Kempenaers B, Lanctot RB, Robertson RJ
Department of Biology, Queen's University
Anim Behav. 1998 Apr;55(4):845-60. doi: 10.1006/anbe.1997.0667.
Extra-pair paternity is common in many socially monogamous passerine birds with biparental care. Thus, males often invest in offspring to which they are not related. Models of optimal parental investment predict that, under certain assumptions, males should lower their investment in response to reduced certainty of paternity. We attempted to reduce certainty of paternity experimentally in two species, the eastern bluebird, Sialia sialis, and the tree swallow, Tachycineta bicolor, by temporarily removing fertile females on two mornings during egg laying. In both species, experimental males usually attempted to copulate with the female immediately after her reappearance, suggesting that they experienced the absence of their mate as a threat to their paternity. Experimental males copulated at a significantly higher rate than control males. However, contrary to the prediction of the model, experimental males did not invest less than control males in their offspring. There was no difference between experimental and control nests in the proportion of male feeds, male and female feeding rates, nestling growth and nestling condition and size at age 14 days. We argue that females might have restored the males' confidence in paternity after the experiment by soliciting or accepting copulations. Alternatively, males may not reduce their effort, because the fitness costs to their own offspring may outweigh the benefits for the males, at least in populations where females cannot fully compensate for reduced male investment. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.
在许多实行社会性一夫一妻制且双亲共同育雏的雀形目鸟类中，配偶外父权现象很常见。因此，雄性常常会对与其没有亲缘关系的后代进行投资。最优亲代投资模型预测，在某些假设条件下，雄性应根据父权确定性的降低而减少投资。我们试图通过在产卵期的两个早晨暂时移走可育雌鸟，来实验性地降低东部蓝鸲（Sialia sialis）和双色树燕（Tachycineta bicolor）这两个物种的父权确定性。在这两个物种中，实验雄鸟通常会在雌鸟重新出现后立即试图与其交配，这表明它们将配偶的缺失视为对其亲权的一种威胁。实验雄鸟的交配频率显著高于对照雄鸟。然而，与模型预测相反的是，实验雄鸟对其后代的投资并不比对照雄鸟少。在雄鸟喂食比例、雄雌喂食率、雏鸟生长情况以及14日龄雏鸟的状况和体型方面，实验巢和对照巢之间没有差异。我们认为，实验结束后，雌鸟可能通过主动求偶或接受交配恢复了雄鸟对父权的信心。或者，雄鸟可能不会减少努力，因为对其自身后代的适合度成本可能超过对雄鸟的益处，至少在雌鸟无法完全弥补雄鸟投资减少的种群中是这样。版权所有1998动物行为研究协会。版权所有1998动物行为研究协会。
