Jindal Shagun, Bose Aneesh P H, O'Connor Constance M, Balshine Sigal
Aquatic Behavioural Ecology Laboratory, Department of Psychology, Neuroscience, and Behaviour , McMaster University , 1280 Main Street West, Hamilton, Ontario Canada L8S 4K1.
R Soc Open Sci. 2017 Mar 8;4(3):160891. doi: 10.1098/rsos.160891. eCollection 2017 Mar.
Infanticide and offspring cannibalism are taxonomically widespread phenomena. In some group-living species, a new dominant individual taking over a group can benefit from infanticide if doing so induces potential mates to become reproductively available sooner. Despite widespread observations of infanticide (i.e. egg cannibalism) among fishes, no study has investigated whether egg cannibalism occurs in fishes as a result of group takeovers, or how this type of cannibalism might be adaptive. Using the cooperatively breeding cichlid, , we tested whether new unrelated males entering the dominant position in a social group were more likely to cannibalize eggs, and whether such cannibalism would shorten the interval until the female's next spawning. Females spawned again sooner if their broods were removed than if they were cared for. Egg cannibalism occurred frequently after a group takeover event, and was rarer if the original male remained with the group. While dominant breeder females were initially highly aggressive towards newcomer males that took over the group, the degree of resistance depended on relative body size differences between the new pair and, ultimately, female aggression did not prevent egg cannibalism. Egg cannibalism, however, did not shorten the duration until subsequent spawning, or increase fecundity during subsequent breeding in our laboratory setting. Our results show that infanticide as mediated through group takeovers is a taxonomically widespread behaviour.
杀婴和同类相食在分类学上是广泛存在的现象。在一些群居物种中，如果新的优势个体接管一个群体时实施杀婴行为能促使潜在配偶更快进入繁殖状态，那么这样做对其是有益的。尽管在鱼类中广泛观察到杀婴行为（即卵食同类现象），但尚无研究调查卵食同类现象在鱼类中是否因群体接管而发生，或者这种同类相食行为可能如何具有适应性。我们以合作繁殖的丽鱼科鱼类为研究对象，测试进入社会群体主导地位的新的无亲缘关系雄性是否更有可能吞食鱼卵，以及这种同类相食行为是否会缩短雌性下次产卵的间隔时间。如果雌性的鱼卵被移除，它们会比受到照料时更快再次产卵。在群体接管事件后，卵食同类现象频繁发生，而如果原来的雄性仍留在群体中则较为罕见。虽然占主导地位的繁殖雌性最初对接管群体的新来雄性极具攻击性，但抵抗程度取决于新配对个体之间的相对体型差异，最终，雌性的攻击性并不能阻止卵食同类行为。然而，在我们的实验室环境中，卵食同类行为并没有缩短直至后续产卵的时长，也没有增加后续繁殖期间的繁殖力。我们的研究结果表明，通过群体接管介导的杀婴行为是一种在分类学上广泛存在的行为。
