Experimental evidence for the biological species status in Lake Tana's Labeobarbus flock (Cyprinidae)

Lake Tana (Ethiopia) harbours the only known remaining intact species flock of large (max. 100 cm standard length, SL) cyprinid fishes (15 Labeobarbus spp.). In 'common garden' experiments progeny of the riverine spawning benthivorous L. tsanensis, and of the piscivorous L. truttiformis and L. megastoma was raised under similar environmental conditions to test if interspecific morphological differentiation would occur. Interspecific morphological differences and divergence were clearly observed early in ontogeny (<= 40 mm SL). This study is the first to demonstrate direct proof for the genetic basis of morphological differentiation among these labeobarbs, providing further support that Lake Tana's labeobarb species are true biological species. (C) Koninklijke Brill NV, Leiden, 2010.