Polygyny is the most common mating system in mammalian species (95%), yet our understanding of polygynous systems and microevolutionary processes is still limited. Pinniped mating systems range from extreme polygyny (e.g. elephant seals) to sequential female defence by males and hence have often been used as models for mating system studies. Parentage analysis has enabled the examination of mating success, the identification of pedigrees, and the elucidation of social organisation, greatly enhancing our understanding of mating systems (Chapter 1). However, such analyses are not without pitfalls, with erroneous assignments common in open systems (i.e. when parental and offspring samplings are incomplete). We investigated the effects of the user-defined parameters on the accuracy of parental assignment using two commonly used parental allocation programme, CERVUS and PASOS (Chapter 2). We showed that inaccurate user-defined parameters in CERVUS and PASOS can lead to highly biased output e.g. the assignment rate at 95% CL of offspring with a sampled known mother to sampled males decreased from 58% to 32% when the proportion of candidate males sampled in the parameter options decreasing 4-fold. We found that the use of both CERVUS and PASOS for parentage assignment can increase the likelihood of correctly allocating offspring to sampled parents to 97% in our study system. Incorrect parental assignment can bias estimates of various biological parameters, such as lifetime reproductive success and mate choice preference, and hence bias ecological and evolutionary interpretations. Here, we propose solutions to increase the power of parentage assignment and hence decrease the bias in biological parameter estimates. In addition, we analysed the effects of the intrinsic bias in likelihood assignment approaches towards assigning higher probability of parentage on individuals with rare alleles and those with heightened offspring-parent matches, which increase with the number of homozygous loci (Chapter 3). We showed that, as a consequence of the algorithms employed in the programmes CERVUS and PASOS, heterozygote males with rare genotypes are assigned higher rates of parentage than males with common alleles. Consequently, where two males could both be biological fathers of a given offspring, parentage assignment will more often go to the male with the rarer alleles (most often in heterozygous loci). Thus, the commonly used parentage assignment methods may systematically bias the results of parentage analyses towards supporting the notion that females prefer more genetically unusual, most often heterozygous, males. Such a bias may sway investigators towards incorrectly supporting the concept that females choose genetically more unusual males for heterozygosity fitness benefits that underpin the good genes hypothesis, when in fact no such relationship may exist. In polygynous mammals, successful males mate with multiple females by competing with and limiting the access of other males to females. When the status of many males (age, size, health, genetic etc.) prevents them from achieving the primary mating tactic, theory predicts selection for a diversification of male mating tactics. Recent studies in pinnipeds have shown that observed male mating success was correlated to male paternity success in some species (elephant-seals), but not in others (grey seals). The existence of alternative mating strategies can explain those discrepancies. Chapter 4 implemented the guidelines provided in Chapter 2 and 3 and focused on the polygynous New Zealand fur seal Arctocephalus forsteri, predicting that 1) competition for females is likely to cause a diversification of male mating tactics; and 2) that alternative tactics can yield reproductive success. Our results indicated three male behavioural profiles; one corresponded to large territorial males and two illustrated a continuum of alternative tactics employed by non-territorial subordinate males. Our study highlights that holding a territory is not a necessary condition for reproductive success in a population of otariids. The degree of sexual size dimorphism in polygynous species is expected to increase with the degree of intra-sexual competition and in turn with the degree of polygyny. The life history of an individual is the pattern of resource allocations to growth, maintenance, and reproduction throughout its lifetime. Both females and males incur viability costs of mating and reproduction. However, male viability costs due to increase growth and male-male competition can be greater than female viability costs of mate choice and reproduction. Although an abundant literature on sexual dimorphism in morphology, physiology, and parasite infections is available, little is known on the intra-sexual differences in physiology and parasite infections associated to the reproductive success of different mating strategies in mammalian species. Chapter 5 examined the reproductive costs between territorial and subordinate males New Zealand fur seal related to their relative reproductive success using a multidisciplinary approach (behaviour, genetics, endocrinology, parasitology). We found that dominant New Zealand fur seal males endure higher reproductive costs due to the direct and indirect effects of high testosterone levels and parasite burdens. Our study highlights that holding a territory confers a higher reproductive success, but induces higher costs of reproduction that may impair survival. Understanding microevolutionary processes associated to polygynous systems is fundamental in light of the ongoing anthropogenic alteration of the environment through climatic variations and habitat reduction which ultimately affect opportunity for sexual selection and shape the life history trade-offs.

