Genetic diversity and population structure of penis fish (Urechis unicinctus) based on mitochondrial and nuclear gene markers

Abstract

Urechis unicinctus is distributed only in Bohai Gulf of China and Korean and Japanese coast. The wild populations of this species have sharply declined in China and Japan. We collected 105 samples from six localities of Bohai Gulf and Korea coast, and investigated genetic diversity and population structure with mitochondrial COI, 16S-rRNA and nuclear 28S-rRNA gene fragments. Genetic diversity of U. unicinctus based on COI sequences was still high (Hd: 0.9595, π: 0.0101), however, 28S-rRNA gene sequences showed low level of genetic diversity (Hd: 0.4084, π: 0.0007). Based on COI sequences, F_ST values between populations ranged from −0.00204 to 0.05210, and 99.12% genetic diversity was contributed by different individuals within population. Both phylogenetic trees and median-joining network did not show clear geographic cluster, haplotypes from different populations were mixed. Our results indicated low level of genetic divergence among different localities of U. unicinctus, and this species should be treated as a whole population among China, Japan and Korea coast during species conservation.

Keywords:

• Urechis unicinctus
• genetic diversity
• population structure
• COI
• 16S-rRNA
• 28S-rRNA

Disclosure statement

The authors declare that they have no conflict of interest. The authors alone are responsible for the content and writing of the article.

Compliance with ethical standards

This article does not contain any studies with human subjects by any of the authors. The animal experiment throughout the study was conducted according to the Chinese Ministry of Science and Technology Guiding Directives for Humane Treatment of Laboratory Animals.

Additional information

Funding

This work was supported by the Natural Scientific Foundation of China (No. 31371252), the open project from the State Key Laboratory of Genetic Resource and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences (GREKF15-04) and Science and Technology Development Plan of Yantai (2015ZH089).