Sexual conflict. The evolution of infanticide by males in mammalian societies.

Male mammals often kill conspecific offspring. The benefits of such infanticide to males, and its costs to females, probably vary across mammalian social and mating systems. We used comparative analyses to show that infanticide primarily evolves in social mammals in which reproduction is monopolized by a minority of males. It has not promoted social counterstrategies such as female gregariousness, pair living, or changes in group size and sex ratio, but is successfully prevented by female sexual promiscuity, a paternity dilution strategy. These findings indicate that infanticide is a consequence, rather than a cause, of contrasts in mammalian social systems affecting the intensity of sexual conflict.This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version will be published in Science (http://www.sciencemag.org/magazine)

Connaissances actuelles sur les méthodes de lutte contre les helminthoses digestives du cheval

Cette étude bibliographique vise à faire le point sur les différentes méthodes de lutte actuelles contre les helminthoses digestives des chevaux. Après un bref rappel phylogénique et biologique sur les strongles des équidés, les protocoles de prévention couramment utilisés sont passés en revue. La chimioprophylaxie, pratique largement majoritaire aujourd'hui, est envisagée de manière approfondie, avec une description des molécules disponibles et des précisions quant à leur mode d'action et leurs spectres respectifs. Le phénomène de la résistance des strongles aux anthelminthiques est abordé ensuite : définition, méthodes diagnostiques et épidémiologie descriptive (espèces parasitaires concernées, classes thérapeutiques impliquées et distribution géographique) sont présentées. On prête une attention particulière aux aspects épidémiologiques analytiques, à savoir le déterminisme génétique et environnemental de l'apparition et du développement de la résistance. Les effets de chacun des facteurs biologiques connus, respectivement liés aux parasites, aux antiparasitaires et à la conduite d'élevage sont ainsi discutés en détail. Une dernière partie est consacrée à la gestion de ce problème, et détaille les stratégies permettant de retarder son émergence et d'enrayer son extension. Enfin, les perspectives présentes et à venir en matière de lutte antiparasitaire chez les chevaux sont évoquées

Social network inheritance and differentiation in wild baboons

Immatures' social development may be fundamental to understand important biological processes, such as social information transmission through groups, that can vary with age and sex. Our aim was to determine how social networks change with age and differ between sexes in wild immature baboons, group-living primates that readily learn socially. Our results show that immature baboons inherited their mothers' networks and differentiated from them as they aged, increasing their association with partners of similar age and the same sex. Males were less bonded to their matriline and became more peripheral with age compared to females. Our results may pave the way to further studies testing a new hypothetical framework: in female-philopatric societies, social information transmission may be constrained at the matrilineal level by age- and sex-driven social clustering

Early growth, dominance acquisition and lifetime reproductive success in male and female cooperative meerkats.

In polygynous species, variance in reproductive success is higher in males than females. There is consequently stronger selection for competitive traits in males and early growth can have a greater influence on later fitness in males than in females. As yet, little is known about sex differences in the effect of early growth on subsequent breeding success in species where variance in reproductive success is higher in females than males, and competitive traits are under stronger selection in females. Greater variance in reproductive success has been documented in several singular cooperative breeders. Here, we investigated consequences of early growth for later reproductive success in wild meerkats. We found that, despite the absence of dimorphism, females who exhibited faster growth until nutritional independence were more likely to become dominant, whereas early growth did not affect dominance acquisition in males. Among those individuals who attained dominance, there was no further influence of early growth on dominance tenure or lifetime reproductive success in males or females. These findings suggest that early growth effects on competitive abilities and fitness may reflect the intensity of intrasexual competition even in sexually monomorphic species

A female signal reflects MHC genotype in a social primate.

BACKGROUND: Males from many species are believed to advertise their genetic quality through striking ornaments that attract mates. Yet the connections between signal expression, body condition and the genes associated with individual quality are rarely elucidated. This is particularly problematic for the signals of females in species with conventional sex roles, whose evolutionary significance has received little attention and is poorly understood. Here we explore these questions in the sexual swellings of female primates, which are among the most conspicuous of mammalian sexual signals and highly variable in size, shape and colour. We investigated the relationships between two components of sexual swellings (size and shape), body condition, and genes of the Major Histocompatibility Complex (MHC) in a wild baboon population (Papio ursinus) where males prefer large swellings. RESULTS: Although there was no effect of MHC diversity on the sexual swelling components, one specific MHC supertype (S1) was associated with poor body condition together with swellings of small size and a particular shape. The variation in swelling characteristics linked with the possession of supertype S1 appeared to be partially mediated by body condition and remained detectable when taking into account the possession of other supertypes. CONCLUSIONS: These findings suggest a pathway from immunity genes to sexual signals via physical condition for the first time in females. They further indicate that mechanisms of sexual selection traditionally assigned to males can also operate in females.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Dynamics of intersexual dominance in a highly dimorphic primate