Sexual conflict has been proposed to be important for evolution, and is often implicated in population divergence and speciation through sexually antagonistic co-evolution (SAC). However, empirical tests of these ideas on field populations are few. How sexual conflict, and SAC, operates in the wild, remains an important unanswered question if we are to fully understand the role of sexual conflict in evolution in nature. Here, I studied sexual conflict over mating in the seed feeding bugs Lygaeus equestris and Lygaeus simulans. Firstly, I show that laboratory adapted populations of L. equestris that differ in the magnitude of sexual conflict also differ in aspects of their reproductive development and mating propensity, with the population displaying greater conflict load also mating more readily. Study of female receptivity to mating as an evolvable trait, that could be involved in conflict over mating, revealed moderate to low heritability at two age groups. To better understand variation in the expression of sexual conflict in the wild, field caught populations of L. equestris, ranging across its distribution, and also of its sister species, L. simulans, were assayed for the magnitude of sexual conflict over mating in common garden laboratory experiments. High female mating costs were apparent across the populations, but the magnitude of these costs did not vary. No consistent patterns of mating costs and life history variation were found however, arguing against close links between mating costs and life-history. Finally, I investigated whether populations displaying sexual conflict over mating have begun to diverge, and evolve reproductive isolation. I found no evidence of reproductive isolation, or variation in mating propensity, between populations of L. equestris when crossed in reciprocal no-choice mating trials. However, L. equestris and L. simulans did show pre-zygotic reproductive isolation albeit with asymmetries between the reciprocal crosses (L. simulans males were able to mate L. equestris females, but male L. equestris were largely unable to mate L. simulans females). As expected for close taxa that perhaps have not been diverged for long, pre-zygotic isolation was perhaps stronger than post-zygotic isolation, as F2 offspring were generated by some of the inter-specific crosses: gene flow can therefore occur between these species contrary to previous studies. My data suggest that sexual conflict over mating may reduce the likelihood of speciation through the evolution of male persistence, as well as promote it through population divergence.

The mating behaviour and reproductive ecology of the big-handed crab Heterozius rotundifrons was studied at Kaikoura between November 1997 and December 1998. H. rotundifrons was found at mean densities of 7.6 per m² (± 1.4) within the middle and low shore levels and varied little between seasons. The variance! mean ratio indicated that males and females aggregated within these shore levels. The sex ratio was significantly female biased during the majority of the year. Allometric growth rates indicated that males and females reached sexual maturity at 11 mm carapace width (CW). In males, spermatozoa production occurred between 9-9.99 mm CW. Ovigerous females were present every month except February. The first broods of the year were produced in March which coincides with a decrease in the female gonado-somatic index (GSI). These broods were incubated for approximately nine months whereas broods produced in August were incubated for only five months. Female brood production appeared to be cyclical, alternating between a winter incubation period and a summer incubation period. The completed cycle takes approximately three years with two broods produced during the cycle. Fecundity increased with female size but egg mortality was quite high (19%). Instantaneous mortality rate increased with increasing brood development. Females mate when recently moulted (soft-shelled). Although females moulted through out the year, in small numbers, there was a peak in female moulting during October and November. The operational sex ratio (OSR) was male biased during all months of the year. Females released an attractant prior to moulting which initiated pre-copulatory mate guarding by the male. Once the female moulted, copulation occurred approximately 6 h later. Copulation lasted for approximately 3 h and was followed by a period of post-copulatory mate guarding. Males increased the duration of post-copulatory mate guarding if another male was present. Large males out competed small males for receptive females. Males used their large cheliped to subdue competitors and to provide protection for the soft female. Mate guarding was shown to reduce cannibalism from other females. Spermatozoa are packaged in spermatophores within the vas deferens of males but are quickly dehisced within the spermathecae (ventral-type) of newly mated females. Last male to copulate probably achieves the highest level of paternity. Postcopulatory mate guarding by the male was found and ejaculates were found in discrete packets within the spermatheca. Sperm competition appeared to be important because large males displaced small males during copulation, males left when a female was still receptive and the females could retain sperm between moults. It is concluded that H. rotundifrons probably has a polygynous mating system in which males compete for soft females (female centered competition)

