Counter-Strategies against Infanticide by Males in Primates

雄性杀婴，即成年雄性瞄准、攻击和杀死脆弱的婴儿，在许多哺乳动物中都有发生，一项重要的研究调查了这些雄性如何从杀死婴儿中获利。然而，对于其他三个个体——母亲、婴儿和父亲——来说，杀婴的代价是高昂的，而且人们对他们如何应对杀婴的风险知之甚少。我之前曾研究过一种野生灵长类动物（黑白疣猴），雌性用来抵抗或应对杀婴风险的策略。高杀婴风险对婴儿和父亲的影响，以及他们如何制定策略来抵制杀婴行为，受到的研究关注要少得多。我的目标是继续测试与雌性雄性杀婴策略相关的假设，并将调查扩展到包括测试与相同野生疣猴种群的婴儿和父亲的成本和采取的对抗策略相关的假设。该种群人口密度高，雄性交配竞争激烈，雄性杀婴现象时有发生。个体经历不同程度的杀婴风险取决于他们所生活的群体，因为常住男性的父权概率从单雄性、一夫多妻群体（高父权概率）、稳定的多雄性、一夫多妻群体（中等父权概率）到最近发生接管和新常住男性在受孕期间没有与女性交配的群体（低父权概率）各不相同。这些条件（高人口密度，高雄性交配竞争，不同社会群体的杀婴风险不同）创造了一个理想的环境，可以收集必要的数据来检验研究假设。我和我的学生将进行一系列研究来检验以下假设：在杀婴风险高的情况下，母亲会突然断奶，并与几个雄性交配以扩大父权的可能性；在杀婴风险较高的情况下，婴儿发育将会加快，而这种加快的婴儿发育将转化为更早的营养独立；父亲对婴儿的容忍度会受到父亲身份的影响，并与杀婴风险水平共变。人们已经进行了大量的研究，以了解雄性杀婴行为发生的条件，以及了解杀婴雄性如何从这种行为的表达中获益。这项研究有助于我们理解这场进化军备竞赛的另一面，评估母亲、婴儿和父亲（对他们来说，杀婴是代价高昂的）用来应对杀婴威胁的策略。

Infanticide by males, where adult males target, attack and kill vulnerable infants, occurs in a wide range of mammals, and an important body of research investigates how these males gain from killing infants. Male infanticide is costly, however, for three other individuals - the mother, the infant and the father and much less is known about how they cope with the risk of infanticide. I have previously investigated the tactics used by females to resist or cope with infanticide risk in a wild primate species (the black and white colobus). The impact of high infanticide risk on infants and fathers, and how they might develop tactics to resist infanticide, has received much less research attention. My objective is to continue to test hypotheses related to female counterstrategies infanticide by males, and to extend the investigation to include the testing of hypotheses related to the costs to, and counter-strategies employed by, infants and fathers, with the same population of wild colobus monkeys. This population has high population density and intense male mating competition, and infanticide by males occurs regularly. Individuals experience varying levels of infanticide risk depending on the group in which they live, since paternity probability for resident male(s) varies from uni-male, polygynous groups (high paternity probability), stable multi-male, polygynandrous groups (moderate level of paternity probability) to groups where a recent takeover occurred and where the new resident male(s) did not mate with the females around the time of conception (low paternity probability). These conditions (high population density, high male mating competition, varying infanticide risk depending on the social groups) create an ideal situation in which to collect the data necessary to test the research hypotheses. My students and I will conduct a number of studies to test the following hypotheses: Under high infanticide risk conditions, mothers will wean their infant abruptly, and will mate with several males to spread paternity probabilities; still under high infanticide risk conditions, infant development will be accelerated and this faster infant development will translate into earlier nutritional independence; and fathers' tolerance of infants will be influenced by paternity and will co-vary with the level of infanticide risk. Considerable research has been conducted to understand the conditions under which male infanticide occurs, as well as to understand how infanticidal males might gain from the expression of this behaviour. This study contributes to our understanding of the other side of this evolutionary arms race, in assessing the strategies used by mothers, infants and fathers - for whom male infanticide is costly - to cope with the threat of male infanticide.