to estimate direct heritabilities (h2 a) and maternal heritabilities (h2 m) for BW and WW of the calf and CE of the dam. Calves were born between 1968 and 1993 (n = 52628). Calves of this composite population had varying levels of A, Hand S genes ranging from o to 75%, 0 to 100% and 0 to 96.9%, with an average of 4.3,19.3 and 33.4%, respectively. For the A, direct heritabilities fitting unitrait models were 0.67, 0.53 and 0.19 for BW, WW and CE, respectively, with corresponding estimates of h2mbeing 0.22, 0.36 and 0.58. Genetic correlations between direct and maternal effects (ram)were negative for all three traits, varying from -0.32 to - 0.62. Direct breeding values for BW increased and reached a maximum value at 0.11 proportion of A. The maternal breeding values for BW decreased linearly between 1.6 to 37.5% A proportion and increased linearly between 37.5 to 75% A proportion. For WW, the direct breeding values decreased linearly with increasing A proportion, while the maternal breeding values were not affected by proportion of A. Cow efficiency was unaffected by an increase in proportion of A. For the H, direct heritabilities fitting unitrait models were 0.67,0.52 and 0.21 for BW, WW and CE, respectively, with corresponding estimates of h2mbeing 0.22, 0.36 and 0.60. Genetic correlations between direct and maternal effects (ram)were negative for all three traits, varying from -0.32 to - 0.64. Direct breeding values and maternal breeding values for BW and WW decreased with increasing proportion of H. Direct breeding value for CE increased, while the maternal breeding value for CE reached minimum value at 0.62 proportion ofH. For the S, direct heritabilities fitting unitrait models were 0.66, 0.53 and 0.21 for BW, WW and CE, respectively, with corresponding estimates of h2m being 0.22, 0.36 and 0.59. Genetic correlations between direct and maternal effects (ram)were negative for all three traits, varying from -0.32 to - 0.63. Direct breeding values for BW and WW decreased and maternal breeding values increased with increasing proportion of S. Cow efficiency was unaffected by an increase in proportion of S. The study suggests that in the initial crossbreeding phase, purebred S breeding seems to be the best breeding practice for this environment and that during composite development, high A and H contributions could lead to low BW and WW (except the maternal contribution of the A for BW and WW). The advantage of the S lies more in the maternal contribution than in the direct contribution suggesting that the S is a large-framed maternal line rather than a terminal sire line.
AFRIKAANSE OPSOMMING: 'N WAARDEBEP ALING VAN DIE BYDRAE VAN DIE AFRIKANER, SIMMENTALER EN HEREFORD TYDENS KOMPOSIETE RASONTWIKKELING BY VLEISBEESTE: Die doel van die studie was om inligting aangaande die karakterisering van die Afrikaner (A), Hereford (H) en Simmentaler (S) rasse tydens die oorspronklike aanvangsfase van kruisteling en daaropvolgende komposiet ontwikkeling te verkry. Dit het die beraming van direkte additiewe, individuele heterose, direkte materne en materne heterotiese effekte tydens die aanvangsfase van die kruisteeltprogram, die beraming van genetiese parameters en die voorspelling van die teeltwaardes in latere generasies behels. Die eienskappe wat ingesluit is, is geboortegewig (BW), speengewig (WW) en koeidoeltreffendheid (CE; WW/koeigewigo.75 ). Hierdie kudde is in 'n intensiewe maar onder 'n hoë weidingsdruk omgewing aangehou. Tydens die ontleding van die eerste kruisteeltfase is die direkte additiewe effekte vir die S, uitgedruk as afwyking van die algemene gemiddelde, vir beide BW en WW positief (P ~ 0.01). Direkte additiewe effekte vir die H en A was vir beide BW en WW negatief (P ~ 0.01). Afrikaner materne effekte was vir beide BW en WW (P ~ 0.01) positief. Die H direkte materne effekte was negatief (-2.8%) (P ~ 0.05) vir WW. Simmentaler maternal effekte was ook vir BW negatief (P ~ 0.01), maar nie-betekenisvol (P 20.05) vir WW. Individuele heterose was slegs betekenisvol (P ~ 0.01) vir kombinasies van H x S (3.5%) en S x H (11.0%) vir BW. Individuele heterose was positief (P ~ 0.01) vir WW waar H x A (9.8%) en S x A (6.7%) kruisings dié van die H x S (3.1%) kruising oortrefhet. Materne heterose was vir beide BW en WW nie-betekenisvol (P 2 0.05). Die relatiewe bydraes van die A, H en S is ook tydens komposiet-ontwikkeling bereken. Direkte additiewe oorerflikhede (h2 a) en materne oorerflikhede (h2m) is vir BW en WW van die kalf en CE van die koei beraam. Kalwers in die komposiet kudde, gebore tussen 1968 en 1993 (n = 52628), het variërende vlakke van A, H en S gene. Die samestelling het gevarieer van 0 - 75%, 0 - 100% en 0 - 96.9%, met 'n gemiddeld van 4.3, 19.3 en 33.4%. Vir die A was die direkte erfbaarhede (h2 a), soos deur die passing van 'n enkeleienskapmodel beraam, 0.67, 0.53 en 0.19 vir onderskeidelik BW, WW en CE, met ooreenstemmende beramings van 0.22, 0.36 en 0.58 vir h2 rn- Genetiese korrelasies