Population Genetic Diversity and Differentiation of Cyclina Sinensis (Mollusca Bivalvia) Based on ITS Sequence Analysis

Abstract

This paper preliminary discusses the genetic diversity and differentiation from 9 populations of wild Cyclina sinensis, which distribute in different regions around maritime coasts of China. The investigation was carried out by sequencing ribosome DNA gene internal transcribed spacer 1 (ITS1) sequences. The ITS1 sequence of C. sinensis obtained in this research ranged from 564 to 595 nucleotides in length respectively. 15 haplotypes were identified from 45 individual in 9 populations, Haplotype (gene) diversity Hd=0.965, Nucleotide diversity Pi=0.0312 and the Theta (per site) Eta=0.0294. The alignment sequence containing 607 sites were constant with 58 sites being polymorphism (excluding sites with gaps / missing data). The pairwise distance matrix for the determination of differentiation was produced following the method of Hasegawa, et al (1985) to evaluate the ratios of transition/transversion in nucleotides. The NJ trees were presented the phylogenetic of populations separated as two basic clades; the basic clade was corresponding to the populations from the China Bohai Sea, the Yellow Sea, and the Dong Sea(northern and middle parts of the Sea of China), the second clade contained the populations from the South China Sea and the Japan Sea, the genetic differentiation between two clades was significant. After using the AMOVA program, the result show that the genetic variation were high from populations and groups, but the most Source of genetic variation were from among groups (different Chinese sea). The reasons for the differentiation of populations for C.sinensis were also discussed in this paper.