Maximum credibility phylogeny of
based on mitochondrial COI and 16S data. Bayesian posterior probabilities are given above the nodes (values <0.50 not indicated). Color coding indicates geographical range, with representation of the maximum likelihood reconstructions of ancestral geographic origin at selected nodes; black codes for terminal taxa indicate an African origin; blue ones originate from other continents. Three-letter morph codes are indicated for Melanoides tuberculata. The scale bar represents substitutions per site according to the applied model of sequence evolution. Clades specifically discussed in the text are labeled at their basal nodes with encircled numbers (which also facilitate comparison to Figure 3). Gradient rectangles indicate the invasions here discussed. *indicates sequences obtained from GenBank. The inset map of tropical Africa indicates that invasions (arrows) occurred in areas with high human population density; Lakes Malawi, Tanganyika and Victoria are labelled. Population data were obtained from NASA’s Socioeconomic Data and Applications Center (http://sedac.ciesin.columbia.edu; copyright ownership by the Center for International Earth Science Information Network [CIESIN]; accessed 28 March 2014).