Aspects of white-tailed deer (Odocoileus virginianus) reproductive ecology remain understudied. The accuracy of the fetal age estimation equation in current use is unknown. Knowledge is also limited for female choice of secondary sexual traits like antlers and body size. To address previous fetal estimation equations, I developed a model that included litter characteristics using 110 fetuses with known ages of 54 to 175 days. To address female choice, I manipulated antler size and paired large and small males while controlling allometrically related traits. I then allowed estrus females to choose between pairs of segregated males with either large and small antlers or large and small bodies. My predictive fetal aging model generated more accurate fetal ages under a range of sample timing and composition variation. Using various behavioral indications of choice, I demonstrated that females prefer males with larger antlers and lack a preference for body size or age.

No description available.

Menopause, the cessation of reproductive capabilities before death, is a detrimental trait for female fitness, yet persists in all human populations. Numerous hypotheses have been published to describe how menopause has been maintained but failed to explain the origin and genetic basis of this trait. In 2013, Morton et al. proposed an influence of the mate choice behaviour, specifically a bias in mating ages that could allow for a trait, seemingly detrimental to fitness, to become neutrally fixed in a population. The goal of our research, presented herein, is to understand the role of the mating system, the sexual behaviour of a group, and especially mate choice, on the origin and evolution of menopause under a serial monogamy scenario. Analysis was conducted using an agent-based computational model that simulated populations. The populations were generated according to specified demographic parameters and reproduced according to a serial monogamy mating system. With the model, parameters were investigated including population lifespan, fecundity, pairing eligibility, age of loss of fecundity, and timing of decay in fecundity. Simulations revealed that, under certain restrictions, menopause can neutrally evolve. When mate choice was restricted to a particular age preference bias, menopause can appear with no diminishment of fitness. This novel mode for the origin of menopause is inferred to result from the accumulation of deleterious mutations in the female genome. By combining this ability of fertility-diminishing mutations to accumulate with research into the genetic basis of menopause, we provide a system for the evolution of menopause in a population of serial monogamy. / Thesis / Master of Science (MSc) / Despite decades of research into menopause, there remains no clear understanding of how this deleterious trait came to persist in the human population. It has been proposed that a bias in mate choice such that only younger females are chosen to mate can result in the accumulation of deleterious mutations, ultimately leading to menopause. We analyzed the evolution of menopause under a mating system of serial monogamy by a computational simulation. We came to three main conclusions. Firstly, under modern demographic parameters, menopause cannot evolve under serial monogamy. Secondly, in a population of shortened longevity, similar to chimpanzee, menopause neutrally appears at an age presently experienced by women. Finally, when mate choice is restricted such that only young females are eligible to mate within a system of serial monogamy, menopause can evolve. This means with the current mate choice shift towards older women, menopause can be postponed or even eliminated.

Menopause, the complete cessation of menstrual cycles, apparently is a detrimental trait, yet all women experience it. Numerous theories have been proposed to explain the origin of menopause, but none has been satisfactory. In 2013, Morton et al. proposed a mate choice hypothesis to explain menopause and, using a computational model, showed how a bias in mating (i.e., older men preferring younger women) could have allowed such an otherwise detrimental trait to evolve neutrally through accumulation of female fertility-reducing mutations. To investigate whether biased mating could affect fecundity and fertility in a real system, two experimental populations were established using Drosophila melanogaster. Older males were mated with younger females and vice versa. Information was obtained, including data on fecundity, fertility, ovariole and matured egg chambers, and lifespan, for experimental, age-restricted-mating and control populations. A negative effect on the fecundity and fertility of the younger-mating sex was observed in restricted-mating compared to control populations. Age-restricted mating had no effect on longevity. Menopause could evolve according to the mate choice hypothesis. / Thesis / Master of Science (MSc) / All animals are expected to remain fertile until they die. Menopause is an enigma and an unsolved problem in evolutionary biology. Numerous theories have been proposed to explain menopause, but there is no clear understanding of how this fertility reducing trait evolved in the human population. It has been proposed that biased mate choice i.e., preference for younger females can lead to accumulation of fertility-reducing mutations and the evolution of menopause. In this study, mate choice theory was tested using altered (biased) mating schemes with Drosophila melanogaster and the results support the mate choice theory of menopause.

No description available.

