Research On Genetic Diversity Of Thais Luteostoma And Thais Clavigera

Thais luteostoma and Thais clavigera are muricida purpura, with higher economic andnutritional value. Both of them are important fishing targets. However, in recent years, theresource is seriously declining.This study is mainly concerned with Thais luteostoma and Thais clavigera, whosegenetic diversities and structures were researched by the gene sequence determinationtechnology of mitochondrion DNA16S rRNA and COI and multivariate analysis ofmorphology. The conclusion can provide scientific basis for marine resourceassessment,protection, proliferation and cultivation in future. The results are as follows:1. By the multivariate morphological method,115samples of4Thais luteostomapopulations collected from Zhoushan(ZS),Nanji(NJ),Fuzhou(FZ) and Zhuhai(ZH) littoralzones of China. Using Cluster, Principal component, Discriminant and Coefficient ofvariation to test10of the external morphological characteristics. The results of Clusterand Principal component showed that the morphological differences between zhuhai andFuzhou,Nanji and Zhoushan groups were relatively small, while the differences betweenZhuhai and Nanji groups were the biggest. The results of Coefficient of variation showedthat morphological differences between groups have not yet reached the level of subspecies.2. By the multivariate morphological method,132samples of5Thais clavigerapopulations collected from Zhoushan(ZS),Nanji(NJ),Fuzhou(FZ), Zhuhai(ZH) andHaikou(HK) littoral zones of China. Using Cluster, Principal component, Discriminantand Coefficient of variation to test10of the external morphological characteristics. Theresults of Cluster and Principal component showed that the morphological differencesamong Nanji, Fuzhou and Zhoushan groups were relatively small, while the differenceswere relatively big between groups from Haikou and the other four groups. The results ofCoefficient of variation showed that morphological differences between groups have notyet reached the level of subspecies.3. Genetic diversity and structure of Thais luteostoma1) The mitochondrial DNA16S rRNA gene fragment was amplified by PCR toanalyze the414bp base sequence.8mutations and1parsimony informative sites detected in the16S gene fragments.FSTamong populations varied from-0.0789to0.0048，but notsignificant（P＞0.05）．Genetic distance among populations is0.001, genetic distance inpopulation is0.001.AMOVA showed molecular differences within groups was99.12%.genealogical trees are constructed based on NJ and UPGMA.The result showed that thesamples from different groups scattered,no obvious cluster. Tajima’s D was-2.10023（P＜0.05），Fu’s Fs was-7.99651（P=0.000）, Unimodal appeared in the mismatch distribution.2）The mtDNA COI gene fragment was amplified by PCR to analyze the658bp basesequence.36mutations and7parsimony informative sites detected in the16S genefragments.The difference between Zhuhai group and Nanji goup,Fuzhou group wassignificant(0.01＜P＜0.05),but there was gene flow among groups(Nm＞1).The differenceamong other groups was not significant. Genetic distance among populations was0.004~0.006, genetic distance within population was0.002~0.006.AMOVA showedmolecular differences within groups was98.06%. genealogical trees are constructed basedon NJ and UPGMA.The result showed that the samples from different groups scattered,noobvious cluster. Tajima’s D was-2.33271（P=0.000），Fu’s Fs was-25.35681（P=0.000）,Unimodal appeared in the mismatch distribution.The genetic diversity based on16S rRNA and COI shows that Thais luteostoma don’thave significant genetic structure,and have a historical population expansion.4.Genetic diversity and structure of Thais clavigera1）The mitochondrial DNA16S rRNA gene fragment was amplified by PCR to analyzethe414bp base sequence.14mutations and6parsimony informative sites detected in the16S gene fragments.FSTamong populations varied from-0.074to0.075，but not significant（P＞0.05）．Genetic distance among populations is0.002~0.003, genetic distance inpopulation is0002~0.004.AMOVA showed molecular differences within groups was100.51%. genealogical trees are constructed based on NJ and UPGMA.The result showedthat the samples from different groups scattered,no obvious cluster. Tajima’s D was-1.78943（P＜0.05），Fu’s Fs was-10.11827（P=0.000）, Unimodal appeared in the mismatchdistribution.2）The mtDNA COI gene fragment was amplified by PCR to analyze the6584bp basesequence.62mutations and31parsimony informative sites detected in the16S gene fragments.FSTamong populations varied from0.045to0.0955，but not significant（P＞0.05）．Genetic distance among populations is-0.022~0.010, genetic distance in populationis0.0062~0.012.AMOVA showed molecular differences within groups was100.51%.genealogical trees are constructed based on NJ and UPGMA.The result showed that thesamples from different groups scattered,no obvious cluster. Tajima’s D was-1.96586（P＜0.05），Fu’s Fs was-25.22775（P=0.000）, Unimodal appeared in the mismatch distribution.The genetic diversity based on16S rRNA and COI showes that Thais clavigera don’thave significant genetic structure,and have a historical population expansion.