The Research Of Genetic Diversity Of Mactramactra

Mactra veneriformis belongs to Mollusca, Lamellibranchia, Evlame vibranchia, Heterodata, Mactride. It is a kind of economic bivalves, which is normally restricted to the areas of the coasts in China. Some reports about the genetic diversity of some kinds of bivalves have been seen in some articles but have none about Mactra mactra. Random amplified polymorphic DNA (RAPD) analysis and Inter-simple sequence repeat (ISSR) were used to estimate genetic diversity and relationship in DNA of Mactramactra which belong to five districts, Dg, Pk, Zh, Yt, Qd. 27 RAPD primers and 16 ISSR primers were used to assess genetic variation and interrelationship among Mactramactra in these five districts. Among 27 RAPD primers, about 448 polymorphic genetic loci in 457 genetic loci were amplified, and among 16 ISSR primers, 234 polymorphic genetic loci in 240 loci were amplified. Some biological analysis softwares such as POPGEN were used to analysize the data. The results indicated that the level of genetic diversity examined by RAPD was higher than that by ISSR. The standard of genetic diversity investigated by these two molecular genetic markers such as Na, Ne, Ht, I were high. What's more, the level of genetic flow was high. The coefficient of gene differentiation GST was lower than 0.5. These results revealed that the genetic diversity of these five populations was high, but mainly presented within populations not among populations. It was gene flow that led to high genetic identity among the five populations. The comparision made within the values revealed that gene flow and genetic identity remarkably related to the distance among these populations. The further the geographic distance between two populations was, the weaker was the gene flow, the higher was the GST, and the lower was the gentic identity. The genetic identity gained by RAPD and ISSR was high (the mix was 0.89), which indicated that these five populations did not differentiate into different populations under different enviroment, did belong to the same geographic strain. The dendrograms based on RAPD and ISSR data were similar but not the same. Although the results by RAPD and ISSR revealed that there was closely relationship among the three districts of Liaoning and also the two districts of Shandong. The result by ISSR showed that in the three districts of Liaoning, Pk was closely related to Zh and should be clustered firstly. On the contrary, RAPD indicated that Dg and Zh should be clustered firstly.ISSR and RAPD both indicated that genetic diversity of Pk in these five populations was highest, Dg's was lowest.