Female counter-strategies to male infanticide in primates

灵长类动物成群结队地生活，表现出两性之间社会关系的巨大差异。这些关系受到男性生殖竞争和女性配偶选择的影响。男性有时会利用男性对女性的性胁迫来获得交配机会，而男性性胁迫的一个极端表现就是男性杀害婴儿。杀婴的雄性如果杀死无关的婴儿，并且比不得不等到断奶时更早给雌性授精，就会受益于生殖。在广泛的灵长类动物中观察到了杀害男婴的现象，但现在很明显，并不是所有容易被杀婴的人都会被杀死。这表明并不是所有的男性都是杀婴的，和/或存在成功的男性和女性对抗杀婴的策略。杀婴对于繁殖受害者的雄性来说代价高昂，但对于雌性哺乳动物来说代价更高，因为它们的潜在生殖产出更有限。因此，人们应该期待自然选择有利于表达女性对杀婴的反策略。我将调查女性行为的表现，这些行为可以被视为反杀婴策略，在这些女性经历的杀婴风险不同的情况下。居民男性(S)的亲子确定程度与其群体中母亲经历的杀婴风险水平呈负相关。杀婴率很高是我们研究的灵长类种群，但杀婴的风险并不是在所有社会条件下平均分布的。生活在单一男性群体中的女性面临的杀婴风险最小，因为这些群体中的男性具有很高的亲子关系确定性。生活在稳定的多男性群体中的女性面临中等水平的杀婴威胁，因为这些群体中的男性个体比单一男性群体中的男性亲子鉴定确定性更低。在接管之后，杀婴的风险最大，因为新来的雄性几乎没有亲子关系。我将研究符合反杀婴策略的行为的表达(与男性保护者相关，性接受性增加，与多个男性交配，以及快速断奶)是否与杀婴风险水平存在协同变化，以及它们是否影响婴儿存活和女性生殖成功。

Primates live in groups that show great variation in social relationships between the sexes. These relationships are influenced by male reproductive competition and female mate choice. Males sometimes use male sexual coercion of females to attain mating opportunities, and one extreme expression of male sexual coercion is infanticide by males. Infanticidal males benefit reproductively if they kill unrelated infants and they inseminate a female sooner than if they had to wait until weaning. Male infanticide has been observed in a wide range of primates, but it is now apparent that not all individuals vulnerable to infanticide are killed. This suggests that not all males are infanticidal, and/or the existence of successful male and female counter-strategies to male infanticide. Infanticide is costly for the males who sired the victims, but is even more costly for female mammals, that are more limited in their potential reproductive output. One should thus expect natural selection to favor the expression of female counter-strategies to infanticide. I will investigate the expression of female behaviors that could qualify as counter-strategies to infanticide, in situations where the infanticide risk that these females experience varies. The level of paternity certainty that resident male(s) have is inversely related to the level of infanticide risk experienced by the mothers in their group. Infanticide rate is high is the population of primates that we study, but the risk of infanticide is not distributed equally across all social conditions. Females living in uni-male groups face the least infanticide risk, as males in these groups have high paternity certainty. Females living in stable multi-male groups face a moderate level of infanticide threat, as individual males in these groups have lower paternity certainty than in uni-male groups. The risk of infanticide is most acute immediately after a takeover, as the newly-arrived males have a close-to-zero paternity certainty. I will examine if the expression of behaviors that qualify as counter-strategies against infanticide (association with a male protector, increased sexual receptivity, mating with multiple males, and rapid weaning) co-vary with the level of infanticide risk, and if they influence infant survival and female reproductive success.