Schistosomiasis japonica is one of the most serious parasitic diseases in China. Subspecies of the pomatiopsid snail species Oncomelania hupensis transmit the human blood fluke Schistosoma japonicum, the parasite causing the disease. In at least one study involving the subspecies Oncomelania hupensis robertsoni, there was no clear phylogenetic concordance between the mitochondrial and nuclear data, and it was strongly recommended that future studies incorporate more data from nuclear loci in order to better understand phylogeography and host-parasite coevolution (Wilke et al., 2006). In this paper, we explore genetic diversity based AFLP data involving 25 populations throughout mainland China. AFLP is a DNA fingerprinting technique that detects the polymorphism of the whole genome without prior knowledge of the nucleotide sequence, with the high degree of reproducibility and small amount of template DNA needed.
Our AFLP data show that: (1) the genetic diversity within an O. hupensis population increases gradually with snail sample size, and when the sample size is more than 30 individuals, the genetic variation within one O. hupensis population trends to stabilization. (2) There is high intra-population genetic variation on the mainland of China, and these intra-population genetic variations from different areas differ significantly. (3) The considerable genetic differentiation occurs throughout China. (4) The genetic variation among populations of O. h. hupensis is higher than that of O. h. robertsoni. (5) The patterns of genetic differentiation are basically consistent with geographical distribution of snail populations. Our results are similar to the results of allozymes and COI gene sequences, excluding a snail population from Guangxi Province (Gx-1), indicating that there are three distinct subspecies in mainland China, namely O. h. hupensis, O. h. robertsoni, and O. h. tangi. However, our results do not support that the snail population from Guangxi Province belongs to O. h. hupensis.