The central goal of human genetics is to understand genetic differences both within and between populations and how these differences contribute to phenotypic variation. Recent advances in genotyping technologies and statistical methodology mean that we can now examine population differences at high genetic resolution, and attempt to find common variants that underlie variation in complex traits in the population. In this thesis, differences in maternal genetic ancestry in Australia were examined and a number of genetic association studies were undertaken in an attempt to map genetic variants that underlie complex traits. Abstract Before presenting the results from the five main genetic analyses, an overview is given of the history of gene-mapping in humans, the challenges this has presented, and the major discoveries from both empirical and theoretical studies that have advanced the field of human genetics to the point where hypothesis-free association testing of common variants with complex traits is now possible. The reasons why mitochondrial DNA has proved so useful in examining the history of populations, and the major findings from the field of mitochondrial population genetics are summarised. In addition, some of the major evidence of a role for mitochondrial variants in complex trait variation is presented. For the first main paper, data from 69 mitochondrial variants that tag the majority of common mitochondrial SNPs in European populations was used to test whether there is evidence for population stratification (i.e. the presence of more than one randomly mating population) in the maternal genetic line of modern Australians. By combining the genetic data with self-reported maternal ancestry data, it was shown that there are significant differences in the patterns of mitochondrial variation between groups of individuals whose maternal ancestors came from different areas of the world. Specifically, it was shown that there are significant differences between groups from different regions of Europe, with those from Eastern Europe showing large differences in SNP and haplogroup frequencies compared to the other groups. A test for assortative mating was performed by comparing whether mates in our sample shared more mitochondrial variants in common when compared to randomly drawn pairs from the population. No evidence of increased sharing was found. The second study involved testing whether common mitochondrial variants are associated with a number of physiological and biochemical traits, the majority of which are risk factors for the metabolic syndrome and type 2 diabetes. Phenotypic and genotypic data was available for just over 2,000 adolescent twins measured at three different timepoints. This is the first known mitochondrial association study to use family data, and a methodology based on a linear model was presented for performing such an association. In spite of having power to detect variants of modest effect, only viii one significant association was found between mt14365 and triacyglycerol levels in twins measured at age 12. This association was not replicated across the other age groups. The third study used the methodology developed for family-based mitochondrial association studies to test for association between mitochondrial variants and a battery of cognitive tests in twins aged 16. A previous study with a small sample size had shown an association between mitochondria and IQ, but this had never been replicated or followed-up. A total of 1,385 individuals from 665 families were included, but no statistically significant associations were found. The most strongly associated SNP was found in a gene in which variants have been shown to influence cognition in mice with a homogeneous nuclear genetic background. For the fourth study, a genome-wide association analysis was carried out of 6 self-reported traits related to the menstrual cycle. Sample sizes ranged from 468 for age at menopause to 5,743 for age at menarche. No SNPs were found to be associated at a genome-wide significant level, however, the results from previous association analyses of age at menarche and age at menopause were replicated. A number of regions for each trait that show modest evidence of association have been identified, and these should be targeted for replication in another sample. In addition, a number of genes that show strong evidence for association with each trait were identified and using a multivariate approach, a SNP in the RNA polymerase III subunit B gene was shown to potentially have a pleiotropic effect on age at menarche and duration of menses. In the final study, a genome-wide association study data for self-reported caffeine consumption and caffeine-related sleep disturbance was performed. A number of loci that potentially influence each trait were identified. The association data was combined with gene expression data from three cell types that had been treated with caffeine. A gene-based test was performed to test whether genes that were found to be consistently up- or down-regulated by caffeine treatment show increased evidence of association. There was no evidence of increased association signals in these genes. A number of the caffeine-regulated genes show strong evidence for overall association and represent good candidate genes for targeted replication in a larger sample. Finally, a synthesis of the main results of each study is presented including potential limitations of this research. This discussion includes a critical assessment of the current findings in both mitochondrial genetics and genome-wide association studies, and potential future directions in the field of gene-mapping in humans.