tussen direkte en mateme effekte (ram)was almal negatief en het tussen -0.32 en -0.62 gewissel. Direkte teelwaardes vir BW het met toenemende A-bydrae gestyg en het 'n maksimum waarde by 0.11 bereik. Die mateme teelwaardes vir BW het lineêr gedaal tussen 1.6 en 37.5% A-bydrae en het weer lineêr tussen 37.5 en 75% Abydrae gestyg. Vir WW het die direkte teelwaardes lineêr met toenemende A-bydrae gestyg, terwyl die mateme teelwaardes nie deur A-bydrae beïnvloed was nie. Koeidoeltreffendheid was nie deur 'n toename in A-bydrae beïnvloed nie. Vir die H was die direkte erfbaarhede (h2 a), soos deur die passing van 'n enkeleienskapmodel beraam 0.67, 0.52 en 0.21 vir onderskeidelik BW, WW en CE, met ooreenstemmende beramings van 0.22, 0.36 en 0.60 vir h2 rn- Genetiese korrelasies tussen direkte en mateme effekte (ram)was almal negatief en het tussen -0.32 en -0.64 gewissel. Direkte teelwaardes en mateme teelwaardes vir BW en WW het met toenemende H-bydrae gedaal. Direkte teelwaarde vir CE het ook met toenemende If-bydrae gedaal, terwyl die mateme teelwaarde 'n minimum waarde by 0.62 H-bydrae bereik het. Vir die S was die direkte erfbaarhede (h2a), soos deur die passing van 'n enkeleienskapmodel beraam 0.66, 0.53 en 0.21 vir onderskeidelik BW, WW en CE, met ooreenstemmende beramings van 0.22, 0.36 en 0.59 vir h2 m- Genetiese korrelasies tussen direkte en mateme effekte (ram)was almal negatief en het tussen -0.32 en -0.63 gewissel. Direkte teelwaardes vir BW en WW het gedaal, terwyl die mateme teelwaardes met toenemende S-bydrae gestyg het. Koeidoeltreffendheid was nie deur 'n toename in S-bydrae beïnvloed nie. Die bevinding was dat tydens die ontleding van die eerste kruisteeltfase die teling van suiwer S aanbeveel word en dat tydens komposiete-ontwikkeling toenemende A- en H-bydraes neig om aanleiding te gee tot afnames in BW en WW (behalwe die mateme bydrae van die A vir BW en WW). Die S-bydrae se voordeel is meer in die mateme bydrae as in die direkte bydrae geleë en dui dus aan dat die S as 'n mateme grootraam lyn i.p.v. as 'n terminale bullyn gebruik moet word.

Our alarming rate of resource exploitation and its consequences on the environment is fuelling an increase in sustainable energy production around the world. Wind power appears to be a particularly promising energy source relative to its environmental footprint, with the exception of potential negative effects of wind power on birds. Varying results from impact assessments around the world indicate that knowledge of both abiotic and biotic factors, as well as bird behavior and ecology, is required to assess the cumulative impact of any given wind farm on local bird communities. This study aims to assess the cumulative impact of a proposed wind farm on a threatened seabird, the red-throated diver (Gavia stellata), at one of its breeding "hotspots" in Sweden: the Holmöarna islands. Measurements of environmental variables in lakes on Holmöarna are combined with breeding surveys from 2012 to 2015 to assess which environmental variables may be associated with lakes that red-throated divers do or do not breed in, and which variables are correlated with breeding success. These results are combined with a literature review to assess the potential negative effects of the proposed wind farm on the breeding population on Holmöarna. The results show that average breeding success over the survey period was 0.35 fledged young per pair per year. No difference was found in environmental variables between lakes that divers had or had not bred in. Lake area/perimeter ratio and distance to the sea were significantly negatively correlated with breeding success, although distance to the sea was only significant for lakes with at least one successful breeding attempt during the survey period. Based on these correlations, 33 of a total 40 breeding lakes are shown to have relatively high area/perimeter ratios and long distances to the sea, which may pre-dispose divers breeding within them to low breeding success. These lakes are, therefore, identified as being at high-to-moderate risk of increased breeding failure if breeding success is further reduced as a result of external factors, including that of any negative impacts of the proposed wind farm. 31 of the 40 breeding lakes are also within 1 km of the proposed wind turbine sites, which may render red-throated divers breeding within them vulnerable to displacement as a result of wind farm-related disturbance. The literature review highlights the mechanisms that may determine the cumulative impact of the wind farm on red-throated divers in terms of collision mortality, habitat displacement, and barriers to movement. The strong sensitivity of red-throated divers to disturbance is considered to be the most likely driver of any negative effects of the wind farm. In this context, I thus argue the need for a precautionary approach to planning wind power developments in the vicinity of breeding red-throated diver populations.

