Population Genetic Variation Analysis Of Scophthalmus Maximus L. Using RAPD And Microsatellite Technique

Two types of nuclear molecular markers: randomly amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) molecular markers were used to detect the genetic diversity and analyze the genetic divergence among three populations of Scophthalmus maximus L. which were imported respectively from England, France and Spanish in June, 2002. The main results were as follows:1. 60 individuals from 3 populations of Scophthalmus maximus L. were investigated using 20 random primers. A totle of 125 reproducible RAPD bands ranging from 200 to 2500 bp were obtained. The mean percentage of polymorphic loci of 3 populations ranged from 12.80%~20.00%, while Nei's gene diversity were between 0.0142 and 0.0352. And the average Shannon's indices of phenotypic of the populations ranged from 0.0423 to 0.0720. All these polymorphic indices revealed the genetic diversity in different populations differed from each other. But the results revealed that the diversity of intrapopulations was low.Shannon indices and Nei's gene diversity were used to examine the relative apportioning of variation among and within populations, Shannon indices suggested the variation that came from inter-populations was 8.76% ,while 91.24% was from intra-populations. Nei's gene diversity revealed the variation that come from intra-populations was 88.10%. Both results were consistent. The hierarchy analysis of the population answered for Shannon indices, that is, 98.95% of the variance was from intra-populations. At the same tune, the results of Analysis of Molecular Variation (AMOVA) revealed that the variance of inter-populations hadn't affected the total variance of Scophthalmus maximus L. significantly. These results revealed the variance of inter-populations was very low.2. 4 SSR primers were used to investigate 60 individuals from 3 populations. Every primer amplified different number of alleles which ranged from 3 to 9. Primer Smax-03, Smax-04, Smax-01 and T/1TC18 amplified respectively 4,2,9,3 alleles. Using TFPGA software to analyze the allele frequency of 4 loci, we found the Smax-04 was polymorphic in Spanish population, while was monomorphic in English and French population. At the same time, the mean expected heterozygosity (He) of 3 populations ranged from 0.2156~0.3107; the PIC was between 0.1458 and 0.2415. The results was consistent with Shannon indices and Nei's gene diversity.The results of Analysis of Molecular Variation (AMOVA) revealed that 98.95% of the variance was from intra-populations. The variance of inter-populations hadn't affected the total variance of Scophthalmus maximus L. significantly. The experimental results of SSR was also proved the genetic diversity of three imported Scophthalmus maximus L. populations was low.3. We compared the result of RAPD and SSR which suggested that SSR was sensitive than RAPD in revealing polymorphism. SSR can reflect higher level of genetic diversity than RAPD. At the aspect of examining genetic similarity and distance, there was difference between the results obtained by two techniques. As a whole, the result of population genetic structure detected by RAPD and SSR was consistent, yet there was a little difference between intra-populations genetic diversity. This was mainly because of the ability of detecting genetic variance of the two techniques. In summary, results of this study revealed that both RAPD and microsatellites could be successfully employed in and give comparable results for the genetic diversity analysis of Scophthalmus maximus L. All the results suggested that the genetic diversity of intra-populations was very low and the genetic divergence of inter-populations was also very low. So the measures must be enacted to avoid the inbreeding depression of Scophthalmus maximus L. in our country.