Rosser Neil, Kozak Krzysztof M, Phillimore Albert B, Mallet James
Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK.
Present address: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
BMC Evol Biol. 2015 Jun 30;15:125. doi: 10.1186/s12862-015-0420-3.
Sympatric speciation is today generally viewed as plausible, and some well-supported examples exist, but its relative contribution to biodiversity remains to be established. We here quantify geographic overlap of sister species of heliconiine butterflies, and use age-range correlations and spatial simulations of the geography of speciation to infer the frequency of sympatric speciation. We also test whether shifts in mimetic wing colour pattern, host plant use and climate niche play a role in speciation, and whether such shifts are associated with sympatry.
Approximately a third of all heliconiine sister species pairs exhibit near complete range overlap, and analyses of the observed patterns of range overlap suggest that sympatric speciation contributes 32%-95% of speciation events. Müllerian mimicry colour patterns and host plant choice are highly labile traits that seem to be associated with speciation, but we find no association between shifts in these traits and range overlap. In contrast, climatic niches of sister species are more conserved.
Unlike birds and mammals, sister species of heliconiines are often sympatric and our inferences using the most recent comparative methods suggest that sympatric speciation is common. However, if sister species spread rapidly into sympatry (e.g. due to their similar climatic niches), then assumptions underlying our methods would be violated. Furthermore, although we find some evidence for the role of ecology in speciation, ecological shifts did not show the associations with range overlap expected under sympatric speciation. We delimit species of heliconiines in three different ways, based on "strict and " "relaxed" biological species concepts (BSC), as well as on a surrogate for the widely-used "diagnostic" version of the phylogenetic species concept (PSC). We show that one reason why more sympatric speciation is inferred in heliconiines than in birds may be due to a different culture of species delimitation in the two groups. To establish whether heliconiines are exceptional will require biogeographic comparative studies for a wider range of animal taxa including many more invertebrates.
如今，同域物种形成通常被认为是合理的，并且存在一些有充分证据支持的例子，但其对生物多样性的相对贡献仍有待确定。我们在此量化了赫氏凤蝶姐妹物种的地理重叠情况，并利用年龄范围相关性以及物种形成地理的空间模拟来推断同域物种形成的频率。我们还测试了模拟翅色模式、寄主植物利用和气候生态位的变化在物种形成中是否起作用，以及这些变化是否与同域分布相关。
所有赫氏凤蝶姐妹物种对中约有三分之一表现出近乎完全的分布范围重叠，对观察到的分布范围重叠模式的分析表明，同域物种形成占物种形成事件的32% - 95%。缪勒拟态颜色模式和寄主植物选择是高度不稳定的性状，似乎与物种形成有关，但我们发现这些性状的变化与分布范围重叠之间没有关联。相比之下，姐妹物种的气候生态位更为保守。
与鸟类和哺乳动物不同，赫氏凤蝶的姐妹物种常常同域分布，并且我们使用最新比较方法得出的推断表明同域物种形成很常见。然而，如果姐妹物种迅速扩散到同域分布（例如由于它们相似的气候生态位），那么我们方法所依据的假设就会被违反。此外，尽管我们发现了一些生态在物种形成中起作用的证据，但生态变化并未显示出同域物种形成预期的与分布范围重叠的关联。我们基于“严格”和“宽松”的生物物种概念（BSC）以及广泛使用的系统发育物种概念（PSC）的“诊断”版本的替代指标，以三种不同方式界定了赫氏凤蝶的物种。我们表明，在赫氏凤蝶中比在鸟类中推断出更多同域物种形成的一个原因可能是两组在物种界定文化上的差异。要确定赫氏凤蝶是否特殊，将需要对更广泛的动物类群进行生物地理比较研究，包括更多的无脊椎动物。
