Bayesian clustering analysis (STRUCTURE) of Oncomelania hupensis populations, indicating optimal genetic clusters (K = 2). A: Mean (±SD) natural logarithm of the likelihood of the data [LnP(X | K)] for value of assumed clusters (K). B: Delta K value is plotted against the number of assumed K. C: Genetic structure with K = 2. Each individual is represented by a thin vertical line, which is partitioned into K colored segments that represents the individual’s estimated membership fractions in K clusters. Black lines separate individuals of different populations. The figure shown for a given K is based on the highest probability run at that K. Populations are labelled below the figure.