Comparison Of Morphological And Genetic Differences Between Three Different Rapana Venosa Shell Color Group

Rapana venosa is an important economic shellfish in China,mainly in the Yellow Sea,Bohai and the East China Sea,which has high reproduction rate,fast growth and high nutritional value.With the growing demand of Rapana venosa,Rapana venosa has become an important fishery species.Different populations of Rapana venosa have different phenotypes,e.g.the polymorphic shell colors.Genetic and epigenetic diversity can both result in phenotypic diversity.Revealing the Genetic and epigenetic diversity of Rapana venosa will be significant to understand the formation of polymorphic shell colors and artificial breeding.In this thesis,three different shell color populations of Rapana venosa(intermediate color,orange,thread color)was studied.Firstly,the physiological indicators were measured.Their molecular identification was based on COI gene.Microsatellite technology(SSR)was used to analyze genetic diversity.Methylation sensitive amplification polymorphism(MSAP)was also studies to analyze the epigenetic diversity of the different shell color groups of Rapana venosa.The main research is divided into the following three parts:1)The living habits of Rapana venosa,and its analyzed the physiological indexes were observed.Also the development process,reproduction process,and artificial breeding were understood.The intermediate color、orange color and thread color of different groups of Rapana venosa were collected from Qingdao,、Yantai、Dalian and Lianyungang in September 2016 to May 2017.The samples were preserved and extracted by DNA,then morphological measurements were carried out,and morphological differences among different populations were analyzed.The results showed that there were no obvious differences in the ecological habits of the three shells,and the morphological indexes were not significant.2)The genotype sequences of the COI loci of the three populations were determined.The sequences of two Red screw were downloaded from GenBank as the outgroup.The results were analyzed by Bayesian and NJ.The relationship between molecular identification and phylogenetic development was analyzed.The results showed that there were no significant COI sequence differencein among the three populations.A total of 9 microsatellite markers loci were analyzed by screening and optimization of primers,choosing proper primers,PCR amplification,and electrophoresis.High polymorphism was found in three groups.The number of alleles was between 2-19.The expected heterozygosity ranged between 0.5062～0.9418.It was indicated that the genetic differentiation among the three populations was not obvi.orange group diversity is the most abundant.3)The methylation level of three kinds of shell color populations was analyzed by methylation amplified polymorphism(MSAP).The results showed that the methylation level of the three groups reached a high level.The methylation rate of orange population reached 68.36%,the demitint group reached 61.32%,and the thread color group is 64.53%.The methylation level of orange group is the highest.The environmental factors may play important role in formation of shell color polymorphism.