Department of Zoology, Downing Street, Cambridge CB2 3EJ, UK.
Proc Biol Sci. 2011 Sep 7;278(1718):2638-45. doi: 10.1098/rspb.2010.2594. Epub 2011 Jan 26.
How sensitive should parents be to the demands of their young? Offspring are under selection to seek more investment than is optimal for parents to supply, which makes parents vulnerable to losing future fitness by responding to manipulative displays. Yet, parents cannot afford to ignore begging and risk allocating resources inefficiently. Here, we show that parents may solve this problem by adjusting their sensitivity to begging behaviour in relation to their own likelihood of breeding again, a factor largely neglected in previous analyses of parent-offspring interactions. In two carotenoid-supplementation experiments on a New Zealand passerine, the hihi Notiomystis cincta, we supplemented adults to enhance their propensity to breed again, and supplemented entire broods to increase their mouth colour, thus enhancing their solicitation display. We found that adults that attempted two breeding attempts a season were largely insensitive to the experimentally carotenoid-rich gapes of their brood, whereas those that bred just once responded by increasing their rate of provisioning at the nest. Our results show that parents can strategically vary their sensitivity to begging in relation to their future reproductive potential. By restricting opportunities for offspring to influence provisioning decisions, parents greatly limit the potential for offspring to win parent-offspring conflict.
父母应该对子女的需求有多敏感？后代在寻求比父母提供的最佳投资更多的投资，这使得父母容易因回应操纵性的表现而失去未来的适应能力。然而，父母不能忽视乞求，也不能冒险低效地分配资源。在这里，我们表明，父母可以通过调整他们对乞求行为的敏感性来解决这个问题，这种敏感性与他们再次繁殖的可能性有关，这是以前对亲子互动分析中很大程度上被忽视的一个因素。在对新西兰雀形目鸟类 hihi Notiomystis cincta 的两项类胡萝卜素补充实验中，我们对成年个体进行补充，以增强其再次繁殖的倾向，并对整个雏鸟进行补充，以增加其嘴部颜色，从而增强其乞讨表现。我们发现，那些一个季节尝试两次繁殖的成年个体对其雏鸟表现出的实验性富含类胡萝卜素的张口行为基本不敏感，而那些只繁殖一次的个体则通过增加巢内的喂养频率来做出反应。我们的研究结果表明，父母可以根据其未来的繁殖潜力，有策略地调整对乞求的敏感性。通过限制后代影响喂养决策的机会，父母极大地限制了后代赢得亲子冲突的潜力。
