Liu Shiliang, Wang Shuqiao, Chen Qian, Zhou Chuang, Lin Yucheng
Key Laboratory of Bio-Resourses and Eco-Environment (Ministry of Educaion), College of Life Sciences, Sichuan University, Chengdu 610064, China.
The Sichuan Key Laboratory for Conservation Biology of Endangered Wildlife, Sichuan University, Chengdu 610064, China.
Animals (Basel). 2023 Jan 31;13(3):497. doi: 10.3390/ani13030497.
The mitochondrial genome (mitogenome) is recognized as an effective molecular marker for studying molecular evolution and phylogeny. The family Mysmenidae is a group of widely distributed and covert-living spiders, of which the mitogenomic information is largely unclear. In this study, we obtained the first four complete mitogenomes of mysmenid spiders (one aboveground species: , and three cave-dwelling species: , and ). Comparative analyses revealed that their lengths ranged from 13,771 bp () to 14,223 bp (), containing a standard set of 37 genes and an A + T-rich region with the same gene orientation as other spider species. The mitogenomic size of was more similar to that of mitogenomes than that of , which might indicate the convergent evolution of cave spiders. High variability was detected between the genera and . The A + T content, the amino acid frequency of protein-coding genes (PCGs) and the secondary structures of tRNAs showed large differences. and contained almost identical truncated tRNAs, and their intergenic spacers and overlaps exhibited high uniformity. The two species also possessed a higher similarity of start/stop codons for PCGs than the two species. In selective pressure analysis, compared to , had much higher Ka/Ks values, which implies that selection pressure may be affected by habitat changes. In our study, the phylogenetic analysis based on the combination of 13 PCGs and two rRNAs showed that Mysmenidae is a sister clade to the family Tetragnathidae. Our data and findings will contribute to the better understanding of the origin and evolution of mysmenid spiders.
线粒体基因组（mitogenome）被认为是研究分子进化和系统发育的有效分子标记。膜蛛科是一类广泛分布且生活隐秘的蜘蛛，其线粒体基因组信息在很大程度上尚不清楚。在本研究中，我们获得了膜蛛科蜘蛛的前四个完整线粒体基因组（一个地上物种： ，以及三个穴居物种： 、 和 ）。比较分析表明，它们的长度范围从13,771 bp（ ）到14,223 bp（ ），包含一组标准的37个基因和一个富含A + T的区域，基因方向与其他蜘蛛物种相同。 的线粒体基因组大小与 线粒体基因组的更相似，而与 的不同，这可能表明穴居蜘蛛的趋同进化。在 属和 属之间检测到高变异性。A + T含量、蛋白质编码基因（PCGs）的氨基酸频率和tRNA的二级结构显示出很大差异。 和 包含几乎相同的截短tRNA，它们的基因间隔区和重叠区表现出高度一致性。这两个 物种的PCGs起始/终止密码子的相似性也高于两个 物种。在选择压力分析中，与 相比， 的Ka/Ks值要高得多，这意味着选择压力可能受栖息地变化影响。在我们的研究中，基于13个PCGs和两个rRNAs组合的系统发育分析表明，膜蛛科是园蛛科的姐妹分支。我们的数据和发现将有助于更好地理解膜蛛科蜘蛛的起源和进化。