Polygyny is the most common mating system in mammalian species (95%), yet our understanding of polygynous systems and microevolutionary processes is still limited. Pinniped mating systems range from extreme polygyny (e.g. elephant seals) to sequential female defence by males and hence have often been used as models for mating system studies. Parentage analysis has enabled the examination of mating success, the identification of pedigrees, and the elucidation of social organisation, greatly enhancing our understanding of mating systems (Chapter 1). However, such analyses are not without pitfalls, with erroneous assignments common in open systems (i.e. when parental and offspring samplings are incomplete). We investigated the effects of the user-defined parameters on the accuracy of parental assignment using two commonly used parental allocation programme, CERVUS and PASOS (Chapter 2). We showed that inaccurate user-defined parameters in CERVUS and PASOS can lead to highly biased output e.g. the assignment rate at 95% CL of offspring with a sampled known mother to sampled males decreased from 58% to 32% when the proportion of candidate males sampled in the parameter options decreasing 4-fold. We found that the use of both CERVUS and PASOS for parentage assignment can increase the likelihood of correctly allocating offspring to sampled parents to 97% in our study system. Incorrect parental assignment can bias estimates of various biological parameters, such as lifetime reproductive success and mate choice preference, and hence bias ecological and evolutionary interpretations. Here, we propose solutions to increase the power of parentage assignment and hence decrease the bias in biological parameter estimates. In addition, we analysed the effects of the intrinsic bias in likelihood assignment approaches towards assigning higher probability of parentage on individuals with rare alleles and those with heightened offspring-parent matches, which increase with the number of homozygous loci (Chapter 3). We showed that, as a consequence of the algorithms employed in the programmes CERVUS and PASOS, heterozygote males with rare genotypes are assigned higher rates of parentage than males with common alleles. Consequently, where two males could both be biological fathers of a given offspring, parentage assignment will more often go to the male with the rarer alleles (most often in heterozygous loci). Thus, the commonly used parentage assignment methods may systematically bias the results of parentage analyses towards supporting the notion that females prefer more genetically unusual, most often heterozygous, males. Such a bias may sway investigators towards incorrectly supporting the concept that females choose genetically more unusual males for heterozygosity fitness benefits that underpin the good genes hypothesis, when in fact no such relationship may exist. In polygynous mammals, successful males mate with multiple females by competing with and limiting the access of other males to females. When the status of many males (age, size, health, genetic etc.) prevents them from achieving the primary mating tactic, theory predicts selection for a diversification of male mating tactics. Recent studies in pinnipeds have shown that observed male mating success was correlated to male paternity success in some species (elephant-seals), but not in others (grey seals). The existence of alternative mating strategies can explain those discrepancies. Chapter 4 implemented the guidelines provided in Chapter 2 and 3 and focused on the polygynous New Zealand fur seal Arctocephalus forsteri, predicting that 1) competition for females is likely to cause a diversification of male mating tactics; and 2) that alternative tactics can yield reproductive success. Our results indicated three male behavioural profiles; one corresponded to large territorial males and two illustrated a continuum of alternative tactics employed by non-territorial subordinate males. Our study highlights that holding a territory is not a necessary condition for reproductive success in a population of otariids. The degree of sexual size dimorphism in polygynous species is expected to increase with the degree of intra-sexual competition and in turn with the degree of polygyny. The life history of an individual is the pattern of resource allocations to growth, maintenance, and reproduction throughout its lifetime. Both females and males incur viability costs of mating and reproduction. However, male viability costs due to increase growth and male-male competition can be greater than female viability costs of mate choice and reproduction. Although an abundant literature on sexual dimorphism in morphology, physiology, and parasite infections is available, little is known on the intra-sexual differences in physiology and parasite infections associated to the reproductive success of different mating strategies in mammalian species. Chapter 5 examined the reproductive costs between territorial and subordinate males New Zealand fur seal related to their relative reproductive success using a multidisciplinary approach (behaviour, genetics, endocrinology, parasitology). We found that dominant New Zealand fur seal males endure higher reproductive costs due to the direct and indirect effects of high testosterone levels and parasite burdens. Our study highlights that holding a territory confers a higher reproductive success, but induces higher costs of reproduction that may impair survival. Understanding microevolutionary processes associated to polygynous systems is fundamental in light of the ongoing anthropogenic alteration of the environment through climatic variations and habitat reduction which ultimately affect opportunity for sexual selection and shape the life history trade-offs.

No description available.

