Sexual interactions play an important role in generating sexual selection and antagonistic co-evolution. These forces can shape differences between the sexes, but also have the potential to generate population divergence and contribute to speciation. The aim in this thesis was to provide new insights into the genes involved in different stages of female sexual interactions, using Drosophila as a model system. In chapter 2 I tested whether a candidate gene (period) that influences species-specific rhythmic characteristics in male courtship song in D. melanogaster also has a pleiotropic effect on female song preference. Using mutant and transgenic strains I found support for this. In chapter 3 I examined further how females respond to the song at the level of gene expression, using microarrays. Expression profiles revealed modest changes in transcripts abundance overall, which were dominated by antennal olfactory genes, neuropeptide encoding genes and immunity genes. Many of these have previously been found to respond to mating. In chapter 4 I therefore studied further two of these genes, TurandotM and TurandotC and their role in female post-mating fitness. Using RNA interference I found that knocking down these genes influenced immediate fecundity. In chapter 5 I focused on analysing post-mating gene expression patterns in relation to sexual selection in D. pseudoobscura using microarrays. I explored the consequences of experimental variation in female promiscuity on gene expression divergence as a whole, and in response to mating. I found large-scale expression divergence between monandrous and polyandrous females after 100 generations of experimental evolution. Experimental polyandry increased the expression of genes that show female-biased expression in wild-type individuals and decreased male- biased gene expression. Females experiencing no sexual selection showed the opposite pattern. Out of the genes affected by mating, the majority showed increased expression in polyandrous compared to monandrous females, with enrichment e.g. in oogenesis-related genes.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfillment of the requirement for the degree of Doctor of Philosophy JOHANNESBURG January 1996 / I investigated some evolutionary implications of female mate choice in a feral population of guppies (Poecllia reticultuai. I performed correlative and manipulative experiments to establish the relationship between female mate choice and other sexually selective forces including iutermale aggression and sneak copulation, and the exaggerated secondary sex characters (ornaments) of male guppies. Orange (carotenoid) ornamentation is the best predictor of male attractiveness and mating success, a relationship which held under manipulation. Black (melanin) is sometimes correlated with male mating success. Mnnipulatiug the black area of males reveals that it is important to male attractiveness, and this appears to be in the form of a signal amplifier of male orangeness. This is the fi.st experimental evidence for a visual signal amplifier. For both orange and black areas, the relationship between absolute area and fluctuating asymmetry is positive and significant, suggesting that neither is n signal of male condition. These results arc Interpreted in the context of theories of the evolution of multiple male ornaments. Females are able to express their preference for orange with the first mature male they ever encounter, uuggestlng an important role for genetic determination in female preferences. This is corroborated by high repeatability of female mate choice behaviour. Experience modifies a female's preferences as she is able to adjust her response to a male in relation to the ornamentation of (at least) the previous male she saw. Mate copying has no mensurable effect on the outcome of female mate choice decisions. / MT2016

Although sexual selection in nature has been studied intensively, much is still unknown about the evolution of mating systems in wild populations: for example, how male competition and female choice interact, or the effect of environmental heterogeneity on selection. Further, important questions remain about the consequences of sexual selection for genetic structuring and genetic variation within populations. In this thesis, I investigate the causes and consequences of sexual selection in a polygynous mammal, the red deer Cervus elaphus. This species is characterized by high male reproductive skew resulting from competition to defend harems of females. Here however, I present evidence for previously unappreciated complexity in the mating system, in terms of female mating behaviour and environmental influences on male-male competition. I then go on to investigate the consequences of non-random mating on co-ancestry and inbreeding in the population. Finally, I investigate methods for separating genetic and environmental sources of covariance between individuals. Specifically, I: (i) Show a surprising degree of female mobility during the breeding season (the 'rut‘). Around 40% of females change harem when in oestrus and almost half of these movements result in paternity for the novel male; however I show that these movements are unlikely to be explained by female choice for mates. (ii) Reveal that variance in male mating success is affected by variation in ecological parameters, in particular the interaction between the number of immigrant males in the rutting population and the temporal synchrony of females. (iii) Demonstrate substantial inter-individual differences in the plasticity of acoustic signals produced by rutting males with changes in social context. (iv) Reveal the existence in this population of three rarely reported mating behaviours in polygynous mammals. I find around a fifth of females mate with the same male in multiple years; female relatives frequently mate with the same male; and males rut in locations close to their relatives. Further, I show these behaviours are associated with higher co-ancestry and inbreeding in the population than expected under random mating. (v) Finally, I investigate how spatial associations between relatives upwardly bias estimates of heritability in four phenotypic traits. I do this by accounting for shared environment effects in animal models by i) inclusion of spatial autocorrelation parameters and ii) a novel multi-matrix approach.

