Evolutionary genetics of the catfish Clarias gariepinus (Burchell, 1822) in the Congo basin

Abstract

The Congo Basin features among the oldest, largest and biologically richest on earth after the Amazon and before the Mekong. Sadly enough it is the least known. It offers opportunities to study evolution given its treasure of global biodiversity and high aquaculture potential (large hydrographic network and suitable climate). It is within this framework that phylogeographical research has been initiated to understand the origin of the ichthyological fauna and to identify potential strains for the development of aquaculture. The model chosen is the catfish Clarias gariepinus (Burchell, 1822), a species with great aquaculture potential. This fish lives in the Congo River from source to mouth, as well over a large part of the African continent. The results show the presence of four clades and several groups which represent a large genetic differentiation. Evolution is ancestral in the south and north of the Congo Basin (relict population) and represents a Pleistocene colonisation in the Central Basin. Even in a contemporary context, evolution seems to follow these two models. Two hypotheses have been retained to support the causes for the accumulation of diversity: the hypothesis of long-distance dispersal in the Central Basin and the refuge hypothesis in the peripheral zones of the Central Basin. Moreover, the four major clades have been identified to match with four major ichthyological provinces of Africa: Nilo-Sudan, Zambezi, East Coast and Congo. This confirms an ancient connection between the various basins. Hence, the evolution of C. gariepinus in the Congo basin corresponds with that of the fishes and mammals with a high dispersal capacity, which is found in several African basins. Ideally the evolution of the endemic fauna of the Congo basin should be studied in order to compare it with the higher mentioned high dispersal group. It would facilitate our understanding of the evolution of the fish fauna of this large African basin for sustainable management.

Date of Award	22 Dec 2010
Original language	English
Awarding Institution	University of Namur
Supervisor	Jean-Claude MICHA (Supervisor), Filip VOLCKAERT (Co-Supervisor), Maarten LARMUSEAU (Jury), Akirni Faustin KHANG'MATE (Co-Supervisor), Patrick Kestemont (President) & Karine Van Doninck (Jury)