photo from http://www.qwiki.com/q/#!/Peppered_moth
原文標題：Mimicking multiple models: polyphenetic masqueraders gain additional benefits from crypsis
Many prey organisms avoid predation by mimicking inanimate objects: a phenomenon known as masquerade. It is expected that masquerade will show a frequency-dependent advantage such that masquerading species benefit more from their appearance when they are rare in comparison with their models. In such circumstances, selection may favor the coexistence of different phenotypes (polyphenism or polymorphism). The American peppered moth caterpillar Biston betularia cognataria appears to show polyphenetic masquerade: caterpillars found on birch trees look like birch twigs; those on willow trees look like willow twigs. Here, we show in laboratory experiments that the caterpillar does benefit from masquerade and that polyphenism is key to this benefit: avian predators misclassified birch-fed larvae as birch twigs and willow-fed larvae as willow twigs. In a second experiment where the benefits of masquerade were excluded, we show that larvae are less likely to be attacked when located on the host species whose twigs they resemble than when found on an alternative species whose twigs they do not resemble; thus, the polyphenism provides antipredatory benefits through crypsis as well as through masquerade. This is the first time that a species has been demonstrated to have the capacity to benefit both from masquerade and from crypsis, and the first time, polyphenism has been demonstrated to benefit masquerade.
這篇是由J. Skelhorn與G. Ruxton所寫的文章，文中的出發點很有趣，他們利用北美的胡椒蛾(Biston betularia congataria)的幼蟲做為實驗材料，這個幼蟲有兩型，在樺木上就會像樺木的枝條，而在柳樹上就會像柳樹的枝條，而他們認為這樣在不同的枝條呈現不同的型的隱蔽(crypsis)是一種擬態，而這邊擬態的角色則是樹（註）。
這組人馬同樣用小雞進行實驗，實驗分成兩部分，第一個部分測試鳥類是否會把幼蟲當成枝條，也就是「幼蟲像不像枝條」這件事，實驗結果支持這個理論，但即使這樣，他們還是無法下定論，因為鳥類不攻擊幼蟲也有可能是因為幼蟲本身的隱蔽色而不是因為這樣的擬態，因此他們做了第二部分的實驗，測試幼蟲在枝條上的擬態是否成立，捕食者可能藉由這樣的擬態降低發現幼蟲的機率，而幼蟲成功逃避捕食者的攻擊，實驗結果也支持幼蟲在相似的枝條上的擬態效果是較成功的。
在之前有關擬態的實驗中，其實比較少談到關於多態型，或是擬態多個model之類的文章，可能是因為那些典型的例子比較少出現這樣的狀況，然而近幾年研究擬態的相關學者逐漸發現，多態型與擬態多個model可能比想像中的更常見，而且難以解釋這樣的關係，而這關係通常又牽扯完美與不完美擬態（典型例子中大多認為是完美擬態），因此從兩三年前一篇nature的文章談到multiple model之後，逐漸有文章開始討論這方面的議題，而這是第一篇正式測試多態型(polymorphism)與非遺傳多型性(polyphenism)對於擬態效應的文章，雖然不在討論防禦性擬態，但提供了一些多態型與擬態間的證據。
註：有些學者認為這樣的偽裝(camouflage) 是一種自我擬態(automimicry)，而也有看法認為關係必須局限於物種內才能算是自我擬態，如眼斑這樣的例子。本篇所採用的「擬態」的看法似乎是認為這可能算某種擬態，但在定義上這應該算是偽裝，因此本篇可能採用自我擬態的看法，但個人認為這仍有爭議。
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