Ruxton Graeme D, Sherratt Thomas N
Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sceinces, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK.
Proc Biol Sci. 2006 Oct 7;273(1600):2417-24. doi: 10.1098/rspb.2006.3570.
In a seminal contribution, Fisher argued how distastefulness could incrementally evolve in a prey species that was distributed in family groups. Many defended prey species occur in aggregations, but did aggregation facilitate the evolution of defence as Fisher proposed or did the possession of a defence allow individuals to enjoy the benefits of group living? Contemporary theory suggests that it can work both ways: pre-existing defences can make the evolution of gregariousness easier, but gregariousness can also aid the evolution of defence and warning signals. Unfortunately, the key phylogenetic analyses to elucidate the ordering of events have been hampered by the relative rarity of gregarious species, which in itself indicates that aggregation is not a pre-requisite for defence. Like the underlying theory, experimental studies have not given a definitive answer to the relative timing of the evolution of defence and aggregation, except to demonstrate that both orderings are possible. Conspicuous signals are unlikely to have evolved in the absence of a defence and aggregated undefended prey are likely to be vulnerable to predation in the absence of satiation effects. It therefore seems most likely that defence generally preceded the evolution of both aggregation and signalling, but alternative routes may well be possible.
在一项具有开创性的研究中，费希尔论证了厌恶感如何在以家族群体形式分布的猎物物种中逐渐演变。许多有防御能力的猎物物种以群体形式出现，但群体生活是像费希尔所提出的那样促进了防御能力的进化，还是拥有防御能力使个体能够享受群体生活的益处呢？当代理论表明这两种情况都有可能：预先存在的防御能力会使群居习性的进化更容易，但群居习性也有助于防御能力和警告信号的进化。不幸的是，用于阐明事件发生顺序的关键系统发育分析受到群居物种相对稀少的阻碍，这本身就表明群体生活并非防御的先决条件。与基础理论一样，实验研究也没有对防御能力和群体生活进化的相对时间给出明确答案，只是证明两种顺序都是可能的。在没有防御能力的情况下，显眼的信号不太可能进化出来，而在没有饱腹感效应的情况下，无防御能力的群居猎物很可能容易被捕食。因此，防御能力似乎最有可能通常先于群体生活和信号传递的进化，但其他途径也很有可能存在。
