Molecular Phylogenetic Of Perinereis And Genetic Diversity Analysis Of Perinereis Aibuhitensis

The genus Perinereis Kinberg,1865, a member of Polychaeta, Nereididae,Nereidinae, included many important economic species, such as P. nuntia, P.aibuhitensis and P. cultrifera. These species, growing fast, were widely distributedalong the coast of China and economically important as bait and medicinal materials.The shape and the distribution of the paragnaths in the maxillary ring and oral ringwere used to describe nereidids. However, the identification of nereidids was oftendifficult since the morphylogical plasticity and the specimens needed specialprocessing to make its pharyngeal eversion.In the present study, phylogenetic analysis of Perinereis was conducted usingmitochondrial and nuclear DNA sequence data to clarify the current taxonomicclassification, and to assess phylogenetic relationships of this genus as well as andanalyzed the effectiveness of these three genes for species identification. Additionally,we estimated the population genetic diversity and genetic structure of Perinereisaibuhitensis in Northwestern Pacific using mitochondrial DNA sequences.1. The taxonomy and phylogeny of PerinereisA molecular phylogenetic analysis of Perinereis was conducted based onmitochondrial (COI and16S rDNA) and nuclear (18S rDNA) DNA sequence data inmultiple perspective. The present study produced a well-resolved phylogeny thatstrongly supported the monophyly of Perinereis. P.wilsoni and P. mictodonta have aclosest relationship and the clade formed by these two species was placed as a sistertaxon to the clade formed by P. nuntia, and the clade formed by these three speciesclustered with P.aibuhitensis. P.cultrifera was the earliest diverging taxon with Perinereis. The phylogenetic tree of COI and16S rDNA could distinguish all speciesstudied, which can be used DNA barcode for species identification. However, severaldifferent species share the same haplotype based on18S rDNA.18S rDNA analysisindicating that18S rDNA can not be used as DNA barcode for species identification.2. Population genetic structure and molecular phylogeography of P. aibuhitensisMolecular phylogeography of P. aibuhitensis in Northwestern Pacific wasanalyzed using mitochondrial COI and Cyt b. A667bp mtDNA COI fragment wasobtained from157individuals. The results showed that the P. aibuhitensis had lowhaplotype diversity and nucleotide diversity compared with the other marineorganisms. No genetically-differentiated geographical clade was observed in NJ tree.The minimum spanning tree showed the frequency distribution of the commonhaplotype in some population was related to the geographic areas (HK, GR WL andJZW). The significant level of genetic structure was detected among7populationswith two exceptions (HK-GR, HY-HD). The demersal habit of adults and limiteddispersal ability of larvas have likely contributed to the genetically heterogeneousamong populations. The mismatch distribution analyses and neutrality tests suggesteda late Pleistocene population expansion for P.aibuhitensis. A334bp mtDNA Cyt bfragment was analysed for155individuals. The results showed that P. aibuhitensis hadlow haplotype diversity and nucleotide diversity. No genetically-differentiatedgeographical clade was observed in NJ tree and minimum spanning tree. Theminimum spanning tree showed that the all halotypes connected on a primaryhalotype, speculated the the existing samples originated from the same ancestor. Thesignificant level of genetic structure was detected among P. aibuhitensis population.The mismatch distribution analyses and neutrality tests suggested a late Pleistocenepopulation expansion for P.aibuhitensis.