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International audience; Mechanistic models suggest that individuals' memories could shape home range patterns and dynamics, and how neighbours share space. In social species, such dynamics of home range overlap may be affected by the pre-dispersal memories of immigrants. We tested this "immigrant knowledge hypothesis" in a wild population of chacma baboons (Papio ursinus). We predicted that overlap dynamics with a given neighbouring troop's home range should reflect males' adaptive interests in overlap when the alpha male had immigrated from this neighbouring troop but less so when the alpha male originated from elsewhere. We used data collected between 2005 and 2013 on two neighbouring troops in Namibia, comprising GPS records of daily ranges, male natal origins, daily females' reproductive status, and a satellite index of vegetation growth. We found support for our prediction in line with male reproductive strategies but not in line with foraging conditions. In periods with a higher relative number of fertile females over adult males in the focal troop, male baboons would benefit from reducing overlap with their neighbours to mitigate the costs of between-troop mating competition. This was indeed observed but only when the alpha male of the focal troop was an immigrant from that neighbouring troop, and not with alpha males of other origins, presumably due to their different knowledge of the neighbouring troop. Our findings highlight the role of reproductive competition in the range dynamics of social groups, and suggest that spatial segregation between groups could increase through the combination of dispersal and memory.

International audience

International audience

Investigating how individuals adjust their investment into distinct components of the immune system under natural conditions necessitates to develop immune phenotyping tools that reflect the activation of specific immune components that can be measured directly in the field. Here, we examined individual variation of plasma neopterin, a biomarker of Th1 immunity in wild mandrills (Mandrillus sphinx), who are naturally exposed to a suite of parasites, including simian retroviruses and malaria agents. We analyzed a total of 201 plasma samples from 99 individuals and examined the effect of sex, age, social rank, reproductive state and disease status on neopterin levels. We found higher neopterin concentrations in males than females, but were unable to disentangle this effect from possible confounding effects of retroviral infections, which affect nearly all adult males, but hardly any females. We further detected a non-linear age effect with heightened neopterin levels in early and late life. In addition, adult males that harbored very high parasitaemia for Plasmodium gonderi also showed high neopterin levels. There was no effect of social rank in either male or female mandrills, and no effect of female reproductive state. Taken together, these results indicate that plasma neopterin may prove useful to investigate individual variation in investment into specific immune components, as well as to monitor the dynamics of immune responses to naturally occurring diseases that elicit a Th1 immune response., Graphical abstract Image 1, Highlights • We measured plasma neopterin, a promising immune marker, in wild mandrills. • We found a U-shaped age effect, with high neopterin levels in early and late life. • Adult males had more neopterin than females, possibly due to retroviruses. • Adult males with high Plasmodium gonderi parasitaemia had high neopterin levels. • Neopterin can help monitoring Th1 immunity and immunosenescence in primates.

All drawings were downloaded from PhyloPic: http://phylopic.org; this file credits the specific authors

Female–female competition over paternal care has rarely been investigated in promiscuous mammals, where discreet forms of male care have recently been reported despite low paternity certainty. We investigated female competition over paternal care in a wild promiscuous primate, the chacma baboon (Papio ursinus), where pregnant and lactating females establish strong social bonds (friendships) with males that provide care to their offspring. We tested whether pregnant and lactating females interfere with the sexual activity of their male friend to prevent new conceptions that might lead to the subsequent dilution of his paternal care. We found that pregnant and lactating females were more aggressive towards oestrous females when they had recently conceived themselves, and when the oestrous female was mate-guarded by, and showed greater sexual activity with, their male friend. This aggression also reduced the likelihood of conception of the targeted female. These findings indicate that females can aggressively prevent further conceptions with their offspring's carer through reproductive suppression. Competition over access to paternal care may play an important and underestimated role in shaping female social relationships and reproductive strategies in promiscuous mammalian societies.

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.