Map of South Africa showing sampling localities for Caffrogobius caffer. The two major currents, the Benguela and Agulhas currents are shown, as well as the smaller inshore counter-current to the Agulhas. 1 = Wooley's Pool in False Bay; 2 = Rooiels; 3 = Gansbaai; 4 = Cape Agulhas; 5 = Cape Infanta; 6 = Jongensfontein; 7 = Herold's Bay; 8 = Knysna; 9 = Port Alfred; 10 = Haga Haga. The stepping stone model shows the directionality and relative intensity of gene flow between populations using arrows. The three major marine biogeographic regions in southern Africa are also delineated.