Female counter-strategies to male infanticide in primates

灵长类动物群居，两性之间的社会关系差异很大。这些关系受到雄性繁殖竞争和雌性择偶的影响。雄性有时会对雌性进行性胁迫以获得交配机会，而雄性性胁迫的一种极端表现是雄性杀婴。杀婴的雄性如果杀死没有血缘关系的幼崽，并且比等到断奶后再给雌性授精更早，就会在生殖方面受益。在很多灵长类动物中都观察到雄性杀婴行为，但现在很明显，并不是所有容易被杀婴的个体都被杀死。这表明并不是所有的雄性都杀婴，或者存在成功的雄性和雌性对抗雄性杀婴的策略。杀婴行为对生下受害者的雄性来说代价高昂，但对雌性哺乳动物来说代价更大，因为雌性哺乳动物的潜在繁殖能力更有限。因此，我们应该期望自然选择有利于女性对杀婴行为的反策略的表达。我将研究女性行为的表达，这些行为可以作为杀婴行为的反策略，在这些女性经历的杀婴风险不同的情况下。居民男性对父亲身份的确定程度与其所在群体中母亲的杀婴风险水平呈负相关。在我们研究的灵长类动物中，杀婴率很高，但在所有社会条件下，杀婴的风险并不是平均分布的。生活在单雄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父权确定性。生活在稳定的多雄性群体中的雌性面临中等程度的杀婴威胁，因为这些群体中的雄性个体比单雄性群体中的雄性个体具有更低的父权确定性。在被接管后，杀婴的风险是最严重的，因为新到达的雄性几乎没有确定的父亲身份。我将研究是否有资格作为反杀婴策略的行为表达（与男性保护者联系，增加性接受度，与多个男性交配，快速断奶）与杀婴风险水平共同变化，以及它们是否影响婴儿生存和女性生殖成功。

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.