Many species have suffered severe range contractions as a result of human impacts, and require careful management if they are to persist. An understanding of the ecology, population structure and mating system is important for the conservation of these endangered species. Translocation has become a widely used tool in the conservation of threatened species; however, without proper planning and monitoring, many programmes end in failure. The bridled nailtail wallaby is one of the most endangered macropods in Australia, having suffered an extensive range contraction from the semi-arid region of eastern Australia to a single remnant population of ~ 500 animals at Taunton National Park in Queensland. In 1996, a translocated population of bridled nailtail wallabies was established at Idalia National Park, on the western edge of the former range of this species. The aims of this study were to: 1) determine the factors underlying variation in reproductive success among animals released at Idalia; 2) investigate the effects of a range decline on the genetic variation and population structure of the remnant population at Taunton; 3) assess the impact of captive breeding and translocation on the genetic diversity and structure of the established population at Idalia; and 4) investigate male and female mating strategies in this species. Chapter two investigated reproductive success among males released at Idalia National Park. The bridled nailtail wallaby is a sexually dimorphic, polygynous species and there is a large amount of variation in male reproductive success. Animals of different origin were released, including animals bred in captivity off the park, animals bred on-site in enclosures, and wild-caught animals from the remnant population that were moved directly to Idalia. There was significant variation in reproductive success among males released, but the origin of those animals did not explain this variation. Instead, large males were the most reproductively successful regardless of origin. Survival probability and release location were also important factors. This study highlighted the importance of considering mating system when choosing animals for translocation and suggests that, for polygynous species, a greater proportion of females and males of high breeding potential should be released. In Chapter three I investigated the genetic diversity and fine-scale genetic structure of the remnant population at Taunton. This last remaining population has been isolated for at least 60 years, corresponding to 30 generations for this species. Animals are patchily distributed in assemblages of different size that cover ~ 10% of suitable habitat on the park. Genetic diversity was surprisingly high within the population remnant and this species showed one of the highest levels of heterozygosity and allelic diversity of any macropod. The three sub-populations of animals sampled over 10 km were significantly differentiated, and fine-scale spatial genetic structure was also observed within a continuous sub-population of animals covering just 750 ha. Females were more related to each other than expected from random, whereas males were less related to each other than expected. Fine-scale genetic structure was observed among females but not males, providing evidence for female philopatry and male-biased dispersal. I suggest that fine-scale population structure and restricted gene flow among females but not males may maintain genetic diversity in this remnant population. Chapter four assessed the effect of translocation of animals of different origin on genetic diversity in bridled nailtail wallabies. Both wild-caught and captive-bred animals were initially released, but subsequent releases consisted of captive-bred animals only. In this study, I compared genetic diversity of released animals to animals sampled in the remnant population. Heterozygosity did not differ between the remnant and translocated population, however allelic diversity was significantly reduced among all groups released. Animals bred in captivity were significantly differentiated from the source population, whereas animals moved directly from Taunton were not. Releasing more captive-bred animals into the population after the initial release resulted in a decline in overall heterozygosity and allelic diversity. This study highlights the importance of sourcing animals directly from remnant populations in order to maintain genetic diversity and minimize genetic drift between source and recipient populations. The bridled nailtail wallaby has a polygynous mating system and reproductive success is skewed toward large males. However unlike most polygynous, sexually dimorphic macropods, the bridled nailtail wallaby is highly solitary; animals only associate to breed and males do not form stable dominance hierarchies. In Chapter five I investigated behavioural strategies used by males to secure matings, and mate choice among females. I found that males of different size adopted different mating strategies. Large males spent more time guarding females against other males and maintaining contact with them, whereas smaller males spent less time with guarded females in order to search for other females in oestrus. Females also preferred larger males and were more likely to engage in mate chases if there was a large number of males within the group.

Licentiatavhandling (sammanfattning) Alnarp : Sveriges lantbruksuniversitet. / Härtill 2 uppsatser.

Despite growing in numbers very quickly in the last half century, interracial marriage remains a disproportionately small segment of all marriages. Much research has been conducted investigating reasons for participation in interracial relationships, and the forces which impede those relationships. Using longitudinal data from the National Longitudinal Study of Adolescent Health (Add Health), I investigated several theories which had previously been researched using data of inferior quality, or only in the context of marriage relationships. I found that macrostructural and contact theories of race relations are supported strongly, and that multiracial identity has a very strong positive effect on the log odds of participation in an interracial relationship. More research is necessary to gain a full sociological understanding of interracial relationship participation as adolescents age and become young adults.