<p> </p> <p>The degree of self-fertilization in a population determines levels of genetic variation and high selfing rates could thus limit future adaptive potential. Theory predicts that intermediate selfing rates should not persist, yet many plants exhibit mixed mating. Cleistogamy is a floral heteromorphism where individuals produce both showy potentially outcrossing chasmogamous flowers and closed obligately selfing cleistogamous flowers. Reproduction via cleistogamous flowers is thought to be beneficial because of their greater energetic economy compared to chasmogamous flowers but can be costly if selfing leads to inbreeding depression or accelerates the fixation of deleterious mutations within populations. Cleistogamy has evolved independently multiple times and can be used to study the maintenance of adaptive mixed mating. To investigate this, I estimated the costs and benefits of selfing in three populations of <em>Ruellia humilis </em>Nutt (Acanthaceae) in greenhouse common garden experiments. To quantify the costs, I performed hand pollinations and quantified fitness components of progeny resulting from selfing and outcrossing within- and between-populations. To quantify the relative energetic advantage of cleistogamous flowers, I measured dry flower mass, fertility, seed number per fruit, and pollen-ovule ratios of both types of flowers. I found negative cumulative inbreeding depression in all populations, indicative of selfed progeny outperforming outcrossed progeny. While the fitness consequences of between population outcrossing ranged from heterosis to outbreeding depression. When looking at the energetic benefits of selfing, I found that the cost of reproduction via cleistogamous flowers was between 3 and 14-fold less than the cost for outcrossing flowers. Finally, I combined data on inbreeding depression and the energetic costs of reproduction and found that chasmogamous flowers of <em>R. humilis </em>must provide between a 3 to a 45-fold fitness advantage to be maintained, the magnitude of which was dependent upon maternal population. Overall, I conclude that none of the existing hypotheses are sufficient enough to provide the selective advantage needed to explain the persistence of chasmogamous flowers in <em>R. humilis</em>. Without any supported explanations for the maintenance of mixed mating, the exploration of genetic constraints on the loss of chasmogamous flowers could solve this long-standing mystery. </p>

Neurodegenerative diseases, such as Parkinson’s disease (PD), likely initiate their pathologies primarily within the brain and later manifest themselves in daily behavioral functions. In patients with PD, the loss of dopaminergic neurons in the basal ganglia results in sensorimotor deficits, including tremor, bradykinesia, olfactory function loss, speech/voice loss, and eating disorders. Although not much is known about the etiology of Parkinson’s disease, extensive studies have focused on correlating different signs of motor degradation with the degree of dopaminergic neuron loss. Despite the fact that different animal models and diverse behavioral methods have been developed to further characterize limb motor function loss, the loss of fine oromotor function, which includes eating/biting disorders and voice/speech loss, has been largely overlooked due to its intrinsic complexity as well as the lack of a precise method for quantitative description. An animal model was developed for the study of oromotor deficits in PD that utilizes the production of ultrasonic vocalization in lab rodents. Parkinsonian animals suffer the same symptoms in their vocalization compared to human PD patients: a significant drop of intensity and pitch variation. Furthermore, a newly developed biting test provided evidence that the animal’s oromotor function have been compromised due to dopamine loss. Overall, these studies show that qualitative analysis of the ultrasonic vocalizations (USVs) of laboratory rats can serve as a sensitive behavioral biomarker for the detection of subtle oromotor deficits in neurodegenerative diseases. / text

Social organization of a species may impact behavior, reproductive ecology, mating system, population genetic structure and overall fitness. A spectrum of sociality exists from solitary individuals to aggregations to integrated, highly related groups. A large body of knowledge exists for sociality and life-history characteristics of ground-dwelling sciurids, including several overarching models to explain the evolution of sociality. These models predict round-tailed ground squirrels (Xerospermophilus tereticaudus) to be solitary based on small body size (~125g), relatively long period of activity (January-June) and a short period of adult-juvenile overlap. However, previous behavioral observations suggest round-tailed ground squirrels have a clustered matrilineal structure with a suite of social behaviors, suggesting that they may represent a unique outlier in ground squirrel sociality models. Within the population of round-tailed ground squirrels at the Casa Grande Ruins National Monument in Coolidge, Arizona, USA, rates of amicable and agonistic interactions between adults were low, with no relationship between relatedness of individuals and rates of social interactions. No population substructure was evident with Bayesian analyses, global or pairwise F(ST) values, and average relatedness among females did not differ from males. Contrary to previous behavioral studies, round-tailed ground squirrels did not have high levels of social behavior, nor did they form significant genetic subpopulation structuring. The active season of round-tailed ground squirrels closely followed patterns of precipitation and peak resource availability. Body mass differed between males and females, across years, and within seasons. Males were heavier than females at emergence, prior to mating and pre-hibernation, but not when females began gestation. Emergence of litters and litter size are related to amount and timing of winter rainfall. Foraging and vigilance behaviors compose 64-66% of the activity budget, but differ in that males spend a greater proportion of time foraging, whereas females spend a greater proportion of time vigilant. Round-tailed ground-squirrels have a polygynandrous mating system. Polygyny was evident in 2004, 2005, and 2006, and multiple paternity occurred in the majority of litters with 2.5 sires/litter; litter size was positively correlated with the number of sires. These findings support predictions generated by sociality models for ground-dwelling squirrels.

