Molecular phylogeny of four ascidian species inferred from mitochondrial Cytochrome Oxidase subunit I (COI) sequence

Abstract

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.

Keywords:

• Ascidians
• mitochondrial cytochrome oxidase I
• phylogeny
• GNBR

Acknowledgements

The authors wish to thank Dean and Director CAS in Marine Biology and authorities of Annamalai University for providing facilities and Ministry of Environment, Forest and Climate Change, New Delhi, India, for financial support.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

The authors wish to thank Ministry of Environment, Forest and Climate Change, New Delhi, India, for financial support.