Animals’ personality traits are defined as consistent behavior tendencies and the function of them in life-history strategy and reproductive success has been given a lot of explanations in a large amount of research. However, the behavior consistency of individuals in different sexes, mating status and selection regimes is rarely mentioned. In this research, we were interested in personality traits and their consistency in inter-individuals and intra-individuals, and proposed that with the removal of fecundity selection males would evolve to be more female-like and decrease their locomotor activity, and copulation would change the physiological status of females and thus alter their levels of activity.   In the experiment, seed beetles (Callosobruchus maculatus) that were artificially selected in monogamy, polygamy and male-limited selection regimes were weighed, dropped in a designed arena and their behaviors were recorded with a camera for four minutes in the first day when they were newborn and virgin. In the next day, the virgin beetles were randomly paired to mate, weighed afterwards, and dropped in the arena again for videoing the same setting as yesterday. In data collection step, with these videos four behaviors types including walking, entering squares, time spent on roof and entering a new area were observed, scored and noted down. To process the data, we made correlation analysis and it was found that walking, entering square and a new area were positively correlated. After building the linear mixed effect models we found that sex together with mating significantly act in modifying beetles’ behaviors, males were more active than females but the difference was narrowed after mating, and copulation caused a significant increase in the level of locomotor activity in females. To our disappointment, selection regimes did not have any significant impact on locomotor activity. Our work gave an insight that copulation changed individuals’ behaviors more in females than in males and dimorphic expression of sex-biased genes differed due to mating effect.

The difference in evolutionary interests of males and females can select for traits that favour an individual??s fitness at the expense of their mate??s lifetime fitness. Despite the widespread occurrence of this sexual conflict over reproductive interactions, however, research to date has largely focused on the fitness costs imposed on females by manipulative males. Empirical evidence is particularly sparse for how mating can also be costly for males, the genetic structure of traits involved in reproductive interactions, and how sexual conflict can modify sexual selection in general. My aim was to explore the broader evolutionary consequence of sexual conflict and male-female interactions. In the nuptial-feeding Australian ground cricket, Pteronemobius sp., I used an experimental evolution approach to explore how diet and sexual conflict interact to determine the costs of mating. In the Australian black field cricket, Teleogryllus commodus, I used molecular and quantitative genetic approaches to characterise the fitness consequences and genetic basis of spermatophore attachment, a trait at the centre of inter-locus sexual conflict, and then related this to both condition and male attractiveness. Finally, in T. commodus, I quantified how sexual conflict alters the sexual selection acting on male sexual traits and how this in turn shapes genetic architecture and the persistence of additive genetic variance. My results demonstrate the complex nature of reproductive interactions between males and females. Importantly, I show that diet can mediate the expression of sexual conflict in a mating system and shape the evolution of male life-span. I also show that reproductive interactions influence the fitness benefits that both male and females obtain from mating in ways that are not predicted by current theory and that much of the potential for such traits to co-evolve is via a common genetic association with condition. Finally, I demonstrate that sexual conflict can profoundly modify the process and outcome of sexual selection, thereby influencing how additive genetic variation is maintained in a suite of male sexual traits. These results highlight the need for a greater integration of sexual conflict and sexual selection theory as the evolutionary potential and significance of sexual conflict may currently be underestimated.

Males of the Mexican lizard Sceloporus minor (Phrynosomatidae) exhibit striking variation in dorsal coloration, both within and among populations, which may have arisen by sexual selection. The possible significance of this trait was investigated through a combination of observational and experimental approaches. This research revealed that males in one population (La Manzana) in NW Hidalgo exhibit three discrete color morphs (blue, yellow, red) each characterized by morphological, physiological and behavioral differences. Furthermore, these morphs can be identified by an objective approach to color assessment (spectroradiometry). In addition, males in a second population (Escalerillas) from SE San Luis Potosí were also found to occur in at least two color morphs (yellow and red), suggesting that color polymorphism may be general in this species. The hypothesis of sensory exploitation by male contest competition was tested for S. minor from Escalerillas; however, no support for this hypothesis was found. Overall, results from this study are consistent with the hypothesis of alternative reproductive tactics in S. minor.

