Population structuring and historical demography of a common clam worm Perinereris aibuhitensis near the coasts of Shandong Peninsula

To investigate the genetic diversity, population structure and historical demography of Perinereris aibuhitensis, a 684 base pair fragment of the mitochondrial DNA cytochrome oxidase subunit I gene was analyzed in 92 organisms sampled from around the coasts of Shandong Peninsula. The results showed low haplotype diversity and nucleotide diversity in P. aibuhitensis. Topologies of neighbor-joining trees were shallow but the frequencies of common haplotypes indicated recent evolutionary lineages in the associated geographic areas. Significant genetic differentiations were detected among the four sampled populations, reflecting limited gene flow. Neutrality tests and mismatch distributions showed population expansion in P. aibuhitensis, but a recent bottleneck or selection event is indicated for the samples in the Yellow River Estuary and the Jiaozhou Bay.