PDF(Pubmed)
Abstract：
Delimiting species across a speciation continuum is a complex task, as the process of species origin is not generally instantaneous. The use of genome-wide data provides unprecedented resolution to address convoluted species delimitation cases, often unraveling cryptic diversity. However, because genome-wide approaches based on the multispecies coalescent model are known to confound population structure with species boundaries, often resulting in taxonomic over-splitting, it has become increasingly evident that species delimitation research must consider multiple lines of evidence. In this study, we used phylogenomic, population genomic, and coalescent-based species delimitation approaches, and examined those in light of morphological and ecological information, to investigate species numbers and boundaries comprising the Chirostoma \"humboltianum group\" (family Atherinidae). The humboltianum group is a taxonomically controversial species complex where previous morphological and mitochondrial studies produced conflicting species delimitation outcomes. We generated ddRADseq data for 77 individuals representing the nine nominal species in the group, spanning their distribution range in the central Mexican plateau.
Our results conflict with the morphospecies and ecological delimitation hypotheses, identifying four independently evolving lineages organized in three geographically cohesive clades: (i) chapalae and sphyraena groups in Lake Chapala, (ii) estor group in Lakes Pátzcuaro and Zirahuén, and (iii) humboltianum sensu stricto group in Lake Zacapu and Lerma river system.
Overall, our study provides an atypical example where genome-wide analyses delineate fewer species than previously recognized on the basis of morphology. It also highlights the influence of the geological history of the Chapala-Lerma hydrological system in driving allopatric speciation in the humboltianum group.
Our results conflict with the morphospecies and ecological delimitation hypotheses, identifying four independently evolving lineages organized in three geographically cohesive clades: (i) chapalae and sphyraena groups in Lake Chapala, (ii) estor group in Lakes Pátzcuaro and Zirahuén, and (iii) humboltianum sensu stricto group in Lake Zacapu and Lerma river system.
Overall, our study provides an atypical example where genome-wide analyses delineate fewer species than previously recognized on the basis of morphology. It also highlights the influence of the geological history of the Chapala-Lerma hydrological system in driving allopatric speciation in the humboltianum group.
摘要：
在物种形成连续体中确定物种是一项复杂的任务，因为物种起源的过程通常不是瞬时的。全基因组数据的使用为解决复杂的物种划界案件提供了前所未有的解决方案，经常解开神秘的多样性。然而,因为已知基于多物种合并模型的全基因组方法会混淆种群结构与物种边界，通常导致分类学上的过度分裂，越来越明显的是，物种划界研究必须考虑多种证据。在这项研究中,我们使用了系统基因组，群体基因组，和基于合并的物种划界方法，并根据形态和生态信息检查了这些信息，调查Chirostoma\“humboltianum组”（Atherinidae家族）的物种数量和边界。humboltianum组是一个在分类学上有争议的物种复合体，先前的形态学和线粒体研究产生了相互矛盾的物种划界结果。我们生成了77个个体的ddRADseq数据，代表该组中的9个名义物种，跨越它们在墨西哥中部高原的分布范围。
我们的结果与形态物种和生态定界假设相冲突，确定在三个地理上有凝聚力的进化枝中组织的四个独立进化的谱系：（i）查帕拉湖中的chapalae和sphyraena组，（ii）帕兹夸罗湖和齐拉胡恩湖的estor小组，和（iii）Zacapu湖和Lerma河系的humboltianumsensustricto组。
总的来说，我们的研究提供了一个非典型的例子,其中全基因组分析描述的物种比以前基于形态学认识的物种少.它还强调了Chapala-Lerma水文系统的地质历史对推动humboltianum组的同种形态形成的影响。
我们的结果与形态物种和生态定界假设相冲突，确定在三个地理上有凝聚力的进化枝中组织的四个独立进化的谱系：（i）查帕拉湖中的chapalae和sphyraena组，（ii）帕兹夸罗湖和齐拉胡恩湖的estor小组，和（iii）Zacapu湖和Lerma河系的humboltianumsensustricto组。
总的来说，我们的研究提供了一个非典型的例子,其中全基因组分析描述的物种比以前基于形态学认识的物种少.它还强调了Chapala-Lerma水文系统的地质历史对推动humboltianum组的同种形态形成的影响。