The most important income for the pig industry in Italy arises from the processing of meat in high-added-value typical products, mainly dry-cured hams having Protected Designation of Origin (PDO) label. Even through use of purebred pigs is not an exception, raw thighs are largely obtained from crossbred (CB) animals, which are slaughtered at heavy body weight (BW) (nearly 165 kg) and advanced age (270 d or more). Breeding programs of pig lines linked to dry-cured ham production should focus on enhancement of growth performance, carcass traits and qualitative and technological properties of green thighs, in order to comply the rules dictated by the disciplinary of production. Moreover, the breeding goal (aggregate genotype) must be defined at the level of the “CB slaughter animal”, so that the unfavourable effect on selection response due to genetic differences between purebreds (PB) and crossbreds, but also to environmental differences between nuclei and commercial farms, is alleviated. Given that breeding values (EBV) estimated using purebred phenotypes are often poorly related to the breeding goal defined at crossbred levels, the approach called “combined crossbred-purebred selection” is used in traditional genetic evaluation. It consists in estimation the EBV for the relevant traits using both PB and CB information. This approach is troublesome because it requires the availability of crossbred animals (half-sibs of the PB breeding candidates) which must be specifically reared as tested animals, and the phenotypic records of traits difficult and expensive to measured (as ham quality traits and curing losses). Moreover, EBV for members of a PB full-sibs family are identical when no PB individual information is available. The main aim of this thesis was to provide new knowledge about innovative traits important in heavy pig industry and to propose new statistical models and genetic evaluation procedures to enhance the prediction of breeding values for carcass traits, and qualitative and technological properties of raw thighs. The studies were carried out in collaboration with an Italian breeding company, Gorzagri s.s. (Fonzaso, Italy). It aims at producing boars (C21 line) and gilts (Goland line) used in commercial farms as sires and dams of CB pigs which are reared for production of PDO dry-cured hams. The first part of this thesis aimed to investigate the prevalence and the genetic determinism of boar taint (BT), a new trait related to both meat quality and animal welfare which is becoming increasingly important for pig industries in EU countries after the decision to ban surgical castration of piglets from 1 January 2018, and hence, the need to find alternative to reduce BT in entire male pigs. The objectives of the study were: to evaluate the prevalence of BT in intact male pigs at 160 and 220 d of age, and to estimate the genetic parameters for BT compounds at the two different ages and the genetic relationships with growth traits. Contents of androstenone (AND), skatole (SKA) and indole (IND) have been quantified by HPLC with fluorescence detection in biopsy samples of adipose tissues collected in-vivo from the neck area of 500 C21 entire male pigs at 160 and 220 d of age. In addition, for 100 of the investigated animals, BT compounds were quantified also in a sample of subcutaneous fat of raw thighs collected at slaughterhouse. Contents of BT compounds measured in intact male pigs at 220 d were higher than those found at 160 d of age, as well as the percentage of samples that exceeded the sensory thresholds discriminating tainted from untainted carcasses. Thus, the prevalence of BT is expected to be greater in mature and heavy pigs in respect to young and light pigs. The high phenotypic correlations between the contents of BT compounds measured in backfat and ham subcutaneous fat suggest that BT might be relevant also in PDO dry-cured hams. Medium-high heritabilities were found for contents of BT compounds at both ages, indicating that reduction of BT by means of genetic selection seems a valid alternative to surgical castration in pigs slaughtered at heavy BW. Genetic correlations between the contents of BT compounds measured at the two different ages were moderate to high. However, Spearman’s rank correlations revealed that the breeding candidates ranked differently when measures of BT compounds taken at the different ages are used. Finally, weak genetic correlations were found between BT compounds and growth traits, indicating that selective breeding to decrease the contents of AND, SKA and IND is expected to have trivial effects on growth performance. In the second section of this thesis the contribution of social genetic effects on variation of carcass and ham quality traits was investigated. In the current breeding program of C21 line the impact of the genetic effect of an individual on phenotypes of its pen mates (called social genetic effects or heritable social effects) is neglected. If present, social genetic effects are part of the total heritable variance and they affect the response to selection. The aims of this study were to estimate (co)variance components for body weight adjusted at 270 d (BW270), carcass and ham