Objective: To identify the genetic structure of Oncomelania hupensis in the middle and lower reaches of Yangtze River by using microsatellite DNA molecular markers.
Methods: O. hupensis snails were collected from the provinces of Anhui, Hunan, Hubei, Jiangxi, and Jiangsu, of which 6 polymorphic microsatellite DNA loci (P84, T5-13, T5-11, T4-22, T6-27 and P82) were amplified with fluorescence labeled universal primer. 20-50 snail samples were collected at each spot, adding up to 165 samples. The number of alleles (N(alpha)), inbreeding coefficient (F(IS)), heterozygosity (H), fixation index (F(ST)) of each group snails, genetic distance between/groups, and the polymorphic information content (PIC) were calculated. Cluster analysis was then carried out based on genetic distance, and hierarchical AMOVA calculation was done.
Results: The number of alleles in each population ranged from 3 to 33, and the inbreeding coefficient ranged from 0.143 to 0.539. The average expected heterozygosity and observed heterozygosity ranged from 0.600 to 0.883 and 0.308 to 0.759, respectively, being the highest in Hubei population and the lowest in Jiangsu population. The range of F(ST) value between paired populations was from 0.0006 to 0.0531. The small F(ST) value suggested that genetic differentiation did not occur among the populations. The average polymorphic information content in the populations ranged from 0.511 to 0.850, showing a high polymorphism except the Jiangsu population. Hierarchical AMOVA calculations showed that inter-individual variation of the snails occupied 95.2% of the total variations. Cluster analysis revealed that Anhui group clustered first to Jiangsu, followed with Hunan, Jiangxi and Hubei.
Conclusion: There is a rich diversity in O. hupensis. Cluster analysis shows a consistency with the geographical distribution pattern. The genetic differences among the 5 snail populations are trivial with microsatellite DNA variation mostly present in individuals.