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It is now acknowledged that mating system is a dynamic characteristic within species or populations. Indeed, behavioural characteristics shaping the mating system can vary at the inter‐individual level, providing raw material for sexual and natural selections, and at the intra‐individual level, because of phenotypic plasticity and ontogeny of individual behaviours. Social environment is an additional source of variation in sexual behaviours. By focusing on males of the parasitoid wasp Venturia canescens, we assessed how sexual behaviours (courtship and mating) vary between and within individuals, considering males' size as inter‐individual source of variation, and age and mating experience as intra‐individual sources of variation. Consequences of the variations in sexual behaviours at the individual level are appraised by quantifying the costs in longevity and offspring production incurred by (repeatedly) mated males. At the population level, we tested the "agility hypothesis" predicting that smaller males win the male–male competition to access females, resulting in a non‐random assortative mating by size and a negative sexual selection on body size. We showed that V. canescens males are polygynous and that mating incurred longevity cost. Old males had a higher probability to court females, but no mating advantage. Smaller males tended to have a higher mating probability, but size was not under sexual selection and there was a random mating pattern according to individual size. Male–male competition intensity did not influence pairing pattern but tended to influence mating dynamic. Overall, our results suggest that sexual behaviours tended to vary at the inter‐ and intra‐individual levels and the effect of social environment remains to be more precisely described. These variations may impact individuals' reproductive success with potential ecological and evolutionary consequences that are discussed. [ABSTRACT FROM AUTHOR]

In human populations, women consistently outlive men, which suggests profound biological foundations for sex differences in survival. Quantifying whether such sex differences are also pervasive in wild mammals is a crucial challenge in both evolutionary biology and biogerontology. Here, we compile demographic data from 134 mammal populations, encompassing 101 species, to show that the female's median lifespan is on average 18.6% longer than that of conspecific males, whereas in humans the female advantage is on average 7.8%. On the contrary, we do not find any consistent sex differences in aging rates. In addition, sex differences in median adult lifespan and aging rates are both highly variable across species. Our analyses suggest that the magnitude of sex differences in mammalian mortality patterns is likely shaped by local environmental conditions in interaction with the sex-specific costs of sexual selection. [ABSTRACT FROM AUTHOR]

Abstract: Sexual selection through female mate choice for genetic characteristics has been suggested to be an important evolutionary force maintaining genetic variation in animal populations. However, the genetic targets of female mate choice are not clearly identified and whether female mate choice is based on neutral genetic characteristics or on particular functional loci remains an open question. Here, we investigated the genetic targets of female mate choice in Alpine marmots (Marmota marmota), a socially monogamous mammal where extra‐pair paternity (EPP) occurs. We used 16 microsatellites to describe neutral genetic characteristics and two MHC loci belonging to MHC class I and II as functional genetic characteristics. Our results reveal that (1) neutral and MHC genetic characteristics convey different information in this species, (2) social pairs show a higher MHC class II dissimilarity than expected under random mate choice, and (3) the occurrence of EPP increases when social pairs present a high neutral genetic similarity or dissimilarity but also when they present low MHC class II dissimilarity. Thus, female mate choice is based on both neutral and MHC genetic characteristics, and the genetic characteristics targeted seem to be context dependent (i.e., the genes involved in social mate choice and genetic mate choice differ). We emphasize the need for empirical studies of mate choice in the wild using both neutral and MHC genetic characteristics because whether neutral and functional genetic characteristics convey similar information is not universal. [ABSTRACT FROM AUTHOR]

We investigated age-specific variation in survival of dominant individuals in a long-lived and monogamous mammal, the alpine marmot (Marmota marmota), from a large dataset collected during a 24-year intensive monitoring of a free-ranging population. We found evidence of actuarial senescence in dominant individuals for both sexes. Survivorship was constant with age until dominant marmots were between 6 and 8 years of age and declined markedly thereafter. No between sex differences occurred in the intensity of actuarial senescence, which might be related to the weak intensity of sexual selection in this socially monogamous mammal. More investigations are needed to know whether cooperative breeding, hibernation, and monogamy, which are key features of the alpine marmot life history, could have shaped the patterns of actuarial senescence we report. [ABSTRACT FROM AUTHOR]

Although long neglected, female competition is widespread and may have stronger evolutionary consequences than previously thought. In singular breeders, reproductive success is conditional on social status, and intrasexual competition for the dominant position can be particularly severe in females. Because the ability of females to secure the dominant position may strongly influence their fitness, a better understanding of the determinants of dominance maintenance is needed. Using a 21-year data set on Alpine marmots, Marmota marmota, we investigated the potential drivers of female dominance loss in a singularly breeding mammal. Particularly, we tested whether the dominant females' ability to retain their social position depended on the number and the characteristics (age, relatedness to dominant individuals) of potential competitors in the social unit. To identify the potential underlying mechanism, we further investigated how the number of subordinate females affected females' competitive ability. We found that the risk of losing the dominant position increased with the number of subordinate adult females in the group, but that the age of the subordinate females and their parentage relationships to the dominant individuals were unlikely to be driving dominance loss in this species. Moreover, when the number of potential competitors in the social unit increased, we observed a difference in body mass increase between the dominant and her subordinates leading to a decrease in the body mass difference between dominant females and their subordinate adult females, and ultimately to a higher risk of females losing the dominant position. Overall, our results showed that the number of potential competitors in a social group affects the females' ability to secure their dominant position, and suggested that this effect is mediated through changes in female body mass. [ABSTRACT FROM AUTHOR]

Three main hypotheses have been proposed to explain mate switching in monogamous species: the “better option” hypothesis, the incompatibility hypothesis, and the “forced divorce” hypothesis. We tested the predictions of these hypotheses for the first time in a monogamous mammal using long-term data from a natural population of Alpine marmots (Marmota marmota). Generally, pair disruption resulted in one of the pair members staying on the territory and re-pairing with a younger incomer, whereas the other disappeared from the territory. Replaced individuals were rarely found as dominant in a territory but were often injured or found dead. Individuals gained no benefit from mate switching: new mates were neither heavier, larger, or more heterozygote nor more genetically compatible than previous mates. Moreover, no increase in reproductive success was observed after re-pairing. The relationship between reproductive failure and occurrence of mate change was mainly due to infanticide by the incomer. Our results support the “forced divorce” hypothesis in the Alpine marmot and suggest that mate switching has strong consequences on breeding success. We discuss the importance of taking into account the cases of forced divorce while studying mate switching process and its evolutionary consequences in monogamous species. [ABSTRACT FROM PUBLISHER]