quality traits using direct and competitive models, and to compare the ability of such models to fit the data. The study was carried out on 9,871 CB finishing pigs raised in social groups containing from 4 to 7 individuals (6.1 pigs per group on average). Four sequential univariate animal models were compared through likelihood ratio test. REML estimates of covariance components were obtained for BW270, carcass backfat depth and lean meat (CLM), iodine number (IOD) and linoleic acid content of raw ham subcutaneous fat, subcutaneous fat depth in the proximity of semimembranosus and quadriceps femoris muscles, and linear scores for ham round shape (RS), subcutaneous fat (SF), and marbling. Model comparison based on likelihood ratio test revealed that the model accounting for heritable social effects was significantly better than the best direct model for BW270, CLM, IOD, RS, and SF. The contribution of social genetic effects to the total heritable variance was large for CLM and BW270, whereas the one for ham quality traits was lower. The correlation between direct and social additive genetic effects was positive for BW270, but it was not significantly different from zero, suggesting independence between direct and social genetic effects for this trait. In contrast, a negative genetic covariance between direct and associative components was found for CLM, IOD, RS, and SF, which reduced the total heritable variance exploitable for genetic selection. The results obtained in this study suggest that social genetic effects affect variation in traits relevant for heavy pigs used in dry-cured hams manufacturing and, hence, the procedures for estimation of breeding values should take heritable social effects into account. The third part of this thesis aimed to investigate new methods including genomic information in order to enhance the EBV prediction for traits related to carcass, ham quality and manufacturing of dry-cured hams. Genomic selection (GS) approach might overcome some of the drawbacks of current procedures for genetic evaluation of C21 line based on sib-testing. The objective of the first study regarding GS was to develop and to investigate GS procedures based on single step BLUP (SSBLUP) methodology for genomic evaluation of PB breeding candidates of C21 boar line for traits relevant for dry-cured ham production. Observations on BW270, carcass and ham quality traits were recorded from 11,488 CB finishing pigs. In addition, for 1,878 of the investigated animals, phenotypes for weight losses occurring during salting, resting and curing production stages were available. To constitute the reference population, 1,088 CB pigs, 136 nucleus boars (C21_NB: sires of CB tested pigs) and 500 C21 half-sibs of CB animals (C21_HS: half-sibs of CB tested animals) were genotyped for 8,826 single nucleotide polymorphisms using GGP Porcine LD Chip. Traditional evaluation was performed using BLUP methodology, whereas genomic evaluation was carried out using SSBLUP method which combine pedigree and genomic information in order to estimate genomic breeding values (GEBV) for both genotyped and ungenotyped animals. Pearson’s correlation coefficients between EBV and GEBV (r_(EBV,GEBV)) were calculated in order to compare traditional and genomic evaluation. In addition, the 500 C21_HS with genotypic information were used to validate the prediction equation. High r_(EBV,GEBV) were observed for all the investigated traits for both CB animals, C21_NB, suggesting that genetic merit estimated using GS was consistent with breeding values prediction from traditional evaluation. Positive and moderate to high r_(EBV,GEBV) were observed for C21_HS used in validation population. Differences in ranks of breeding candidates were found when they were based on traditional EBV or GEBV. In contrast to EBV, GEBV differed for members of a PB full-sibs family when they had genomic information. Thus, GS allows to choose the best animals based on “individual” genetic merit rather than “family” merit, increasing the accuracy of selection and reducing the rate of inbreeding. In addition, GS procedures might simplify genetic evaluation of PB breeding candidates of C21 boar line for traits difficult to measure. As found in the second part of this thesis, competitive models provided a better fit than classical direct model for BW270, CLM, IOD, RS and SF. Hence, for these traits, traditional genetic evaluation accounting for heritable social effects was compared to SSBLUP analysis performed using a competitive model. The dataset used in this study was the same described above. For animals in validation population, positive and moderate to high Spearman’s correlation coefficients between direct EBV and direct GEBV were found for all the investigated traits, as well as between total breeding values and total genomic breeding values (TGBV). Hence, differences in ranks of breeding candidates were observed even when social genetic effects were included in the genomic evaluation. In fact, GS procedures accounting for heritable social effects allow to obtain individual TGBV rather than “family” TBV, increasing the benefit of GS for genetic evaluation of PB boar lines linked to dry-cured ham production.
