A comparative analysis of the evolution of imperfect mimicry
A comparative analysis of the evolution of imperfect mimicry
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DOI：
10.1038/nature10961
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发表时间：
2012-03-22
期刊：
影响因子：
64.8
通讯作者：
Sherratt, Thomas N.
中科院分区：
文献类型：
--
作者：
Penney, Heather D.;Hassall, Christopher;Sherratt, Thomas N.
虽然适应的特殊例子经常被庆祝，但自然选择的一些结果似乎远非完美。例如，许多食蚜蝇（双翅目：食蚜蝇科）是无害的（蝙蝠（1）），类似于刺的Hyplettera（2）。然而，尽管一些食蚜蝇物种被认为是优秀的模仿者，但其他物种与它们的模型只有表面上的相似之处，目前还不清楚为什么会这样。为了评估已经提出的假设，以解释古北食蚜蝇科的拟态保真度种间变异，我们使用比较的方法。我们发现，最合理的解释是，捕食者施加较少的选择模仿保真度较小的食蚜蝇物种，因为他们是利润较低的猎物项目。特别是，我们的发现，结合以前的结果，使我们能够拒绝几个关键的假设不完美的模仿：首先，人类的模仿保真度的评级与形态测量和鸟类排名呈正相关，表明模仿保真度的变化不仅仅是基于人类感知的错觉（4）;第二，没有一个种类的蚜虫在多维空间中表现为介于几个不同的hyperteran模式种之间，正如多模式假说（5）所要求的那样;第三，我们没有发现证据表明模仿的忠实度和丰富度之间存在负相关关系，这对亲属选择假说提出了质疑。相比之下，模仿的保真度和身体大小之间的强正相关支持放松选择假说（7，8），这表明减少捕食压力对利润较低的猎物物种限制了模仿完美的选择。
Although exceptional examples of adaptation are frequently celebrated, some outcomes of natural selection seem far from perfect. For example, many hoverflies (Diptera: Syrphidae) are harmless (Batesian(1)) mimics of stinging Hymenoptera(2). However, although some hoverfly species are considered excellent mimics, other species bear only a superficial resemblance to their models(3) and it is unclear why this is so. To evaluate hypotheses that have been put forward to explain interspecific variation in the mimetic fidelity of Palearctic Syrphidae we use a comparative approach. We show that the most plausible explanation is that predators impose less selection for mimetic fidelity on smaller hoverfly species because they are less profitable prey items. In particular, our findings, in combination with previous results, allow us to reject several key hypotheses for imperfect mimicry: first, human ratings of mimetic fidelity are positively correlated with both morphometric measures and avian rankings, indicating that variation in mimetic fidelity is not simply an illusion based on human perception(4); second, no species of syrphid maps out in multidimensional space as being intermediate in appearance between several different hymenopteran model species, as the multimodel hypothesis(5) requires; and third, we find no evidence for a negative relationship between mimetic fidelity and abundance, which calls into question the kin-selection(6) hypothesis. By contrast, a strong positive relationship between mimetic fidelity and body size supports the relaxed-selection hypothesis(7,8), suggesting that reduced predation pressure on less profitable prey species limits the selection for mimetic perfection.