[Article] 貝氏擬態的動態演化：蟻蜘與其螞蟻被擬態者之分子演化分析

原文標題：Dynamics of the evolution of Batesian mimicry: molecular phylogenetic analysis of ant-mimicking Myrmarachne (Araneae: Salticidae) species and their ant models

[摘要] [原文網址]

Batesian mimicry is seen as an example of evolution by natural selection, with predation as the main driving force. The mimic is under selective pressure to resemble its model, whereas it is disadvantageous for the model to be associated with the palatable mimic. In consequence one might expect there to be an evolutionary arms race, similar to the one involving host–parasite coevolution. In this study, the evolutionary dynamics of a Batesian mimicry system of model ants and ant-mimicking salticids is investigated by comparing the phylogenies of the two groups. Although Batesian mimics are expected to coevolve with their models, we found the phylogenetic patterns of the models and the mimics to be indicative of adaptive radiation by the mimic rather than co-speciation between the mimic and the model. This shows that there is strong selection pressure on Myrmarachne, leading to a high degree of polymorphism. There is also evidence of sympatric speciation in Myrmarachne, the reproductive isolation possibly driven by female mate choice in polymorphic species.

這篇很誇張。

作者感覺野心很大，想要用一個簡單的模型，來測試擬態中的pattern演化是否連動，甚至是共演化的，於是他們選用的是蟻蜘，與當地蟻蜘擬態的螞蟻，方法也很簡單，把蟻蜘的phylogeny做出來，把model螞蟻的phylogeny做出來，然後用tangle tree的方式看有沒跟host-parasite一樣的共演化。

但是整篇都是悲劇，首先是文章中的蟻蜘分類不明，生殖器有多態型變異，體色多態型，所以無法從型態上區分種類，也無從判斷不同的mimic是不是同種，甚至有沒有雜交都很難說，其次蜘蛛要到終齡生殖器才會成熟，文中也提到蟻蜘是個漸進擬態的物種，也是不同齡期體色都會變化，看起來都可能像不同的螞蟻，因此如果抓到非終齡個體，就是悲劇了。分子樹看起來的結果也無法明顯分類，而且樣本數非常少(N=12)。再來他們把不同的螞蟻model，通通拿來做一棵樹，即使這些螞蟻通通都是不同亞科的分類群，只為了要跑tangle tree analysis，想當然這樣做出來的結果不只樹形沒顯著相關，各種演化事件也分布的十分奇怪，但看起來只是個軟體計算的結果。