Life history theory attempts to explain between- and within-species variation in maturational and reproductive patterns, whereas sexual selection attempts to explain between- and within-sex differences in intersexual mate choice and intrasexual competition for members of the opposite sex. These two expansive evolutionary theories have been used by developmental scientists and social/personality psychologists to explain the variation observed in human reproduction, including the timing of reproductive events and individual differences in orientation toward mating and parenting. In Part I of the following paper, I review research related to life history theory and sexual selection in humans. I then show how integrating the principles of sexual selection with life history models of human reproductive strategies can address existing limitations. In Part II, I empirically examine many of the unique propositions that emerge from theoretical integration using a longitudinal dataset on adolescent development. Under investigation is an expanded model of sociosexual development that incorporates key principles from Belsky, Steinberg, and Draper's (BSD) psychosocial theory and sexual selection theory. I specifically examine the role of early rearing conditions within the home, as specified by BSD, and self-perceived mate value, as highlighted by a sexual selection perspective, on timing of sexual debut and sexual risk taking. The current study combines variable-centered and person-centered methods to assess specialized developmental trajectories. In total, the study provides novel support for BSD theory, while also highlighting needed revisions to account for the role of self-perceived mate value on adolescent sexual behavior.

Ants and other social Hymenoptera (social bees and wasps) have a remarkable mating strategy. Social Hymenoptera live in societies where reproduction is monopolized by a fertile caste consisting of males and queens. On the other hand, the logistical tasks of the colony are carried out by a sterile female caste known as workers. Reproductive individuals mate during a single bout early in their life and will never engage in additional reproductive events later on. Males die soon after mating while queens store millions of sperm cells in a specialized organ, the spermatheca. Queens will use this sperm stock to fertilize eggs during the rest of their life that can last up to several decades. With a record of 28.5 years in the black garden ant, ant queens have the longest lifespan recorded to date among the social Hymenoptera. In my thesis, I addressed three aspects of ant queen reproduction. First, I tested the effect of mating on the expression of several genes involved namely in fecundity, longevity and immunity. I found that mating induces an up-regulation of the yolk precursor vitellogenin and of the antimicrobial peptide defensin. Second, I measured the intensity of different immune responses in male and queen genital organs in order to determine which immune pathways are activated to protect sperm. Antimicrobial peptide genes are expressed in the genital tract of both sexes and the queen spermatheca is capable of strongly inhibiting bacterial growth. The immune melanization response is, however, overall inactive in the organs tested probably because its unspecific mode of action and cytotoxic by-products are likely to damage sperm cells. Immunity thus seems to be closely regulated in organs that are in contact with sperm. Third, I determined if activation of the queen immune system had an impact on the survival of sperm stored in the spermatheca. There is no detectable effect in young newly mated queens whereas, in one year old queens, immune activation induces a significant reduction in sperm viability. Life stage thus seems to influence queen ability to preserve sperm viability in the event of an immune challenge. In addition, one year old queens have higher sperm viability than newly mated queens suggesting queens are able to displace dead sperm cells from their spermatheca. Finally, I relied on the well-established sequence of behaviors inherent to the early life of ant queens to try to uncover the largely unknown roles of inotocin, the insect ortholog of the vertebrate hormones oxytocin and vasopressin, in regulating insect behavior. I measured gene expression of the inotocin receptor and found that it is highly expressed during social and reproductive behaviors, which is consistent with previous results in vertebrates. Inotocin might thus also be involved in modulating these behaviors in insects, but further studies are needed to be able to fully understand this complex signaling system. Overall, I show that reproduction and immunity are closely linked in ant queens and that the latter provide promising models for investigating the roles of hormones in insects. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished