Cm. Davies et al., Host-parasite population genetics: a cross-sectional comparison of Bulinusglobosus and Schistosoma haematobium, PARASITOL, 119, 1999, pp. 295-302
The genetic population structures of the freshwater snail Bulinus globosus
and its trematode parasite Schistosoma haematobium from 8 river sites in th
e Zimbabwean highveld were compared using randomly amplified DNA (RAPD) mar
kers. There was significant variability between snail populations collected
at different sites, but schistosome populations only showed differentiatio
n at a wider geographical scale (between 2 non-connected river systems). Fo
r snails, genetic distance was better correlated with proximity along river
s than absolute geographical separation. In contrast, schistosome genetic d
istance was better correlated with absolute geographical separation than pr
oximity along rivers. These results are consistent with different dispersal
mechanisms for snails and schistosomes and the implications for host-paras
ite coevolution are discussed.