SYSTEMATIC STATUS OF ONCOMELANIA HUPENSIS (GASTROPODA: POMATIOPSIDAE)THROUGHOUT CHINA
George M. Davis ,Zhang Yi ,Guo Yuanhua ,Christina Spolsky (Academy of Natural Sciencens of Philadelphia ,USA)(Institute of Parasitic Disease,Chinese Academy of Preventive Medicine , Shanghai 200025)
Measures of population divergence for Oncomelania can be derived from shell characters, anatomical characters,or molecular genetics distances. This study explores genetic divergence based on allozyme data involving 14 populations widespread throughout China,are in divergent drainage systems,and have different shell phenotypes. The authors examined 25 loci. Nei's genetic distance ranged from 0. 007 to 0. 453.While there is no correlation of increasing genetic distance with geographic distance,the authors found coherent discernable patterns to the genetic differentiation. Careful examination of these patterns provided evidence for one case of cross-country transport of snails,and for the existence of three exceptional populations that appear to indicate that hybridizations between subspecies may have occurred. Excluding these four populations,patterns of genetic differentiation were in general correlated with geographic distribution and shell sculptural and shape characters. These patterns thus served as the bases for subdivision of O. hupensis into three discrete subspecies :O. h. robertsoni ,O. h. tangi and O. h. hupensis.