The Study Of Genetic Diversity Of Three Molluscs In Intertidal Zone Of Wenzhou Coastal Islands

There are many coastal islands in Wenzhou,and the hydrological environment is complicated.There are abundant species in the intertidal zone.After many investigations,Liolophura japonica,Reishia clavigera,and Cellana toreuma are found in various islands in Wenzhou.They are widely distributed,so their genetic diversity is analyzed to facilitate rational conservation and development.In this study,we used mitochondrial COI gene and 16 S rRNA to analyzed the genetic diversity of the three dominant species.The main research results are as follows:(1)In this study,a 675 bp COI gene sequence and a 517 bp 16 S rRNA gene sequence were obtained from 13 populations of Liolophura japonica.The total number of COI gene polymorphisms was 41,haplotype diversity index and nucleotide polymorphisms were 0.847 and 0.00601,respectively,and the average nucleotide difference was 4.0578.The total number of polymorphic loci of the 16 S rRNA gene was 9.The haplotype diversity and nucleotide polymorphism were 0.665 and 0.00169,the average nucleotide difference was 0.8712.According to the topological development tree,the haplotypes of different geographical groups were scattered and there was no expected geographical clustering phenomenon,indicating that there was a gene exchange phenomenon in the coastal islands of Wenzhou.(2)In this experiment,158 individuals of Reishia clavigera were obtained,and the sequence of COI and 16 S rRNA gene fragments were determined.The 672 bp COI gene sequence and the 519 bp 16 S rRNA gene fragment were obtained.A total of 57 simple information sites and 51 single mutation sites were detected in the COI gene.The nucleotide diversity and haplotype diversity were 0.008 and 0.978,respectively,and the average nucleotide difference was 5.328.The 16 S rRNA gene detected the parsimony and single mutation sites of 13 and 16,respectively,and the haplotypes were diverse.The developmental topology tree based on haplotypes is simplex,and there are gene exchanges in Reishia clavigera.(3)A total of 120 COI gene fragments with a length of 671 bp and 122 16 S rRNA gene sequences of 505 bp in length were obtained in Cellana toreuma.The COI gene fragment detected 10 single mutation sites,and the haplotype diversity and nucleotide diversity were 0.145 and 0.0003,respectively,and 10 haplotypes were found.The 16 S rRNA gene fragment has a base deletion site with a haplotype diversity of 0.096 and a nucleotide diversity of 0.0002.Five mutation sites define six haplotypes,and haplotype 1 is the major one accounted for 95.1% of all individuals.In this study,the COI gene and 16 S rRNA gene,Tajima's D values were all less than 0,and the difference was significant(P < 0.01).This result indicates that Cellana toreuma has experienced an expansion event.Based on the above experimental results,we can find that the common common species in Wenzhou Island generally exhibit high haplotype diversity and low nucleotide diversity,which is consistent with the genetic characteristics of marine organisms.Despite the high genetic diversity of the three species,the pollution and destruction of marine environment has increased this year.The conservation of the genetic diversity of coastal species still deserves our attention.