Répertoire du personnel

Jos Snoeks

Biologie
Vertébrés

KEAFish

The biodiversity, biogeography and evolutionary history of the northern basins of the Great African Lakes : the enigmatic fish faunas of Lakes Kivu, Edward and Albert revisited.

The area of the northern East African rift-valley lakes, Kivu, Edward and Albert (KEA) is one of the most enigmatic regions in terms of its biogeography. The region is situated at the intersection of three major ichthyo-geographic provinces (Nilo-Sudan, East Coast and Congo) (Snoeks et al., 1997; Decru et al., 2019), features a turbulent tectonic history and likely acted as a species reservoir during recent climatic changes, such as the major drought some 15.000 y BP ago, which resulted in a nearly complete desiccation of Lake Victoria. Recently, we have studied the taxonomy of several cichlid and non-cichlid groups and have produced some checklists for parts of the KEA region and adjacent areas in the Congo basin. It has become clear that there is a need to revise the biogeographical puzzle outlined above. Since a strong taxonomic basis is crucial to make biogeographic inferences, we want to revise some key groups (cichlids and non-cichlids) based on a combined morphological and genetic approach. We will combine classical taxonomy with state-of-the-art genomic methods to provide a comprehensive characterisation of the understudied fish fauna of this region. This work will provide key insights into the region’s bio-geographic history, evaluate its role as a species refuge, and test its previously suggested role as the origin of the about 600 species of the Lake Victoria haplochomine cichlid radiation (Verheyen et al., 2003). Our research hypothesis is that an out-of-Kivu origin for cichlids and non-cichlids and the role of refuges of the KEA lakes shaped to a large extent the ichthyo-diversity of the region. While well-studied in temperate regions, the role of refuges in tropical freshwater fishes remains largely overlooked, which makes this study challenging and innovative. (1) We will perform a region-wide COI-scan of all fish groups of the region, except for the haplochromine cichlids (see below) and complement this with additional nuclear markers when necessary. We will then solve the taxonomic issues revealed, to create the necessary solid base to forward evolutionary and biogeographic scenarios. One genus is already earmarked for morphometric revision: the small cyprinids of the genus Enteromius. (2) Because of the uninformative nature of the results of standard sequencing techniques, such as COI-barcoding, in haplochromines, we will concentrate on full genome sequencing for this group. We will especially concentrate on Lake Albert and riverine habitats, because the Lake Edward fauna is already part of an ongoing FWO-PhD programme (Nathan Vranken). We will add samples to this project to enlarge its scope from Lake Edward to the KEA region. For this, the samples need to be properly identified. Major obstacle here is the lack of knowledge of the Lake Albert haplochromines. Hence, a morphometric revision of this assemblage is included. (3) We will use full genome sequencing for selected non-haplochromines in order to acquire the necessary detail to finetune the evolutionary and ichthyo-geographic scenarios. These include the species-rich cyprinid genus Enteromius, the widespread cichlid, Oreochromis niloticus, and the catfish species Clarias liocephalus and Clarias gariepinus. For the latter, a recent publication suggested the possible role of the Great lakes and particularly Lake Kivu as the centre of diversification from where the species spread over Africa (Van Steenberge et al., 2020). If this would also hold for Oreochromis niloticus, Lake Kivu would be the cradle of two of the most cultured tropical fish species in the world. All analyses can be executed based on material collected during the HIPE-Brain project (ending 03/2021), but one expedition to the Kivu area is planned to complement the samples for genetic studies. If required, DNA will be extracted from preserved collection specimens. As outputs, we envisage a database of genetic barcodes for the fishes of the region, revisions and full genome sequences of key fish groups (Lake Albert haplochromines and non-cichlid groups such as Enteromius and Clarias) using standard morphometric and appropriate genetic techniques, phylogeographics and evolutionary history reconstruction for several important fish groups, and formulation of a scenario for the ichthyo-geography of the KEA region.

Investigateur principal:

  • Jos Snoeks
  • Dates:

    2020 2024

    Collaborateurs:

    Partenaires externes:

    Nathan Vrankan (RMCA & KU Leuven), Maarten Van Steenberge (RBINS), Eva Decru (KU Leuven), Hannes Svardal (U Antwerp), Kisekelwa Tchalondawa (ISP-Bukavu, DRC), William Okello (NaFIRRI, Uganda)