[Article] 英國一種食蚜蠅涉入貝氏擬態的證據

photo from http://goo.gl/9CDbHK

原文標題：Evidence for Batesian mimicry in a polymorphic hoverfly

摘要[原文網址]

Palatable Batesian mimics are avoided by predators because they resemble noxious or defended species. The striking resemblance of many hoverflies to noxious Hymenoptera is a “textbook” example of Batesian mimicry, but evidence that selection by predators has shaped the evolution of hoverfly patterns is weak. We looked for geographical and temporal trends in frequencies of morphs of the polymorphic hoverfly Volucella bombylans that would support the hypothesis that these morphs are Batesian mimics of different bumblebee species. The frequency of the black and yellow hoverfly morph was significantly positively related to the frequency of black and yellow bumblebees across 52 sites. Similarly, the frequency of the red-tailed hoverfly morph was positively related to the frequency of red-tailed bumblebees. However, the frequencies of hoverfly morphs were positively spatially autocorrelated, and after controlling for this, only one of the two common hoverfly morphs showed a significant positive relationship with its putative model. We conclude that the distribution of V. bombylans morphs probably reflects geographical variation in selection by predators resulting from differences in the frequencies of noxious bumblebee species.

這三行剛好代表三群不同的類型，最下面的一列表示其model（本圖取自該篇文章）

這篇文章的取樣點調查短則一年，長則六年，採樣點遍及英國中南部。其結果顯示某區域model越多的地方，擬態該物種的食蚜蠅的那個型頻度也會越高，代表不一樣的型都藉由天擇的力量被淘汰掉了（詳細分析請見內文）。

這篇只是一個很簡單的邏輯，但實際上要找到兩個物種間互相擬態的證據是不容易的，而在現在擬態生物學的領域中，也很難單純的只依靠兩個物種的外型就直指其擬態關係，通常也會要求提出相關的證據，簡單的說，就是越來越難做了（嘆）。