Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, China.
Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, China.
Mol Phylogenet Evol. 2018 Sep;126:233-240. doi: 10.1016/j.ympev.2018.04.019. Epub 2018 Apr 22.
The marine mussels (Mytilidae) are distributed in the oceans worldwide and occupy various habitats with diverse life styles. However, their taxonomy and phylogeny remain unclear from genus to family level due to equivocal morphological and anatomical characters among some taxa. In this study, we inferred the deep phylogenetic relationships among 42 mytiloid species, 19 genera, and five subfamilies of the extant marine mussels by using two mitochondrial (COI and 16S rRNA) and three nuclear (18S and 28S rRNA, and histone H3) genes. Phylogeny was reconstructed with a combination of five genes using Bayesian inference and maximum likelihood method, and divergence time was estimated for the major nodes using a relaxed clock model with three fossil calibrations. Phylogenetic trees revealed two major clades (Clades 1 and 2). In Clade 1, the deep-sea mussels (subfamily Bathymodiolinae) were sister to subfamily Modiolinae (represented by Modiolus), and then was clustered with Leiosolenus (subfamily Lithophaginae). Clade 2 comprised Lithophaga (Lithophaginae) and subfamily Mytilinae. Additionally, a Modiolus species and Musculus senhousia (subfamily Crenellinae) were positioned within the subfamily Mytilinae. The phylogenetic results strongly indicated monophyly of Mytilidae and Bathymodiolinae, polyphyly of Modiolinae and Lithophaginae, and paraphyly of Mytilinae. Divergence time estimation showed an ancient and gradual divergence in most mussel groups, whereas the deep-sea mussels originated recently and diverged rapidly during the Paleogene. The present study provides new insight into the evolutionary history of the marine mussels, and supports taxonomic revision for this important bivalve group.
海洋贻贝（贻贝科）分布于全球海洋，占据各种生境，生活方式多样。然而，由于某些分类群之间形态和解剖特征存在模糊性，它们的分类和系统发育仍不清楚。在这项研究中，我们通过使用两种线粒体（COI 和 16S rRNA）和三种核基因（18S 和 28S rRNA 和组蛋白 H3），推断了 42 种贻贝物种、19 属和现存海洋贻贝的 5 个亚科的深系关系。使用贝叶斯推断和最大似然法，结合五个基因重建了系统发育，并用三个化石校准对主要节点进行了松弛时钟模型的分歧时间估计。系统发育树揭示了两个主要分支（分支 1 和 2）。在分支 1 中，深海贻贝（ Bathymodiolinae 亚科）与 Modiolinae 亚科（以 Modiolus 为代表）为姐妹群，然后与 Leiosolenus （ Lithophaginae 亚科）聚类。分支 2 由 Lithophaga （ Lithophaginae ）和 Mytilinae 亚科组成。此外，一种 Modiolus 物种和 Musculus senhousia （ Crenellinae 亚科）位于 Mytilinae 亚科内。系统发育结果强烈表明贻贝科和 Bathymodiolinae 的单系性、 Modiolinae 和 Lithophaginae 的多系性以及 Mytilinae 的并系性。分歧时间估计显示，大多数贻贝群体的分化是古老而渐进的，而深海贻贝则起源于新近，并在古近纪快速分化。本研究为海洋贻贝的进化历史提供了新的见解，并支持了这一重要双壳类群的分类修订。