Thesis (Ph.D.)--McMaster University, 2005. / Advisor: Bennett Galef. Includes bibliographical references. Also available online.

Sexual differences are dramatic and widespread across taxa. However, a common genome between males and females should hinder phenotypic divergence. In this thesis I have used experimental, genomic, and theoretical approaches to study processes that can facilitate and maintain differences between males and females. I studied two mechanisms for the evolution of sexual dimorphism - condition-dependence and gene duplication. If sex-specific traits are costly, then individuals should only express such traits when they possess enough resources to do so. I experimentally manipulated adult condition and found that the sex-biased gene expression depends on condition. Second, duplication events can permit different gene copies to adopt sex-specific expression. I showed that half of all duplicate families have paralogs with different sex-biased expression patterns between members. I investigated how current sexual dimorphism may support novel dimorphism. With regards gene duplication, I found that related duplicates did not always have different expression patterns. However, duplicating a pre-existing sex-biased gene effectively increases organismal sexual dimorphism overall. From a theoretical perspective, I investigated how sexually dimorphic recombination rates allow novel sexually antagonistic variation to invade. Male and female recombination rates separately affect invasion probabilities of new alleles. Finally, I examined the assumption that a common genetic architecture impedes the evolution of sexual dimorphism. First, I conducted a literature review to test whether additive genetic variances in shared traits were different between the sexes. There were few significant statistical differences. However, extreme male-biased variances were more common than extreme female-biased variances. Sexual dimorphism is expected to evolve easily in such traits. Second, I compared these results to findings from the multivariate literature. In contrast to single trait studies, almost all multivariate studies of sexual dimorphism have found variance differences, both in magnitude and orientation, between males and females. Overall, this thesis concludes that sexual dimorphism can evolve by processes that generate novel sexual dimorphism or that take advantage of pre-existing dimorphism. Furthermore, a common genome is not necessarily a strong barrier if genetic variances differ between the sexes. It will be an exciting challenge to understand how mutation and selection work together to allow organisms differ in their ability evolve sexual dimorphism.

<p>Despite early neglect, recent studies of sexual selection have shown a renewed interest in female reproductive strategies. Clearly the traditional portrayal of female animals as passive participants in mating is incorrect, but much is still unknown about female reproductive strategies, including the extent of female mate choice. The primary goal of this dissertation was to explore the role of female mate choice in mantled howling monkeys (<italic>Alouatta palliata</italic>), a species in which males have previously been assumed to control mating. </p><p>From March 2006 through February 2007, I used continuous focal-animal sampling to record the behavior of adult female mantled howlers at Hacienda La Pacifica, Guanacaste, Costa Rica. The focal animals in the study were nine adult females in a social group that has been regularly monitored since 1984. There were also three capture sessions performed by K. Glander to collect blood samples for genetic paternity analysis. A total of 29 individuals in the study group and eight adult males from surrounding groups were captured.</p><p>The genetic paternity analyses were largely inconclusive. Of the eight microsatellite markers used previously in this species, only four were polymorphic in this sample. Additionally, nearly half (7 of 16) of the purported mothers were excluded at one locus. Assuming the mother was unknown allowed determination of genetic paternity in only one case. In terms of behavior, females were largely responsible for soliciting copulations, but female mate choice did not appear to be a major factor. Females almost never rejected copulations (3.3% of copulation attempts) and mated with multiple males in 77.8% of female cycles. </p><p>The lack of conclusive genetic paternity data leaves open the possibility of post-copulatory female choice. However, explanations exist for the apparent lack of female mate choice in this species. Because males must attain alpha status to remain in a group, differences in inherent quality may be low among group males. The potential for small differences among males in a social group, combined with the fact that females disperse from their natal group, suggests that female mate choice may occur primarily in choosing a group during dispersal.</p> / Dissertation

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Supervisor: Michael J. Ryan. Vita. Includes bibliographical references. Also available from UMI.