TOWARD COMPREHENSIVE UNDERSTANDING OF EVOLUTION OF APOSEMATIC COLORATION

为了全面了解警戒色的演变，我们研究了在Behran拟态和Mullerian拟态中观察到的警戒色。Ohsaki研究了拟态和非拟态类型的雌性蝴蝶的生态特性，其中Bearing拟态仅限于雌性。在无捕食条件下，拟态雌性的存活率低于非拟态雌性，表明拟态的适应度成本很大。对热带蝴蝶群落的实地调查显示，雌性的捕食压力大于雄性，尤其是在树冠周围高速飞行的物种，但在地面附近低速飞行的物种没有这样做。这些结果可以解释为什么在“快速”蝴蝶中，拟雌蝶是有性别限制的，而在“缓慢”蝴蝶中则不然。Nishida研究了两对Pyrrhocorid错误的Mullerian拟态，其中一个是捕食者，另一个是猎物。体色反射率在一个系统中非常相似且高，但在另一个系统中不同，这可能对应于捕食者-被捕食者相互作用的专门化程度：在前者中高度专门化，而在后者中相当普遍。在这两个系统中缺乏共同的捕食者表明，至少在目前，穆勒模仿没有工作，这可能需要在自然选择的背景下替代解释。

To understand the evolution of aposematic coloration comprehensively, we examined aposematism observed both in Betesian mimicry and Mullerian mimicry. Ohsaki examined ecological properties of mimetic and non-mimetic types of female butterflies in which Betesian mimicry is specific only to females. Under predation free conditions the mimetic females had lower survival rate than did non-mimetic females, suggesting a large fitness cost of being mimetic. Filed census on tropical butterfly community revealed greater predation pressure for females than for males particularly for species that fly at a high speed around tree canopies, but failed to do so for those flying at a lowspeed near the ground. These results may explain why Betesian mimicry is sex limited in "speedy" butterflies but not so in "sluggish" butterflies. Nishida examined Mullerian mimicry in two pairs of pyrrhocorid bugs, in both of which one was a predator and the other was a prey. Reflectance of body coloration was quite similar and high in one system, but different in the other system, which may corresponded to the degree of specialization over prey-predator interaction: highly specialized in the former and rather generalized in the latter. Absence of common predators in both systems suggested that at least at present, Mullerian mimicry did not work, which may require alternative explanations in the context of natural selection.