Comparative Analysis of Genetic Diversity and Population Structure of Sipunculus nudus as Revealed by Mitochondrial COI Sequences

Genetic diversity and population structure of Sipunculus nudus were evaluated using a 652 base pair fragment of the mitochondrial cytochrome oxidase I gene. The populations were collected from Beihai, Sanya, and Xiamen. A total of 71 polymorphic sites defined 16 distinct haplotypes. The mean haplotype diversity and nucleotide diversity of the three populations were 0.9354 ± 0.0168 and 0.0035 ± 0.0018, respectively. Analysis at the intrapopulation level showed that the Beihai population had the greatest haplotype and nucleotide diversity, followed by the Xiamen and Sanya populations. Analysis of molecular variance showed significant genetic differentiation among the three populations (Fst = 0.0796, P < 0.05). The present results revealed that S. nudus populations had a high level of genetic diversity and distinct population structures.