Merilaita S, Lyytinen A, Mappes J
Department of Biological and Environmental Science, University of Jyväskylä, POBox 35, FIN-40351 Jyväskylä, Finland.
Proc Biol Sci. 2001 Sep 22;268(1479):1925-9. doi: 10.1098/rspb.2001.1747.
We studied selection by predators for cryptic prey coloration in a visually heterogeneous habitat that consists of two microhabitats. It has been suggested that the probability of escaping detection in such habitats might be optimized by maximizing crypsis in one of the microhabitats. However, a recent model indicates that a coloration that compromises the requirements of different microhabitats might sometimes be the optimal solution. To experimentally study these hypotheses, we allowed great tits (Parus major L.) to search for artificial prey items in two different microhabitats (background boards): small patterned and large patterned. On each board there was one prey item that was either small-patterned, large-patterned or medium-patterned and thus compromised. Search time was used as the measure of crypsis and was on average longer on the large-patterned than on the small-patterned background. On the small-patterned background, the small-patterned prey was more cryptic than the compromised prey, which was in turn more cryptic than the large-patterned prey. On the large-patterned background, the small-patterned prey was least cryptic, but the compromised prey did not differ significantly from the large-patterned prey. The compromised coloration had lower predation risk than the matching colorations. This indicates that in some conditions a compromised coloration might be the best strategy for the prey and has important implications for the study of animal coloration.
我们在一个由两种微生境组成的视觉上异质的栖息地中，研究了捕食者对隐蔽性猎物颜色的选择。有人提出，在这样的栖息地中，通过在其中一个微生境中最大化拟态，可能会优化逃脱被发现的概率。然而，最近的一个模型表明，一种折衷不同微生境要求的颜色有时可能是最优解决方案。为了通过实验研究这些假设，我们让大山雀（Parus major L.）在两种不同的微生境（背景板）中寻找人工猎物。在每个板上有一个猎物，它要么是小图案的、大图案的，要么是折衷图案的。搜索时间被用作拟态的衡量标准，在大图案背景上平均比在小图案背景上更长。在小图案背景上，小图案猎物比折衷猎物更隐蔽，而折衷猎物又比大图案猎物更隐蔽。在大图案背景上，小图案猎物最不隐蔽，但折衷猎物与大图案猎物没有显著差异。折衷颜色的捕食风险比匹配颜色的捕食风险更低。这表明在某些情况下，折衷颜色可能是猎物的最佳策略，并且对动物颜色的研究具有重要意义。
