Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

Adaptive radiation of Lake Tana’s (Ethiopia) Labeobarbus species flock (Pisces, Cyprinidae)

Martin de Graaf A C , Eshete Dejen B , Jan W. M. Osse A and Ferdinand A. Sibbing A D

A Experimental Zoology Group, Department of Animal Sciences, Wageningen University, Marijkeweg 40, 6709 PG Wageningen, The Netherlands.

B Amhara Region Agricultural Research Institute, PO Box 794, Bahar Dar, Ethiopia.

C Present address: Western Australia Marine and Fisheries Research Laboratories, PO Box 20, North Beach, WA 6920, Australia.

D Corresponding author. Email:

Marine and Freshwater Research 59(5) 391-407
Submitted: 29 June 2007  Accepted: 3 March 2008   Published: 6 June 2008


Studying species flocks (e.g. Darwin’s finches, Caribbean anoline lizards, East African cichlid fishes) has proven to be highly successful in understanding the forces driving speciation. The only known, intact species flock of cyprinid fishes, the 15 Labeobarbus species in Lake Tana (Ethiopia), includes eight piscivorous species. Piscivory is a rare specialisation among the highly successful (>2000 species) but mostly benthivorous Cyprinidae. The extent and mechanisms of diversification of this remarkable Labeobarbus species flock, particularly among the unexpected piscivorous species, are still largely unknown. In the present study we demonstrate that all 15 Labeobarbus species are segregated to a great extent along spatial, trophic and/or temporal dimensions. The spatial distribution, diet (prey species but not prey size), time of active feeding and predation techniques differed significantly among the eight piscivores. Lake Tana’s cyprinids displayed their retained potential for ecological diversification and speciation, including the uncommon specialisation of piscivory. The latter is probably a result of the absence of common African specialist piscivores in Lake Tana. We suggest that the evolution of Lake Tana’s Labeobarbus species flock at this stage is predominantly structured by ecological selection models. The labeobarbs most likely underwent sequential stages of radiation and speciation: habitat divergence followed by trophic divergence.

Additional keywords: diagnostic bones prey fish, ecological segregation, phylogenetic constraints, piscivory, sympatric evolution.


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