Intersexual dominance, which is measured by the probability that members of one sex elicit submission of members of the other sex during agonistic interactions, is often skewed in favor of males. However, even in sexually dimorphic species, several factors may influence intersexual dominance. Here, we use an 8-year dataset to examine the dynamics of intersexual dominance in wild-living mandrills (Mandrillus sphinx). Mandrills exhibit an extreme male-biased sexual size dimorphism but females show pronounced kin-differentiated social relationships and occasionally form coalitions against males. We established intersexual hierarchies across consecutive 6-month time blocks, representing either mating or birth seasons. Although females appeared to outrank 11% of males, they elicited male submission in only 2% of agonistic interactions against males. This discrepancy is likely due to the temporary residency of most males in the exceptionally large mandrill groups, the sexually coercive male mating strategies and the scarce number of agonistic interactions within most dyads, that may limit hierarchical inferences. In a second step, we found that the intersexual hierarchy mixes the intrasexual ones respecting their respective order. Females outranked mostly young and old males during the mating (vs. birth) season and social integration was positively correlated to dominance status in both sexes. In a third step, we found that females win more conflicts against young or old males which are closer to them in the intersexual hierarchy. These results extend our understanding of female-male dominance relationships by indicating that female mandrills occasionally outrank males who are considerably larger than them, and that a combination of demographic and social factors can influence the intersexual hierarchy

Competitive growth in a cooperative mammal.

In many animal societies where hierarchies govern access to reproduction, the social rank of individuals is related to their age and weight and slow-growing animals may lose their place in breeding queues to younger 'challengers' that grow faster. The threat of being displaced might be expected to favour the evolution of competitive growth strategies, where individuals increase their own rate of growth in response to increases in the growth of potential rivals. Although growth rates have been shown to vary in relation to changes in the social environment in several vertebrates including fish and mammals, it is not yet known whether individuals increase their growth rates in response to increases in the growth of particular reproductive rivals. Here we show that, in wild Kalahari meerkats (Suricata suricatta), subordinates of both sexes respond to experimentally induced increases in the growth of same-sex rivals by raising their own growth rate and food intake. In addition, when individuals acquire dominant status, they show a secondary period of accelerated growth whose magnitude increases if the difference between their own weight and that of the heaviest subordinate of the same sex in their group is small. Our results show that individuals adjust their growth to the size of their closest competitor and raise the possibility that similar plastic responses to the risk of competition may occur in other social mammals, including domestic animals and primates.The KMP is supported and organized by the Universities of Cambridge and Zurich. This research was supported by NERC (Grant RG53472) and the ERC (Grant 294494)

Assessing the recovery of Y chromosome microsatellites with population genomic data using Papio and Theropithecus genomes

Y chromosome markers can shed light on male-specific population dynamics but for many species no such markers have been discovered and are available yet, despite the potential for recovering Y-linked loci from available genome sequences. Here, we investigated how effective available bioinformatic tools are in recovering informative Y chromosome microsatellites from whole genome sequence data. In order to do so, we initially explored a large dataset of whole genome sequences comprising individuals at various coverages belonging to different species of baboons (genus: Papio) using Y chromosome references belonging to the same genus and more distantly related species (Macaca mulatta). We then further tested this approach by recovering Y-STRs from available Theropithecus gelada genomes using Papio and Macaca Y chromosome as reference sequences. Identified loci were validated in silico by a) comparing within-species relationships of Y chromosome lineages and b) genotyping male individuals in available pedigrees. Each STR was selected not to extend in its variable region beyond 100 base pairs, so that loci can be developed for PCR-based genotyping of non-invasive DNA samples. In addition to assembling a first set of Papio and Theropithecus Y-specific microsatellite markers, we released TYpeSTeR, an easy-to-use script to identify and genotype Y chromosome STRs using population genomic data which can be modulated according to available male reference genomes and genomic data, making it widely applicable across taxa