Population genetic structure and phylogeography of the mud-flat crabs <i>Helice tientsinensis</i> and <i>Helice latimera</i> along the coast of China seas based on mitochondrial DNA

Abstract

Genetic structure and evolutionary demography of the mud-flat crabs (Helice tientsinensis and H. latimera) were investigated using sequence data of mitochondrial cytochrome c oxidase I (COI) gene. Samples of 213 individuals were collected from nine localities over most of the species’ range along the coast of China seas. There were 38 variable sites defining 42 haplotypes. Two distinct lineages were detected, which might be divergent in different marginal seas of the Northwestern Pacific during periods of the low sea level. There was a significant difference in geographical distribution frequency between the two lineages. Analysis of molecular variance (AMOVA) and conventional population statistics (FST) revealed significant genetic structure in the 10 populations of H. tientsinensis and H. latimera. For all populations, the AMOVA showed three different groups in the marginal seas of East Asia. Within-lineage variation was also highly structured in the two lineages. Both mismatch distribution and neutrality tests indicate population expansion in the two lineages. The two co-existing lineages in the East China Sea might be explained by population reestablishment after the last glacial maximum.

Key words: Helice tientsinensis, Helice latimera, mtDNA, cytochrome c oxidase subunit I gene, population genetic structure, population expansion.