Combining morphological and genomic evidence to resolve species diversity and study speciation processes of the Pallenopsis patagonica (Pycnogonida) species complex
Combining morphological and genomic evidence to resolve species diversity and study speciation processes of the Pallenopsis patagonica (Pycnogonida) species complex
复制标题
DOI：
10.1186/s12983-019-0316-y
复制
发表时间：
2019-09-06
影响因子：
2.8
通讯作者：
Melzer, Roland R.
中科院分区：
文献类型：
--
作者：
Doemel, Jana S.;Macher, Till-Hendrik;Melzer, Roland R.
巴塔哥尼亚白蜘蛛（Pallenopsis patagonica, Hoek, 1881）是一种形态和遗传变异的海蜘蛛，其分类分类具有挑战性。目前，它被认为是一个物种综合体，包括几个遗传谱系，其中许多还没有被正式描述为物种。这个物种复合体的成员出现在巴塔哥尼亚和南极大陆架以及亚南极岛屿周围。这些栖息地受到历史上大规模冰川的强烈影响，以前的研究表明，在冰川极大期，群落仅限于极少数避难所。因此，这些独立避难所的异域物种形成被认为是导致高纬度南半球海洋底栖动物类群高度生物多样性的共同机制。然而，生态物种形成等其他机制很少被考虑或测试。因此，我们对巴塔哥尼加种复合体进行了形态学和遗传学的综合研究，i)利用目标杂交富集方法解决物种多样性问题，以获得多个基因组标记；ii)发现形态特征并分析形态测量以区分物种；iii)研究导致物种复合体内多个谱系的物种形成过程。结果系统基因组学结果支持了巴塔哥尼亚假单胞菌种复合体中大部分的谱系，形态学数据显示一些谱系是具有诊断特征的不同物种。两个谱系分别为P. aulaeturcarum sp. nov. Domel & Melzer， 2019和P. obstulumsuperavit sp. nov. Domel, 2019。然而，并不是所有的谱系都可以在形态上区分，因此可能代表只能通过遗传工具识别的隐种。此外，135次测量的形态测量数据显示物种内部和物种之间存在很大的变异性，没有明确支持同属系统的适应性分化。结论采用目标杂交富集方法，对巴塔哥尼卡海蜘蛛进行了前所未有的分子数据集，并结合广泛的形态学和形态计量学分析，对该类群的分类、系统发育和生物地理学进行了研究。广泛的数据集使我们能够划定物种边界，在此基础上我们正式描述了两个新物种。没有发现正面选择的一致证据，使异域冰川避难所的物种形成成为最可能的物种形成模式。
Background Pallenopsis patagonica (Hoek, 1881) is a morphologically and genetically variable sea spider species whose taxonomic classification is challenging. Currently, it is considered as a species complex including several genetic lineages, many of which have not been formally described as species. Members of this species complex occur on the Patagonian and Antarctic continental shelves as well as around sub-Antarctic islands. These habitats have been strongly influenced by historical large-scale glaciations and previous studies suggested that communities were limited to very few refugia during glacial maxima. Therefore, allopatric speciation in these independent refugia is regarded as a common mechanism leading to high biodiversity of marine benthic taxa in the high-latitude Southern Hemisphere. However, other mechanisms such as ecological speciation have rarely been considered or tested. Therefore, we conducted an integrative morphological and genetic study on the P. patagonica species complex to i) resolve species diversity using a target hybrid enrichment approach to obtain multiple genomic markers, ii) find morphological characters and analyze morphometric measurements to distinguish species, and iii) investigate the speciation processes that led to multiple lineages within the species complex. Results Phylogenomic results support most of the previously reported lineages within the P. patagonica species complex and morphological data show that several lineages are distinct species with diagnostic characters. Two lineages are proposed as new species, P. aulaeturcarum sp. nov. Domel & Melzer, 2019 and P. obstaculumsuperavit sp. nov. Domel, 2019, respectively. However, not all lineages could be distinguished morphologically and thus likely represent cryptic species that can only be identified with genetic tools. Further, morphometric data of 135 measurements showed a high amount of variability within and between species without clear support of adaptive divergence in sympatry. Conclusions We generated an unprecedented molecular data set for members of the P. patagonica sea spider species complex with a target hybrid enrichment approach, which we combined with extensive morphological and morphometric analyses to investigate the taxonomy, phylogeny and biogeography of this group. The extensive data set enabled us to delineate species boundaries, on the basis of which we formally described two new species. No consistent evidence for positive selection was found, rendering speciation in allopatric glacial refugia as the most likely model of speciation.