MtDNA <italic>COⅠ</italic> sequence diversity of <italic>Gerres limbatus</italic> in coastal waters of China

Abstract

In order to contribute information on genetic background of <italic>Gerres limbatus</italic> in coastal waters of China, 652 bp mtDNA <italic>COⅠ</italic> sequences of 140 individuals from 9 geographic populations were analyzed. 14 mutation sites were found and 13 haplotypes were identified, of which 9 were unique haplotypes and 4 were shared haplotypes. The overall haplotype and nucleotide diversity were low ( <italic>H</italic>_d=0.276±0.050, π =0.000 5±0.000 1 ), of which genetic diversity of populations from the east part of the Qiongzhou Strait ( <italic>H</italic>_d = 0.338-0.456, π = 0.000 6-0.001 1 ) was higher than those in the western Beibu Gulf ( <italic>H</italic>_d =0-0.295, π =0-0.000 5 ). Haplotype network diagrams did not show obvious genealogical and geographic structure. Genetic differentiation coefficicent(<italic>F</italic>_st) showed that there was indistinctively low-middle genetic differentiation between Naozhou population and other populations ( <italic>F</italic>_st= 0.0773-0.1696). No obvious differentiation was found among other populations ( <italic>F</italic>_st=-0.041 5-0.061 2). AMOVA analysis also showed that 95% population variation originated from within the group. The negative overall value of the neutrality test (Tajima’s <italic>D</italic>=-2.254 9; Fu’s <italic>F</italic>_s=-16.472 5 ) and a significant single peak in the nucleotide mismatch distribution were consistent with demographic expansion in the past, and deduced expansion time ranged from about 0.130 4 to 0.043 5 million years ago. Since the overall genetic diversity of the population was less than 0.5 and nucleotide diversity was less than 0.005, it was speculated that <italic>Gerres limbatus</italic> population in coastal waters of China had recently encountered a severe bottleneck effect. The nucleotide diversity of the Ningde and Naozhou populations was relatively high and had a conservation priority. As genetic diversity of populations in the Beibu Gulf was extremely low, measures should be taken to avoid further decline in genetic diversity.