I profitti più rilevanti per l’industria suinicola italiana derivano dalla trasformazione della carne in prodotti tipici di alto valore economico, principalmente prosciutti crudi con Denominazione di Origine protetta (DOP). Le cosce fresche destinate alla produzione dei prodotti DOP derivano principalmente da soggetti ibridi che vengono macellati a pesi elevati (circa 165 kg) e ad età avanzate (almeno 270 giorni). I programmi di selezione delle linee suine destinate alla produzione dei prosciutti crudi dovrebbero focalizzarsi sul miglioramento delle prestazioni di crescita, della qualità della carcassa e delle caratteristiche qualitative e tecnologiche delle cosce fresche, cosicché i requisiti dettati dai disciplinari di produzione siano soddisfatti. In questo scenario gli obiettivi di selezione devono essere definiti a livello di soggetto ibrido, piuttosto che a livello di linea pura. I valori genetici (breeding values, EBV) stimati utilizzando le informazioni fenotipiche dei soggetti di linea pura sono poco correlati con gli obiettivi di selezione definiti al livello dei soggetti ibridi. Per questo la valutazione genetica dei candidati riproduttori di linea pura attualmente avviene attraverso un approccio che combina informazioni derivanti sia da soggetti puri che da soggetti ibridi. Questo approccio presenta alcune criticità dovute alla necessità di allevare appositamente soggetti ibridi (mezzi fratelli dei candidati riproduttori di linea pura) per ottenere i rilievi fenotipici per caratteristiche che alcune volte sono difficili da misurare (come i caratteri di qualità della coscia o i cali di stagionatura). Inoltre, quando nella valutazione genetica non sono incluse informazioni fenotipiche rilevate sugli animali di linea pura, i EBV per i candidati riproduttori che appartengono alla stessa famiglia di fratelli pieni sono identici. L’obiettivo principale della tesi è stato quello di fornire nuove conoscenze su caratteri innovativi per l’industria del suino pesante e di proporre nuovi modelli statistici e procedure di valutazione genetica per migliorare la predizione dei EBV per caratteri legati alla qualità della carcassa e delle cosce fresche destinate alla produzione dei prosciutti crudi DOP. Gli studi qui presentati sono stati condotti in collaborazione con un’azienda suinicola italiana, Gorzagri s.s (Fonzaso, Italia). Essa ha come obiettivo la produzione di verri (linea C21) e scrofe (linea Goland) usati negli allevamenti commerciali come padri e madri di soggetti ibridi destinati alla produzione dei prodotti DOP. La prima parte della tesi si proponeva di studiare l’incidenza e il determinismo genetico dell’odore di verro, un nuovo carattere associato sia alla qualità della carne che al benessere animale, il quale sta diventando sempre più rilevante per l’industria suinicola italiana ed europea dopo la decisione di abbandonare la castrazione chirurgica dei suinetti maschi a partire dal 1 gennaio 2018. Questo impone la necessità di trovare valide alternative a questa pratica per ridurre l’odore di verro nei suini maschi interi. Allo scopo di indagare la possibilità di sfruttare la selezione genetica per limitare l’odore di verro nel suino pesante, gli obiettivi dello studio sono stati: valutare la prevalenza dell’odore di verro in suini maschi interi di 160 e 220 giorni d’età e stimare i parametri genetici per i composti responsabili del problema alle due diverse età nonchè le relazioni genetiche che intercorrono tra questi e i caratteri legati all’accrescimento. I contenuti di androstenone (AND), scatolo (SCA) e indolo (IND) sono stati quantificati tramite cromatografia liquida ad alta prestazione in microcampioni di tessuto adiposo prelevati in-vivo dalla regione del collo di 500 suini maschi interi della linea C21 al raggiungimento dell’età di 160 e 220 giorni. Inoltre, per 100 di essi, i composti sono stati quantificati anche in un campione di grasso di copertura della coscia prelevato in sede di macellazione. Le concentrazioni dei tre composti misurati nel grasso di animali di 220 giorni sono risultati superiori a quelli riscontrati a 160 giorni di età, così come la percentuale di campioni che superano i limiti di accettabilità utilizzati per discriminare le carcasse affette o meno dall’odore di verro. Questo suggerisce che l’incidenza del problema dell’odore di verro è maggiore nei suini più pesanti e maturi da un punto di vista sessuale. Inoltre, un’elevata correlazione è stata riscontrata tra il contenuto di AND, SCA e IND nel grasso dorsale e nel grasso di copertura delle cosce, suggerendo che il problema può essere rilevante anche nei prosciutti crudi DOP. I composti responsabili dell’odore di verro hanno mostrato un’elevata ereditabilità ad entrambe le età, confermando che la selezione genetica potrebbe essere una valida soluzione per ridurre l’odore di verro anche in suini macellati a pesi elevati. Le correlazioni genetiche tra AND, SCA e IND misurati alle due diverse età sono risultate di grado moderato o elevato. Tuttavia, sono state riscontrate delle differenze nelle classifiche dei candidati riproduttori quando i fenotipi misurati alle due diverse età sono stati usati per la stima dei EBV. Infine, le correlazioni genetiche tra AND, SCA e IND e caratteri legati all’accrescimento sono risultate modeste, suggerendo che la riduzione della concentrazione di questi composti nel tessuto adiposo tramite