Contrary to traditional belief, the decisions that females make before, during and after mating shape its outcome and ultimately fitness. The aim of this thesis was to examine how females modify and adjust their mating decisions in line with social and environmental variability and how these directly and indirectly affect mating benefits. To address this aim I have formulated four main questions that correspond to chapters 2 to 6 in this thesis. Firstly I asked whether there was evidence for female choice being driven by mating benefits. More precisely, in chapter 2, I reviewed the literature in search of evidence for direct and indirect benefits in female choice among freshwater fish species. Direct mating benefits were defined as an increase in female’s reproductive success (number of offspring). Conversely, increases in offspring reproductive success were considered to be indirect benefits. The results showed that despite the multiple suggestions and the great amount of information available, to date there is still no evidence for both direct (increase of F1) or indirect (increase in F2) mating benefits, nor their influence in female mating decisions if freshwater fishes species. Furthermore, although polyandry occurred in more than 60% of the species reviewed, I was unable to confirm that polyandry was maintained because of indirect benefits. These findings justified the need to experimentally investigate the drivers of female mating decisions in freshwater fish species and lead to the questions addressed on chapters 5 and 6. For the experimental chapters 3-6 I used the Trinidadian guppy, Poecilia reticulata, as a model species. Their unique and remarkable ecological and biological characteristics coupled with easy maintenance in laboratory conditions make guppies an ideal species for behavioural studies. But in particular, the fact that guppies live in a promiscuous mating system where females despite being constantly harassed by males may be able to control paternity, makes guppies the ideal species to address my aims. The second question was how much were females in control of their mating decisions, and how social environment could limit these decisions. In particular, in chapter 3 I looked at how females adapt and adjust their mating decisions in line with extreme differences in population sex ratio. In chapter 4, I examined to what extent male sexual harassment affects female reproductive behaviours. Results from these two chapters indicated that female guppies have a remarkable reproductive plasticity that enable them to control their mating decisions. When faced with extreme differences in population sex ratio, female mating decisions were made in an optimal way that maximized the ratio of female reproductive benefits per investment. This translated into producing bigger offspring when in a strong female biased environment, than when in a male biased environment. Further, chapter 4 illustrated that female guppies can, despite high levels of male sexual harassment, be in control of their mating decisions. These two chapters demonstrated and have reinforced previous findings of the remarkable reproductive adaptation of female guppies to differences in the social environment. The third question I addressed was: do multiply mated females have greater direct or indirect benefits than single mated females? To answer this question I followed for the first time reproductive success of females over two generations. I measured fitness directly (number of F1 and F2) and took as well as multiple indirect measures of fitness components for two generations in search for evidence of direct and indirect mating benefits in explaining the maintenance of female multiple mating. The results of chapter 5 revealed that female guppies do not have a higher number of F1 and F2 from polyandry or either from mating with males possessing allegedly good quality traits. I, therefore, stressed the idea that potential differences in sexual selection pressure between laboratory and wild populations may influence the expression and intensity of mating benefits between thus explaining the difficulty of finding mating benefits. In my fourth and last question, I used a novel statistical approach based on the analysis of the dispersion in phenotypes, to look for potential alternative explanations for the prevalence of polyandry. The results of this analysis show offspring from multiple mated mothers were phenotypically more diverse than offspring from single mated mothers. Given the direct relationship between phenotypic diversity and potential fitness gains in stochastic systems, female guppies are likely to get greater benefits from mating with males with different phenotypes than with males with a particular sexual trait. This result provides an alternative explanation for the maintenance of polyandry in resource free systems. Overall the results of this thesis reinforce previous suggestions that female guppies are active participants in the mating process, and not necessarily limited to post-copulatory mechanisms of selection of sperm. It also showed the remarkable ability of females to adjust their reproductive investment in line with changes in the social conditions. Interestingly, my results contradict the commonly accepted assertion that females’ mating preference converges towards unique male sexual traits. This result stresses the need to look at alternative explanations to justify female mating decisions.

Learning and experience shape mate preferences in many species. My thesis investigates the role of experience on mating behavior of male and female sailfin mollies (Poecilia latipinna). In the first chapter I explore whether adult experience influences male sailfin molly mate preference for their sexual parasite, the Amazon molly (Poecilia formosa), and whether experience could account for reproductive character displacement (RCD) of male mate preference in this species. Sailfin males from sympatric populations show a stronger preference for conspecific females over Amazon mollies than do males from allopatric populations. I exposed males from sympatric and allopatric populations to either a sailfin female or an Amazon prior to a mating trial with an Amazon. For the allopatric population, males with recent experience with an Amazon directed fewer mating behaviors towards an Amazon during mating trials than did males with recent experience with a sailfin. Males from the sympatric population, however, performed the same amount of mating behaviors towards an Amazon regardless of experience. Thus adult experience influences mating preferences and suggests that experience may play a role in RCD in this species. In the second chapter I investigate whether a learned sensory bias could influence female mate preferences. Sensory biases that influence mate preferences can arise through selection on the sensory system in foraging and predator detection domains. I tested whether a learned preference originating outside of the mating domain, specifically a color-based food preference, can be transferred to a color-based preference for a male trait. I trained female sailfin mollies to associate either green or blue with food and then tested their preference for animated male sailfins featuring either a blue or green spot. I found that females did not prefer the male with the same color spot to which they had been conditioned. I discuss the problem of learned preference transfer and suggest directions for future research into the role of learning in sensory bias. / text

