The role of the Pleistocene mega-lake Palaeo-Makgadikgadi, Kalahari, for the biodiversity and biogeographys of modern non-marine aquatic organism of southern Africa, with special focus on riverine gastropods

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During the last glacial stage a mega-lake possibly existed in the Kalahari basins, southern Africa, which was potentially as large as extant Lake Victoria. The recent genetic investigations of cichlid fish indicate that this Lake Palaeo-Makgadikgadi may play the key role for understanding the modern biodiversity and biogeography of non-marine aquatic organisms of southern Africa. Geomorphological data indicate the former existence of a closed basin lake, therefore questioning the possibility of freshwater conditions and con-sequently the possibility that major radiations of freshwater organisms could take place. The former lake levels, however, have not been correlated with the aid of modern tools and a model describing palaeohydrological conditions does not exist. We chose the approach of reconstructing the palaeolimnology of the late Pleistocene to Holocene lake phases with the aid of fossil gastropods and microfossils such as ostracodes in order to test whether a large freshwater lake actually existed. Integrated research on modern sou-thern African non-marine aquatic gastropod taxa (the fossils of which exist in sediments of Lake Palaeo-Makgadikgadi) which will be studied genetically, will allow testing the results of fish biologists suggesting the palaeolake was a major centre of evolutionary radiations.