动物行为研究的新进展(九)：亲代抚育行为

以红切叶蜂、埋葬甲、白鹭和鲣鸟为实例，简要地介绍了近年来动物双亲抚育行为的一些研究进展和研究成果，包括双亲抚育行为的利弊分析、双亲偏爱和同胞互残三个方面。亲鸟喂养幼鸟可增加后代的存活机会，但也会遭遇一定的风险，这其中就存在着利弊分析的问题，应当如何进行权衡呢？即使是双亲把抚育完全给自己的幼鸟，也不能做到在子女之间完全均等地分配资源，甚至在父母与子女之间的亲缘系数是0.5的情况下也是如此。白鹭双亲不仅对同胞互残行为不加制止，反而会促使它的发生，这是因为在一窝幼鸟中借助互残行为可自行淘汰那些不太可能存活到生育年龄的个体，这有助于双亲把它们的关爱只传递给那些最有可能发育到生殖年龄传下后代的个体，并使双亲的食物传递损耗降到最低。这是进化和自然选择导致行为最优的又一实例。

New advance on study of animal behavior (IX): parental care

By feeding their youngs, adult birds increase the survival chances of their nestlings. But there are risks attendant upon the parents’feeding trips. How does a parental bird balance the pluses and minuses of its activities? The key to explain the diversity in parental behavior lies to the cost-benefit analysis. Even when parents invest only in their own progeny, they rarely distribute their care in a completely equitable fashion, even when the coefficient of relatedness between parents and all their genetic offspring is the same (0.5 as a result of sexually reproducing parents placing 50 percent of their genes on each egg or sperm). Sibling rivalry and siblicide help parents deliver their care only to offspring that have a good chance of eventually reproducing, while keeping their food delivery costs to a minimum. It is conceivable that siblicide may have evolves only because of the fitness advantages enjoyed by offspring able to dispose of siblings that were competing for the same supply of food.