Paraphyletic species no more - genomic data resolve a Pleistocene radiation and validate morphological species of the Melanoplus scudderi complex (Insecta: Orthoptera)
Paraphyletic species no more - genomic data resolve a Pleistocene radiation and validate morphological species of the Melanoplus scudderi complex (Insecta: Orthoptera)
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DOI：
10.1111/syen.12415
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发表时间：
2020-01-06
影响因子：
4.8
通讯作者：
Knowles, L. Lacey
中科院分区：
文献类型：
--
作者：
Huang, Jen-Pan;Hill, JoVonn G.;Knowles, L. Lacey
快速的物种形成事件，在短时间内产生的类群，是研究最多的生物现象之一。然而，分子系统学往往揭示矛盾的结果相比，最近和快速多样化的情况下物种的形态/表型诊断。在这项研究中，我们使用的分子数据平均超过29 000个基因座每个样本从RADseq重建的多样化历史，并划定物种边界的短翅蝗虫物种复合体（Melanoplus scudderi组），其中更新世的多样化已被假设为产生20多个推定的物种与不同的男性生殖器形状。我们发现，基于最大似然分子系统发育，每个形态的物种确实形成一个单系群，从以前的线粒体DNA序列研究的结果相反。通过测定多样化事件的年代，物种复合体估计在晚更新世期间已经多样化，支持最近的辐射假说。此外，基于聚结的物种划界分析提供了独立的遗传谱系，这对应于形态学定义的物种的定量支持。我们的研究结果还表明，雄性生殖器的形状可能无法预测的物种之间的进化距离，不仅表明这一特征是不稳定的，但也意味着选择可能发挥作用的字符分歧。此外，我们的研究结果表明，在这个不会飞的蝗虫复杂的快速物种形成事件可能主要与他们的草原栖息地在晚更新世的碎片。总的来说，我们的研究强调了整合多个信息来源来描述物种的重要性，特别是对于一个物种复合体，迅速多样化，其分歧可能与生态过程，创造地理隔离（即破碎的栖息地），以及选择作用于字符生殖隔离（即生殖分歧）的直接后果。
Rapid speciation events, with taxa generated over a short time period, are among the most investigated biological phenomena. However, molecular systematics often reveals contradictory results compared with morphological/phenotypical diagnoses of species under scenarios of recent and rapid diversification. In this study, we used molecular data from an average of over 29 000 loci per sample from RADseq to reconstruct the diversification history and delimit the species boundary in a short-winged grasshopper species complex (Melanoplus scudderi group), where Pleistocene diversification has been hypothesized to generate more than 20 putative species with distinct male genitalic shapes. We found that, based on a maximum likelihood molecular phylogeny, each morphological species indeed forms a monophyletic group, contrary to the result from a previous mitochondrial DNA sequence study. By dating the diversification events, the species complex is estimated to have diversified during the Late Pleistocene, supporting the recent radiation hypothesis. Furthermore, coalescent-based species delimitation analyses provide quantitative support for independent genetic lineages, which corresponds to the morphologically defined species. Our results also showed that male genitalic shape may not be predicted by evolutionary distance among species, not only indicating that this trait is labile, but also implying that selection may play a role in character divergence. Additionally, our findings suggest that the rapid speciation events in this flightless grasshopper complex might be primarily associated with the fragmentation of their grassland habitats during the Late Pleistocene. Collectively, our study highlights the importance of integrating multiple sources of information to delineate species, especially for a species complex that diversified rapidly, and whose divergence may be linked to ecological processes that create geographic isolation (i.e. fragmented habitats), as well as selection acting on characters with direct consequences for reproductive isolation (i.e. genitalic divergence).