selezione genetica non dovrebbe influenzare le prestazioni di crescita in suini non castrati. Nella seconda parte di questa tesi è stato esaminato in contributo degli effetti sociali sulla variabilità di caratteri legati alla qualità della carcassa e della coscia in suini pesanti. Le attuali procedure di valutazione genetica della linea C21 non tengono in considerazione l’influenza che il genotipo di un animale ha sul fenotipo dei suoi compagni di gruppo (effetto sociale). Se presenti, gli effetti sociali contribuiscono alla varianza ereditabile e quindi possono influenzare la risposta alla selezione. Lo studio si è quindi proposto di stimare le componenti di varianza per il peso a 270 giorni di età (PESO270), caratteri di qualità della carcassa e della coscia utilizzando modelli genetici “classici” e modelli competitive (che includono gli effetti sociali), nonché determinare la bontà dell’adattamento ai dati di questi modelli. Lo studio è stato condotto su 9,871 suini ibridi Goland allevati in gruppi contenenti da 4 a 7 individui, con dimensione media del gruppo pari a 6.1 suini. Quindi, quattro modelli sequenziali sono stati utilizzati per la stima delle componenti di varianza. Il confronto dei modelli ha rivelato che il modello competitive mostra un miglior adattamento ai dati rispetto ad un modello che considera solo gli effetti genetici additivi per il PESO270, la percentuale di carne magra in carcassa (CM), il numero di iodio, la globosità e lo spessore del grasso sottocutaneo misurati sulla coscia. Gli effetti sociali contribuiscono in modo considerevole alla varianza ereditabile per il PESO270 e CM, mentre hanno un effetto meno rilevante per gli altri caratteri esaminati. La correlazione tra la componente genetica additiva e quella sociale è risultata negativa per i caratteri legati alla qualità della carcassa e della coscia, causando una diminuzione della varianza ereditabile sfruttabile per la selezione di questi caratteri. In conclusione, lo studio ha dimostrato che gli effetti sociali contribuiscono alla variabilità di caratteri rilevanti nel suino pesante destinato alla produzione dei prosciutti crudi DOP e, quindi, le attuali procedure per la valutazione genetica della linea C21 dovrebbero includere anche la componente sociale. La terza parti della tesi ha riguardato lo studio di nuove procedure di valutazione genetica basate sulla selezione genomica (SG). L’obiettivo è quello di migliorare la predizione dei EBV per caratteri importanti nel suino pesante superando alcune delle criticità dell’attuale sistema di valutazione genetica della linea C21 basato su un programma di sib-testing. In un primo lavoro, sono state studiate procedure di SG basate sulla metodologia single-step BLUP (SSBLUP). Le informazioni fenotipiche per caratteri riguardanti la qualità della carcassa e della coscia sono state registrate in 11,488 suini ibridi Goland. Per 1,878 animali sono stati inoltre rilevati i cali di peso della coscia durante le diverse fasi di trasformazione in prosciutto crudo. Allo scopo di costituire la popolazione di riferimento per lo sviluppo dell’equazione di predizione dei breeding values genomici (GEBV), 1,088 soggetti ibridi, 136 verri nucleo di linea C21 (C21_VN) e 500 soggetti C21 mezzi fratelli degli animali ibridi (C21_MF) sono stati genotipizzati per 8,826 polimorfismi a singolo nucleotide utilizzando il DNA chip GGP Porcine LD Chip. La valutazione genetica tradizionale è stata condotta sfruttando la metodologia BLUP, mentre la valutazione genomica si è basata su un approccio SSBLUP. L’equazione di predizione dei GEBV è stata validata utilizzando i 500 C21_MF con genotipo come popolazione di validazione. La valutazione genetica tradizionale e quella genomica sono state confrontate tra loro attraverso la correlazione tra EBV e GEBV (r_(EBV,GEBV)). Elevati coefficienti di correlazione tra EBV e GEBV sono stati osservati sia per i soggetti ibridi genotipizzati che per gli individui C21_VN, suggerendo che le stime dei GEBV sono simili a stime accurate dei EBV ottenute con metodi tradizionali. Per quanto concerne i soggetti inclusi nella popolazione di validazione, r_(EBV,GEBV) sono risultate di entità minore rispetto ai due gruppi considerati in precedenza. Differenze nelle classifiche dei candidati riproduttori sono state osservate quando esse erano basate sui EBV piuttosto che sui GEBV. Tali differenze sono attribuibili all’abilità della metodologia SSBLUP di stimare GEBV individuali, anziché EBV identici per soggetti che appartengono alla stessa famiglia di fratelli pieni (quando essi hanno informazione genomica). Quindi l’utilizzo di un approccio di SG permette di scegliere i soggetti migliori in base a meriti genetici individuali piuttosto che “familiari”, limitando il tasso di consanguineità e aumentando l’accuratezza della selezione. Inoltre, i risultati ottenuti rivelano che l’implementazione di procedure di SG nel programma di selezione della linea C21 consentirebbero di introdurre tra gli obiettivi di selezione anche caratteri di difficile misurazione. Come descritto in precedenza, gli effetti sociali contribuiscono alla variabilità di caratteri rilevanti per il suino pesante e che modelli competitive forniscono un miglior adattamento ai dati per i caratteri PESO270, CM, il numero di iodio, la globosità e lo spessore del grasso sottocutaneo misurati sulla coscia. Quindi, per questi