Sherratt Thomas N
School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK.
Proc Biol Sci. 2002 Apr 7;269(1492):741-6. doi: 10.1098/rspb.2001.1944.
It has long been recognized that defended prey tend to be conspicuous. Current theories suggest that the association ('aposematism') has arisen because predators more readily learn to avoid attacking defended phenotypes when they are conspicuous. In this paper, I consider why such psychology has evolved. In particular, I argue that aposematism may have evolved not because of an independent and pre-existing receiver bias, but because the conspicuousness of a prey item provides a reliable indicator of its likelihood of being defended. To develop my case I consider how warning signals might coevolve in a system containing a number of predators, whose foraging behaviour is also subject to selection. In these cases, models readily show that the greater the conspicuousness of a novel prey item, the more likely that it has been encountered by other predators and survived. As a consequence, naive predators should be less likely to attack highly conspicuous novel prey on encounter, or at least more inclined to attack them cautiously. This adaptive predator behaviour will greatly facilitate the spread of aposematic phenotypes from extreme rarity, which in turn will enhance selection for forms of predator behaviour under which aposematism will coevolve even more readily.
长期以来，人们一直认识到具有防御能力的猎物往往很显眼。当前的理论认为，这种关联（“警戒色”）的出现是因为当具有防御能力的表型显眼时，捕食者更容易学会避免攻击它们。在本文中，我思考了这种心理为何会进化。具体而言，我认为警戒色的进化可能并非由于独立且预先存在的接收者偏差，而是因为猎物的显眼性提供了其具有防御能力可能性的可靠指标。为了阐述我的观点，我考虑了在一个包含多种捕食者的系统中，警告信号可能如何共同进化，这些捕食者的觅食行为也会受到选择的影响。在这些情况下，模型很容易表明，一种新猎物越显眼，就越有可能被其他捕食者遇到并存活下来。因此，初次遇到新猎物时，天真的捕食者应该不太可能攻击高度显眼的新猎物，或者至少更倾向于谨慎地攻击它们。这种适应性的捕食者行为将极大地促进警戒色表型从极其罕见的状态传播开来，这反过来又会增强对捕食者行为形式的选择，在这种行为形式下，警戒色将更容易共同进化。
