Figure 2

COI phylogeny of Oncomelania h. robertsoni. Bayesian phylogenetic tree for Oncomelania h. robertsoni under the relaxed clock model inferred from the mitochondrial COI gene (left). The outgroup taxon, O. minima, was removed a posteriori. The two major phylogroups within O. h. robertsoni are labelled I and II. For specimen codes see Table 3 (ingroup sequences taken from GenBank are indicated by the prefix "GB"). A strict clock Bayesian tree of selected specimens of O. h. robertsoni from the Deyang-Mianyang area is shown on the right. Haplotypes from this area are color-coded according to counties (note that specimen GB-M4, previously studied by Attwood et al. [29], also originates from this area). For reasons of clarity, outgroups were removed posteriori and the overall topologies of the two distinct subclades Ia and Ib are indicated by triangles. The age of the MRCM of the two subclades and the respective 95% confidence interval are illustrated by a black bar. For both trees, all Bayesian posterior probabilities ≥ 0.95 are given next to the nodes.