Median joining network of mtDNA HVRI sequences. This network is composed of 464 georeferenced chimpanzee samples spanning Cameroon and Nigeria that were reported in previous studies [22, 23, 26–28] and LWC chimpanzee samples (n = 46). Haplotypes were color coded denoting their region of origin. Samples shown in purple were collected in Nigeria and western Cameroon west and north of the Sanaga River. Samples shown in orange were collected in southern Cameroon south of the Sanaga River.