Regions in Serbia and Montenegro with the broader Iron Gate Gorge area (A), Adriatic Sea basin of Montenegro (B) and southwestern Serbia (C), where the populations of brown and tentative Adriatic and Macedonian trout were sampled (1, River Rečka; green quadrate denotes the Bledaria waterfall; 2, River Vratna; 3, River Zamna; 4, River Mrtvica; 5, River Nožica; 6, upper River Zeta; 7, lower River Zeta, red rectangle marks the subterranean drop; 8, River Studenačka; 9, River Vlasina; 10, River Džepska; 11, River Vrla; 12, River Božica). The dashed line denotes the peninsular divide between Adriatic, Black and Aegean Seas.