caratteri, sono state analizzate procedure di SG basate sulla metodologia SSBLUP che consideravano, oltre agli effetti genetici diretti, anche gli effetti sociali. Le informazioni fenotipiche e genomiche utilizzate sono le medesime descritte per il precedente studio. Differenze nelle classifiche degli animali inclusi nella popolazione di validazione sono state riscontrate sia quando esse erano basate su EBV e GEBV riferiti alla sola componente genetica diretta, che quando sono stati utilizzati i valori genetici e genomici totali. Quindi l’implementazione procedure di SG nel programma di selezione della linea C21 che utilizzano modelli competitive consentirebbero di sfruttare i vantaggi della SG già descritti in precedenza e contemporaneamente stimare più correttamente la varianza ereditabile totale considerando anche la componente associativa.

A simulation approach was used to determine the effects of multitrait selection on the correlations of sire direct and maternal predicted breeding values across environments. True and predicted direct and maternal breeding values (BV) of sires were simulated for sires evaluated independently in two different environments. Prediction error variances and covariances among direct and maternal BV within environments were required for the simulation. To obtain the necessary input parameters, a variety of MME coefficient matrices were created and inverted to inspect relationship among accuracies and correlations of prediction errors in sire evaluation models. An empirical prediction equation to predict the necessary prediction error covariances was obtained. Divergent, directional and random multitrait selection was then practiced using direct and maternal predicted BV as selection criteria. Samples of 40 sires were randomly obtained from each selected population. Observed correlations between direct and maternal predicted BV across environments were compared to expectations derived from univariate distribution theory. Selection definitely affected the expectations. However, the adjustment developed from univariate theory appeared to accommodate the effect of selection in these expectations.
Ph. D.

Neuropeptides are well known to govern numerous biological functions and are found in all phyla studied to date. Probably the best known neuroendocrine system is the hypophyseal-portal system found in vertebrates, and one of the functions of this system is to mediate reproduction. Mammalian reproduction is controlled by a hormonal cascade which begins in distinct brain regions, namely the hypothalamus and the pituitary gland. Gonadotropin-releasing hormone (GnRH) is a neuropeptide typically produced in the hypothalamus. It is the key neuropeptide for initiating this cascade, and without it, reproduction cannot occur. Naked mole rats (Heterocephalus glaber) have a rigid social hierarchy. The "queen" is the most dominant female and is the only female who breeds. All aspects of reproduction are suppressed in other females in the colony: these "subordinates" are in a prepuberty-like state as they do not ovulate or display breeding behaviours. They are, however, not infertile, and are capable of rising to the breeding position. Since GnRH is the "master hormone" of reproduction, this study investigates its role in the socially-induced suppression of reproduction in female H. glaber. Brains of breeding (n = 7) and non-breeding (n = 5) female naked mole rats were compared to determine any differences in brain size, particularly in regions related to GnRH production. Noteworthy morphological and physiological transformations accompany the change from subordinate to dominant social status, including a significant increase in body length (Mann Whitney U test; p = 0.005, U = 0.000), body mass (Mann Whitney U test; p = 0.009, 1.000) and pituitary width and length (Mann Whitney U test; p = 0.028, U = 0.500 and p = 0.018, U = 0.000, respectively). Since little is known about the GnRH system in H. glaber, this study used immunocytochemistry to identify the distribution and abundance of GnRH neurons in the brains of both breeding and non-breeding females. GnRH neurons were found in the median eminence of the hypothalamus and in the anterior pituitary of both queens and subordinates, however in the brain of queen (n = 7) naked mole rats, there is a significantly larger area of immunoreactivity in comparison to the subordinate (n = 5) brain tissue (Mann Whitney U = 4.000, p = 0.030). This suggests that, in , subordinates, GnRH is inhibited at the level of production. The amino acid structure of the form of GnRH found in the brain of the naked mole rat is currently unknown, therefore a pilot study was carried out, using synthetic mammalian GnRH (mGnRH), mouse brain tissue and naked mole rat pituitaries and hypothalami, to examine and modify (where necessary) the methodologies used for neuropeptide extraction, purification and identification. A limited number of naked mole rats were available as source tissue (n = 4), therefore this study also tested whether it is possible to extract and purify an unknown neuropeptide from only a few mammalian samples. Training for reverse-phase liquid chromatography (RP-HPLC) was achieved by practicing the necessary methods with crude extracts prepared from stick insect (Carausius morosus) corpora cardiaca, which also served to compare vertebrate and invertebrate neuroendocrine