Significant population genetic structure of the Cameroonian fresh water snail, Bulinus globosus, (Gastropoda: Planorbidae) revealed by nuclear microsatellite loci analysis

In order to characterize the demographic traits and spatial structure of Cameroonians Bulinus globosus, intermediate host of Schistosoma haematobium, genetic structure of seven different populations, collected from the tropical zone, was studied using six polymorphic microsatellites. Intrapopulation genetic diversity ranged from 0.37 to 0.55. Interpopulation genetic diversity variation clearly illustrated their significant isolation due to distance with gene flow substantially limited to neighbouring populations. The effective population sizes (Ne) were relatively low (from 3.0 to 18.6), which supposes a high rate from which populations would lose their genetic diversity by drift. Analysis of genetic temporal variability indicated fluctuations of allelic frequencies (35 of 42 locus-population combinations, P < 0.05) characteristic of stochastic demography, and this is reinforced by events of bottlenecks detected in all populations. These findings demonstrated that Cameroonian B. globosus were mixed-maters with some populations showing clear preference for outcrossing. These data also suggest that genetic drift and gene flow are the main factors shaping the genetic structure of studied populations.