abstract: The current research seeks to examine whether individuals display or downplay intelligence in various mating contexts. I hypothesized that both men and women should display fluid intelligence when attempting to attract a potential long-term partner, and that only men should display fluid intelligence when attempting to attract a potential short-term partner. Contrary to predictions, I find that men perform worse at a fluid intelligence test when motivated to attract a long-term partner. With respect to crystallized intelligence, I predicted that both men and women should display crystallized intelligence when attempting to attract a potential long-term partner, but women should downplay crystallized intelligence when attempting to attract a potential short-term partner. However, there were no effects of mating contexts on displays of crystallized intelligence. / Dissertation/Thesis / M.A. Psychology 2013

Mionectes oleagineus (Aves, Tyrannidae) is a small, sexually monomorphic, lek breeding bird. The behaviour and mating system of this species were studied on Costa Rica's Osa Peninsula over two years. In this thesis I ask three questions: 1) What kind of social organization does M. oleagineus exhibit? 2) Does habitat influence male display dispersion? and 3) What is the function of song in attracting mates and in male-male interactions? In Chapter 2, I describe M. oleagineus' social organization. There were three categories of males: territory owners, satellites and floaters. The latter 2 categories were non-territorial and represented half of the male population. I describe interactions between displaying males and visitors to their territories, including courtship display and aggressive interactions between males. Male display dispersion was highly variable in the study area, including classical leks, in which territories shared contiguous boundaries, an exploded lek, where the territories did not share boundaries, and solitary display territories. In Chapter 3, I test the hypothesis that the number of males that can settle in an area, and their subsequent display dispersion, is determined by the availability and dispersion of suitable habitat. Discriminant function analysis of measures of vegetation structure from both territories and non-territory sample plots showed that territory habitat could be distinguished from non-territory habitat. Eleven percent of the sample plots were described as suitable habitat in the analysis. Given that half the male population is non-territorial, the existence of unoccupied, suitable habitat makes it unlikely that habitat availability determines the number of males settling, or their display dispersion. The major occupation of males on their display territories is singing. In Chapter 4, I investigate the function of song for M. oleagineus using behavioural observation and an experiment involving temporary muting. Males which sang at higher rates received more visitors of both sexes. The territories of most muted territorial males were rapidly usurped by other males. Two of the muted males regained their territories upon regaining the ability to sing. This study is the first to directly demonstrate a key role for song in male-male interactions on leks. It also provides evidence that females use song in mate assessment. / Science, Faculty of / Zoology, Department of / Graduate

Juvenile hormone (JH) is the central hormonal regulator of life-history trade-offs in many insects. In Aedes aegypti, JH regulates reproductive development after emergence. Little is known about JH’s physiological functions after reproductive development is complete or JH’s role in mediating life-history trade-offs. By examining the effect of hormones, nutrition, and mating on ovarian physiology during the previtellogenic resting stage, critical roles were determined for these factors in mediating life-history trade-offs and reproductive output. The extent of follicular resorption during the previtellogenic resting stage is dependent on nutritional quality. Feeding females a low quality diet during the resting stage causes the rate of follicular resorption to increase and reproductive output to decrease. Conversely, feeding females a high quality diet causes resorption to remain low. The extent of resorption can be increased by separating the ovaries from a source of JH or decreased by exogenous application of methoprene. Active caspases were localized to resorbing follicles indicating that an apoptosis-like mechanism participates in follicular resorption. Accumulations of neutral lipids and the accumulation of mRNA’s integral to endocytosis and oocyte development such as the vitellogenin receptor (AaVgR), lipophorin receptor (AaLpRov), heavy-chain clathrin (AaCHC), and ribosomal protein L32 (rpL32) were also examined under various nutritional and hormonal conditions. The abundance of mRNA's and neutral lipid content increased within the previtellogenic ovary as mosquitoes were offered increasing sucrose concentrations or were treated with methoprene. These same nutritional and hormonal manipulations altered the extent of resorption after a blood meal indicating that the fate of follicles and overall fecundity depends, in part, on nutritional and hormonal status during the previtellogenic resting stage. Mating female mosquitoes also altered follicle quality and resorption similarly to nutrition or hormonal application and demonstrates that male accessory gland substances such as JH III passed to the female during copulation have a strong effect on ovarian physiology during the previtellogenic resting stage and can influence reproductive output. Taken together these results demonstrate that the previtellogenic resting stage is not an inactive period but is instead a period marked by extensive life-history and fitness trade-offs in response to nutrition, hormones and mating stimuli.

