TOWARD COMPREHENSIVE UNDERSTANDING OF EVOLUTION OF APOSEMATIC COLORATION

为了全面了解缺失性着色的进化，我们研究了在贝特斯拟态和米勒拟态中观察到的缺失性。Ohsaki研究了拟态和非拟态类型的雌性蝴蝶的生态特性，在这些类型中，Betesian拟态仅限于雌性蝴蝶。在无捕食条件下，模仿型雌鸟的存活率低于非模仿型雌鸟，这表明模仿型雌鸟需要付出很大的适应成本。对热带蝴蝶群落的现场调查显示，雌性蝴蝶的捕食压力比雄性更大，特别是在树冠周围高速飞行的物种，而那些在地面附近低速飞行的物种则没有做到这一点。这些结果可能解释了为什么贝特斯模仿仅限于“快速”蝴蝶的性别，而不是“迟缓”蝴蝶的性别。西田研究了两对焦角类昆虫的苗勒式拟态，其中一对是捕食者，另一对是猎物。体色的反射率在一个系统中非常相似和高，但在另一个系统中不同，这可能与捕食者-捕食者相互作用的专门化程度相对应：前者高度专门化，后者较为普遍。这两个系统中都没有共同的捕食者，这表明至少在目前，穆勒模仿不起作用，这可能需要在自然选择的背景下做出不同的解释。

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.