Asian clam(Corbicula fluminea)is a commercially important freshwater bivalve in South and East Asia.However,food clam mainly comes from the wild resources,and the natural populations have declined greatly and rapidly due to overfishing and natural habitats degradation.In China,the germplasm resource protection zone of C.fluminea has been set up in Hongze Lake to protect the natural resources.In this paper,genetic structure of four wild C.fluminea populations in Hongze Lake was analysized using ten polymorphic microsatellite DNA loci isolated and characterized by magnetic beads enrichment methods.The results showed that at least four of the loci were observed to have significant heterozygosity deficiency and obvious deviations from Hardy-Weinberg equilibrium(P<0.013)after Bonferroni correction in the four populations.Although values of expected heterozygosity were all above 0.752 and displayed high genetic diversity in the four populations,the level of genetic diversity fluctuated obviously.For example,the genetic diversity of the Jiangba and Linhuai populations was higher than that of the Gaoliangjian and Laozishan populations.The departure from mutation-drift equilibrium with partly heterozygote excesses was detected in all the C.fluminea populations under the IAM models and in Gaoliangjian population under the TPM models using Bottleneck software,which might indicate that the population structure has suffered bottleneck effects in the past,or was about to experience bottleneck effects,as well as the recent population fluctuation.AMOVA analysis across all populations and loci showed that there were the low levels of genetic divergences among the four populations(F_ST=0.017 7<0.05).1.77% of genetic variation was attributed to among populations.It suggested that all C.fluminea populations in Hongze Lake could be protected and managed as a single unit in genetic resource.All the study results would offer theoretical direction for the protection and utilization of the C.fluminea germplasm in Hongze Lake.