Department of Zoology, University Avenue, University of Cape Town, Cape Town, South Africa.
Biol Lett. 2010 Feb 23;6(1):48-50. doi: 10.1098/rsbl.2009.0628. Epub 2009 Sep 30.
Many animals respond to predation risk by forming groups. Evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. However, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator-prey systems. To solve this, we manipulated the domains of danger of Cape fur seal (Arctocephalus pusillus pusillus) decoys to provide evidence that a selfish reduction in a seals' domain of danger results in a proportional reduction in its predation risk from ambush shark attacks. This behaviour confers a survival advantage to individual seals within a group and explains the evolution of selfish herds in a prey species. These findings empirically elevate Hamilton's selfish herd hypothesis to more than a 'theoretical curiosity'.
许多动物通过形成群体来应对捕食风险。对于以前没有成群结队但松散相关的猎物来说，群体形成的进化解释通常引发了自私羊群假说。然而，尽管在各种分类群中进行了超过 600 项研究，但由于现实的捕食者-猎物系统中存在几个混淆问题，该假设的关键假设仍然没有得到集体检验。为了解决这个问题，我们操纵了海角海豹（Arctocephalus pusillus pusillus）诱饵的危险域，以提供证据表明海豹的危险域的自私减少会导致其来自伏击鲨鱼攻击的捕食风险成比例减少。这种行为赋予了群体中个体海豹的生存优势，并解释了猎物物种中自私羊群的进化。这些发现从经验上提升了汉密尔顿的自私羊群假说，使其不仅仅是一个“理论上的好奇心”。
