Patterns of genetic divergence along a 100 km stretch of the Lower Congo River. Collection sites and major features are shown on the map (A). Assignment test results and mtDNA haplotype networks are shown for T. depressum (B), and for L. tigripictilis (C) populations. Circle size and numbers in center of haplotype networks represent the number of identical haplotypes. Number of substitutions between haplotypes represented by black dots when greater than one, and by a broken line with a number for the longest branches. Collection sites in haplotype networks represented by: yellow = Site A, blue = Site B, purple = Site C, grey = Site D, and tan = Site E.