Genetic Diversity and Population Structure of the Peanut Worm (Sipunculus nudus) in Southern China as Inferred from Mitochondrial 16S rRNA Sequences

Genetic diversity and population structure of the peanut worm (Sipunculus nudus) were investi- gated by using 536 base-pair fragments of the mitochondrial 16S ribosomal gene. Populations were collected from three locations along the southern coast of China - Beihai, Sanya, and Xiamen. Amplified polymerase chain reaction products were sequenced in both directions and data were analyzed using ClustalX, Arlequin, and MEGA. A total of 69 polymorphic sites and 21 distinct haplotypes were revealed. The mean haplotype and nucleotide diversity of the three pop- ulations were 0.814% and 0.37%, respectively. The Beihai population had the greatest haplo- type and nucleotide diversity, followed by the Xiamen and Sanya populations. Analysis of mole- cular variance (AMOVA) showed significant genetic differentiation among the three populations (Fst = 0.0619, p