Ananthan Gnanakkan, Murugan Rajaram
a Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences , Annamalai University , Cuddalore , Tamil Nadu , India.
Mitochondrial DNA A DNA Mapp Seq Anal. 2018 Jan;29(1):121-125. doi: 10.1080/24701394.2016.1253071. Epub 2016 Dec 27.
Ascidians is a crucial group for the studies of deuterostome evolution and the origin of chordates, yet little molecular work has been done to determine the evolutionary relationships and largely unexplored beyond a few species. The phylogenetic analysis are presented for four different species of solitary ascidians, Ascidia virginea, Ascidiella aspersa, Clavelina oblonga and Aplidium fuscum, obtained from Great Nicobar Biosphere reserve (GNBR). Mitochondrial Cytochrome Oxidase subunit 1(COI) gene was amplified and the genetic diversity at the phylogenic level was measured. Bar-coded sequences were extracted with BLAST format from NCBI and the genetic diversity of the submitted sequences were compared with the related ascidian species. Maximum divergences measured among the four species were as follows: Ascidia virginea (96%), Ascidiella aspersa (96%), Clavelina oblonga (94%) and Aplidium fuscum (97%). This is the first report of molecular phylogeny of ascidians from Great Nicobar Biosphere Reserve, Andaman and Nicobar Islands. From this study, we found some stable clades on the evolutionary relationships among these ascidian species that may prompt a reevaluation of some morphological characters.
海鞘是研究后口动物进化和脊索动物起源的关键类群，但在确定进化关系方面所做的分子研究很少，除了少数物种外，大部分仍未被探索。本文对从大尼科巴生物圈保护区（GNBR）获取的四种不同的独居海鞘物种进行了系统发育分析，它们分别是弗吉尼亚海鞘（Ascidia virginea）、粗糙海鞘（Ascidiella aspersa）、长形住囊虫（Clavelina oblonga）和褐色海鞘（Aplidium fuscum）。扩增了线粒体细胞色素氧化酶亚基1（COI）基因，并测量了系统发育水平上的遗传多样性。从NCBI中以BLAST格式提取条形码序列，并将提交序列的遗传多样性与相关海鞘物种进行比较。这四个物种之间测得的最大差异如下：弗吉尼亚海鞘（96%）、粗糙海鞘（96%）、长形住囊虫（94%）和褐色海鞘（97%）。这是关于安达曼和尼科巴群岛大尼科巴生物圈保护区海鞘分子系统发育的首次报告。通过这项研究，我们在这些海鞘物种的进化关系上发现了一些稳定的分支，这可能促使对一些形态特征进行重新评估。