systems. Synthetic mGnRH was used to demonstrate repeatability of the protocol and to set up suitable conditions for elution of mGnRH: mGnRH elutes at â 12 min when a solvent gradient of 32 % - 47 % B is applied. Synthetic mGnRH was also used to establish the amount of peptide required for accurate identification of GnRH by antigenicity tests (ELISA) and mass spectrometry. However, when extracts of mouse or naked mole rat brain matter were applied to this system, purification of GnRH was unconvincing as either there was insufficient material, or, some endogenous factor was masking the GnRH. Future studies would benefit from using molecular techniques as they require smaller amounts of source tissue. Alternatively, a larger amount of source tissue would be necessary in order to proceed with biochemical studies. While the impaired production of GnRH in subordinate naked mole rats seems to be linked to their prepuberty like state, it is unlikely that GnRH is the sole factor involved. Many other hormones (such as kisspeptin, gonadotropin-inhibiting hormone and neuropeptide Y) may influence GnRH and sexual maturity, and future studies would benefit from a multi-layered approach to investigate suppression of reproduction in naked mole rats.

Whenever multiple individuals contribute to the care of offspring, the optimum level of investment for each carer depends on the behaviour of the others. Previous theoretical and empirical work has largely focused on carer contributions within a single stage of a breeding attempt, neglecting the potential for investment during earlier stages to influence later care decisions. Typically, mothers have much greater control than other carers over the number and quality of offspring, and hence by altering her investment during offspring production a mother can adaptively adjust offspring phenotype to match or exploit the predicted care paradigm. In this dissertation, I use theoretical, empirical and comparative methods to investigate the influence of maternal tactics on investment rules in cooperative breeding systems, where ‘helpers’ care in addition to parents. In three chapters I model maternal control of offspring quality and offspring number across a cooperative breeding attempt, and investigate how the costliness of different reproductive stages, the kin-structure of the care group, and the consequences of offspring early-life condition influence the investment rules of carers. During offspring rearing, fair division of labour within a cooperative group can theoretically be resolved using simple turn-taking rules, leading to efficient outcomes for all carers. To test whether such a rule is employed in nature, a later chapter analyses empirical provisioning data from the chestnut-crowned babbler (Pomatostomus ruficeps), a cooperatively breeding bird endemic to the Australian outback. I use a Markov chain Monte Carlo approach to determine whether individuals alter their provisioning rate when other carers visit the nest, and identify both ‘passive’ and ‘active’ turn-taking behaviour. Finally, I present a comparative analysis of studies on provisioning rules in cooperatively breeding birds, and investigate whether the level of investment mothers must contribute to offspring influences the later care paradigm observed. My results indicate that maternal costs contribute to variation in both breeding group size and female provisioning behaviour. I conclude that maternal investment tactics are an underappreciated influence on carer investment rules in both the theoretical and empirical literature, and that incorporating them is crucial to understanding variation in cooperative care behaviour in nature.

Ruddy Ducks in the Chilcotin parklands of British Columbia nest in late June, July and early August, later than most other waterfowl species breeding in southwestern British Columbia, Canada. This thesis considers factors that may affect the timing of breeding in Ruddy Ducks by comparing Ruddy Ducks to Barrow's Goldeneye and Bufflehead (species that breed early but do not renest) and to American Coot (a species that breeds early and is able to renest). These factors include predation, flooding and desertion of nests, feeding behavior of ducklings, abundance of food, availability of green vegetation and fluctuations in temperature. Possible advantages of late breeding include reduced nest predation and higher ambient temperature during incubation. Longer dive durations and more frequent feeding and resting by Ruddy ducklings may enable ducklings to maximize energy for growth. Reduced nest flooding late in the season, dependence on green vegetation for nesting and greater abundance of food for young in summer were not demonstrated by this study. Therefore, these factors apparently do not explain the timing of breeding in Ruddy Ducks in southwestern British Columbia. Despite insufficient time to renest and shorter time for ducklings to mature before ponds freeze, the average number of 2B age class young produced per pair of Ruddy Ducks was similar to that of American Coots. Forty percent of nesting Ruddy females did not hatch any young, whereas almost all nesting Coot females successfully hatched young; however, survival of Ruddy ducklings to 2B age class (four weeks old) was higher than that of American Coots, Barrow's Goldeneye and Bufflehead.
Science, Faculty of
Zoology, Department of
Graduate