Department of Biological Sciences, 132 Long Hall, Clemson University, Clemson, SC 29634, USA.
Simon F. S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China.
Gene. 2021 Jun 20;786:145624. doi: 10.1016/j.gene.2021.145624. Epub 2021 Mar 31.
The genus Synalpheus is a cosmopolitan clade of marine shrimps found in most tropical regions. Species in this genus exhibit a range of social organizations, including pair-forming, communal breeding, and eusociality, the latter only known to have evolved within this genus in the marine realm. This study examines the complete mitochondrial genomes of seven species of Synalpheus and explores differences between eusocial and non-eusocial species considering that eusociality has been shown before to affect the strength of purifying selection in mitochondrial protein coding genes. The AT-rich mitochondrial genomes of Synalpheus range from 15,421 bp to 15,782 bp in length and comprise, invariably, 13 protein-coding genes (PCGs), two ribosomal RNA genes, and 22 transfer RNA genes. A 648 bp to 994 bp long intergenic space is assumed to be the D-loop. Mitochondrial gene synteny is identical among the studied shrimps. No major differences occur between eusocial and non-eusocial species in nucleotide composition and codon usage profiles of PCGs and in the secondary structure of tRNA genes. Maximum likelihood phylogenetic analysis of the complete concatenated PCG complement of 90 species supports the monophyly of the genus Synalpheus and its family Alpheidae. Moreover, the monophyletic status of the caridean families Alvinocaridae, Atyidae, Thoridae, Lysmatidae, Palaemonidae, and Pandalidae within caridean shrimps are fully or highly supported by the analysis. We therefore conclude that mitochondrial genomes contain sufficient phylogenetic information to resolve relationships at high taxonomic levels within the Caridea. Our analysis of mitochondrial genomes in the genus Synalpheus contributes to the understanding of the coevolution between genomic architecture and sociality in caridean shrimps and other marine organisms.
Synalpheus 属是一个分布于全球热带地区的海洋虾类，具有多种社会结构，包括配对形成、群体繁殖和真社会性，后者仅在海洋领域中在该属中进化。本研究检查了七种 Synalpheus 物种的完整线粒体基因组，并探讨了真社会性和非真社会性物种之间的差异，因为之前已经表明真社会性会影响线粒体蛋白编码基因中纯化选择的强度。Synalpheus 的富含 AT 的线粒体基因组长度从 15421bp 到 15782bp 不等，始终包含 13 个蛋白质编码基因（PCGs）、两个核糖体 RNA 基因和 22 个转移 RNA 基因。一个 648bp 到 994bp 长的基因间隔区被假定为 D 环。在所研究的虾类中，线粒体基因的排列顺序是相同的。真社会性和非真社会性物种之间在 PCGs 的核苷酸组成和密码子使用模式以及 tRNA 基因的二级结构方面没有重大差异。对 90 种物种的完整串联 PCG 补体的最大似然系统发育分析支持 Synalpheus 属及其 Alpheidae 科的单系性。此外，Caridea 虾类中 Alvinocaridae、Atyidae、Thoridae、Lysmatidae、Palaemonidae 和 Pandalidae 科的单系性状态也得到了充分或高度支持。因此，我们得出结论，线粒体基因组包含足够的系统发育信息，可以解决 Caridea 内高分类群水平的关系。我们对 Synalpheus 属线粒体基因组的分析有助于理解 Caridea 虾类和其他海洋生物中基因组结构和社会性之间的共同进化。
