[Article] 捕食者與共擬態者的視覺，如何形塑具有細微顏色差異穆氏擬態之共擬態者間的斑紋演化？
（圖片選自內文）
原文標題：Cryptic differences in colour among Müllerian mimics: how canthe visual capacities of predators and prey shape the evolution of wing colors?
[摘要] [原文網址]
Antagonistic interactions between predators and prey often lead to co-evolution. In the case of toxic prey, aposematic colours act as warning signals for predators and play a protective role. Evolutionary convergence in colour patterns among toxic prey evolves due to positive density-dependent selection and the benefits of mutual resemblance in spreading the mortality cost of educating predators over a larger prey assemblage. Comimetic species evolve highly similar colour patterns, but such convergence may interfere with intraspecific signalling and recognition in the prey community, especially for species involved in polymorphic mimicry. Using spectrophotometry measures, we investigated the variation in wing coloration among comimetic butterflies from distantly related lineages. We focused on seven morphs of the polymorphic species Heliconius numata and the seven corresponding comimetic species from the genus Melinaea. Significant differences in the yellow, orange and black patches of the wing were detected between genera. Perceptions of these cryptic differences by bird and butterfly observers were then estimated using models of animal vision based on physiological data. Our results showed that the most strikingly perceived differences were obtained for the contrast of yellow against a black background. The capacity to discriminate between comimetic genera based on this colour contrast was also evaluated to be higher for butterflies than for birds, suggesting that this variation in colour, likely undetectable to birds, might be used by butterflies for distinguishing mating partners without losing the benefits of mimicry. The evolution of wing colour in mimetic butterflies might thus be shaped by the opposite selective pressures exerted by predation and species recognition.
在一些之前的研究中，我們已經知道毒蝶的穆氏擬態中，不同類群的斑紋是由不同的基因調控而來（簡單的說就是趨同），那麼理論上不同的物種間的斑紋顏色應該會多少有差異，若是顏色的差異太大的話，就可能脫離擬態群被捕食者攻擊，因此這些顏色的差異是在一個可容忍的「範圍」內的，事實上來說，我們也的確認為這些擬態者的顏色幾乎沒有差異，但若是顏色幾乎沒有差異的話，各物種是如何辨別同或不同種呢？
這篇研究用光譜儀測試了翅面上的黃、橘與黑色，發現在兩個不同屬間，雖然看起來很像，但在亮度、色調與濃度上各有顯著的差異，那麼，如果顏色是有差異的，穆氏擬態或種內辨識是否就會有所衝突？
這從生理學上得到解釋，捕食者的視覺系統無法分辨這麼細微的差異，而蝴蝶的視覺可分辨這些差異，因此「我們」看起來幾乎無差異的顏色，經由天擇的選汰形成擬態群，蝴蝶又可藉由這些差異分辨種類。（註）
註：在早期的研究中，已發現毒蝶可經由視覺選擇與自身斑紋較類似的個體交尾，因此毒蝶是可藉由視覺分辨個體間差異的。
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