Fig. 1

Sampling localities in Lake Victoria and photographs of cichlid species. a Map of the southern half of Lake Victoria showing the cichlid sampling localities. Numbers indicate collection localities: 1, Offshore Ukara; 2, Offshore Kerebe; 3, Irugwa; 4, Karaju; 5, Usengere; 6, Kweru; 7, Offshore Lyamwenge; 8, Nansio; 9, Offshore Nyakanyasi; 10, Offshore Makobe; 11, Offshore Mabibi Island; 12, Vessi Island; 13, Offshore Magu Bay; 14, Offshore Makobe; 15, Kayenze; 16, Bwiru Point; 17, Bwiru Point-hippo; 18, Offshore Hippo; 19, Kissenda Bay; 20, South Offshore Chankende; 21, Nyegezi Bay; 22, Nyaruwambu; 23, Nyameruguyu (Python); 24, Offshore Marumbi; 25, Mwabulugu; and 26, Gabalema. b Photographs of cichlid species, with abbreviations for species names and the numbers of individuals used in this study for each species. Fish species order is from shallow- (left-top) to deep-water (right-bottom). The maps were drawn by Y. T. based on original source maps: https://www.google.com/maps. Fish photographs were taken by M. I. and S. M