Despite recent increasing interest in the existence of animal personality, i.e. intra-individual consistency and inter-individual variation in the level of a behavioural trait, the evolutionary (and ecological) consequences of these consistent behavioural differences remain poorly understood. Some recent studies have revealed that variation in animal personalities might be linked to competitive interactions, resulting from natural selection. However, since personalities might similarly affect mate acquisition and reproductive success, it seems crucial to also explore their evolution under the framework of sexual selection theory. In this thesis I investigate the influence of personality on mate choice, reproductive success, female-male and male-male interactions, using zebra finches, Taeniopygia guttata, as a model species. After (I) I review the few existing studies assessing the link between sexual selection and personality, I propose a framework on the relationship between sexual selection and personality. Subsequently, (II) I show with different experimental approaches for the first time that (a) females choose males on the basis of their behaviour per se (male behaviour was experimentally disentangled from any appearance effects) whilst considering their own personality in their choice: less exploratory females did not distinguish between exploratory and non-exploratory appearing males, whereas moderately and highly exploratory females preferred similar males. (b) These preferences have an adaptive value to the exploratory females: exploratory females which had a behaviourally similar partner raised chicks in best condition but chicks in worst condition if they had a dissimilar partner. Low exploration females always raised chicks in intermediate condition, which may explain why they did not choose males on the basis of their exploratory behaviour. (c) I provide evidence that the combination of personalities in a pair, not only in terms of the level of the behaviour but also in terms of the behavioural consistency, influence reproductive success. However, this was only true for foster but not genetic parents, suggesting that behavioural rather than genetic compatibility (for the measured personality traits) is important for reproduction. (d) Moreover, some male behavioural characteristics appear to be a signal of male quality: highly exploratory foster males raised chicks (both males and females) in best condition, which themselves raised foster chicks of increased conditions. (e) Furthermore, a number of sex differences in personality traits (both level and consistency) are identified, including different responses to social interactions. (f) Additionally, I show how females with different exploratory tendencies differ in their movement patterns during mate choice. (g) Finally, I demonstrate that in competitive male-male situations, a measurement of condition, the fat score, and aggressive behaviour are positively correlated. These findings are set into sexual selection context (but other evolutionary processes are also considered) and both their ecological and evolutionary consequences are discussed. I outline how these results make a valuable contribution to the research field and discuss their potential to indicate new directions for future studies.

Over the last century, sexual selection has grown from a controversial theory into a vast field of theoretical and empirical research. Although Darwin outlined two major mechanisms within his theory, male-male competition and female mate choice, the latter has promoted a wealth of research by virtue of its complexity. Despite decades of research into how female preferences and sexually selected traits have evolved, there is still little consensus as to why females prefer the males they do. Preferences are thought to evolve from either direct selection on the preference, as females themselves benefit directly from mating with a preferred male, or through indirect selection on the preference via offspring fitness. In all cases however, female preferences should compensate for the costs of discriminating between potential mates, if they are to remain overall beneficial. The fitness benefits of mating with preferred males were investigated here using the fruitfly Drosophila simulans, employing a range of behavioural, phenotypic and quantitative genetic approaches. The findings presented here indicate that female Drosophila simulans do not gain directly from mating with a preferred male. Multiple mating can increase fecundity, although costs from male harassment can reduce the net benefit. They also indicate that females may benefit indirectly from mating with attractive males as attractiveness is heritable and sons of preferred males are themselves preferred. There is also evidence that attractive males are successful in both the pre- and post-copulatory sense, as preferred males are better sperm competitors than less-preferred males. However, although there appear to be benefits from preferred males via their sons, there appear to be no benefits from males via their daughters’ fitness. These findings collectively indicate that female preferences in Drosophila simulans are driven by indirectly selected benefits (via Fisherian sons), and that females benefit directly from mating multiply.

Distinguished ways are used to measure hierarchical rank between partners in surveys. Aim of this thesis was to study preference for partner of particular hierarchical rank towards respondent 1) according to rating of photographs, 2) according to respondent's ideas about his/her future partnership organization, 3) according to respondent's natural tendency to lead or to yield, and to compare these ways of preference assessment. Questionnaires from 95 female university students aged to 25 years inc. were processed. Respondents, who claimed they will submit their partner or they will take turns in subordination with their partner half and half, were more submissive in ordinary life than respondents, who claimed they will be equal to their partner. Expected connection between idea about future partnership organization or submissiveness in ordinary life and choice of photograph depicting figurant with particular signs of nonverbal dominance was not found. Nevertheless, differences in choices of photographs were found between females using hormonal contraceptives and females not using any hormonal contraceptives. Key words: mate-choice, dominance, submissiveness, attractiveness.