Reproductive isolation is an essential stage in speciation. In Ascomycetes, the ubiquitous distribution of many species suggests that sympatric speciation through assertive mating should be an important factor. The MAT locus and the pheromone/receptor system could both potentially contribute to the development of such sexual isolation. Alterations at the MAT loci could lead to distinct reproductive habits or a change in mating system, both of which can reduce gene-flow between species. However, if deliberate pre-mating sexual preferences exist, they are more likely to be determined by the pheromone/receptor system. This study of Fusarium reproductive genes, and comparisons with other Ascomycetes, has yielded numerous interesting findings regarding the evolution of these mate-recognition mechanisms and the implications thereof. The G. fujikuroi and F. graminearum species complexes have offered an interesting comparison between heterothallic and homothallic MAT locus evolution. The value of comparative sequence analysis has been demonstrated in the discovery of a previously unknown gene, MAT1-2-3, which may be specific to members of the Order Hypocreales. While all MAT genes share similar regulatory elements, this is the first report of evidence that a transition to homothallism can be accompanied by the recruitment of distinct elements that could facilitate alternate expression of MAT genes. The MAT genes are also highly divergent between Fusarium spp., largely due to relaxed selective constraint, particularly in homothallic species. However, inter-specific gene-flow could curb MAT gene divergence among homothallic species. Despite strong reproductive barriers in the G. fujikuroi complex, the F. sacchari MAT1-1 sequence appears to have been acquired through lateral transfer from a distant relative. Analytical analysis of the MAT locus novelties reported here, including the new MAT gene, will be necessary to determine their biological significance. To investigate the extent of pheromone diversity in the Ascomycetes, and to gain clues as to its biological importance, pheromone peptides from seventy ascomycete species were compared. A number of reproductively incompatible species, such as those in the G. fujikuroi complex, share identical pheromones; which implies that another mechanism must be responsible for the observed reproductive barriers. However, on the whole, pheromones are highly divergent among species. Both adaptive and non-adaptive evolution could have contributed to this pattern. In fact the structure of the á-class pheromone precursor gene, which consists of multiple repeats of the pheromone module, could facilitate rapid diversification through “birth-and-death” evolution. Within species, selection maintains pheromone peptides, implying that much of the inter-specific variation is functionally relevant. This further suggests that pheromone evolution could contribute to the generation of reproductive isolation between species. The most general trend in the findings of this study is that ascomycete reproductive genes are highly divergent. This is in agreement with findings in other Kingdoms. A number of evolutionary forces are probably involved but weaker selective constraint, resulting from the fact that reproduction is not essential in these fungi, appears to be a common factor. This reproductive gene variability could be directly linked to speciation and, therefore, the great diversity in Ascomycetes. Additional information on the appendices is available on a CD, stored at the Merensky Library on Level 3 / Dissertation (MSc)--University of Pretoria, 2011. / Genetics / Unrestricted

Patterns of sperm usage in multiply-mated females have profound fitness consequences for males, and create strong selective pressure on male behavior. In the cooperative theridiid spider Anelosimus studiosus Hentz 1850 adult males are tolerated in females' webs, and females have been observed to mate multiply with different males. In this experiment, virgin females were mated with two different males on consecutive days under controlled conditions to determine paternity patterns and behavioral responses of males to non-virgin females. The paternity of broods was analyzed using randomly amplified polymorphic DNA (RAPDs). Fifteen broods were analyzed and complete first male sperm precedence was found. Mating behavior differed between first and second males with the first males attempting fewer intromissions, but having a longer total time of intromission. This suggests that the second males are either prevented from normal copulation, or are reacting to the different condition of the females. The sperm precedence pattern is discussed with respect to its ramifications for male behavior, juvenile inclusive fitness, and the evolution of cooperative behavior.

European whitefish (Coregonus lavaretus) forms reproductively isolated sub-populations with different body sizes in the lakes where northern pike (Esox lucius) exists. It has been hypothesized that the initial reproductive isolation between ecotypes arises through size-assortative mate choice or because small and large individuals arrive to the spawning grounds at different times. To test these hypotheses, I caught and measured both breeding whitefish pairs and singular whitefish on the spawning grounds over the spawning season. There was no correlation between the lengths of males and females in breeding pairs, indicating that mate selection was random with respect to body size. There were no significant differences in body length between sampling dates during the field period in November 2021, suggesting that there is no divergence in spawning time between large and small individuals. Thus, neither of the two hypotheses were supported. Interestingly, males have significantly higher amount of breeding tubercles than females according to my results, which could be a selective factor in mate selection. However, the function of the tubercles is yet poorly understood.