Abstract: ISSR-PCR technique was adopted to investigate the genetic variation and genetic structure of six Scylla paramamosain geographic populations (QH, DJ, QZW, LSW, ZZW, and ZK) in the Beibu Gulf of South China. A total of 111 individuals were amplified by 8 ISSR primers, and 66 valid loci were analyzed, of which, 56 loci were polymorphic. The percentage of polymorphic loci (PPL) was 84.85% at species level. The PPL of the six populations ranged from 51.52% to 63.64%, with an average of 57.58%. The genetic diversity of the six populations decreased in the order of QH > DJ >QZW> LSW >ZZW >ZK. The PPL and the Shannon′s information index at species or population level showed that the genetic diversity of S. paramamosain arrived at a higher level within the crustacean, but was still lower than that of the other several marine animals of economic importance. The total coefficient of genetic differentiation (G_ST=0.1841) showed that most of the total genetic variation variance (81.59%) indwelled within populations, suggesting a higher level of genetic differentiation among the populations. However, the coefficient of genetic differentiation (G_ST=0.0689-0.1276) of pairwise populations suggested the mediumdegree genetic differentiation among the populations. The analysis of molecular variance (AMOVA) showed that the genetic variation variance within and among the populations accounted for 87.03% and 12.97%, respectively, suggesting that the genetic differentiation among the populations was at a medium level, but the differentiation was significant (P<0.001). The Mantel test suggested that there was no significant correlation between the genetic distance and geographic distance of the six S. paramamosain populations. Clustering analysis showed that the four populations from Guangxi coastal areas could be clustered into a clade.

Key words: coastal saline soils, hyperspectral parameters, soil moisture content, hyperspectral remote sensing.