The late Cenozoic Viviparidae (Mollusca, Gastropoda) of the Albertine Rift Valley (Uganda-Congo)

摘要: During late Cenozoic pre-rift times the viviparid genus Bellamya was probably confined to eastern Africa while in Congo Basin occurred genera Neothauma and Kaya (a new described herein). Pliocene, became extinct a relict Lake Tanganyika. All African rift lakes formed during or after Pliocene were colonised by populations of Bellamya, which evolved into lacustrine endemics. The changes shell morphology such as ornamentation functioning protection against predators, are modest repetitive time space. After initial adaptations stasis followed, there is no indication an arms race between prey predator this genus. In western that prior namely Tanganyika Palaeolake Obweruka, instead coloniser. Initially morphological inertia also both and, first four million years its existence, although from outset lake contained abundant highly specialised molluscivorous fishes. About 4.5 Ma major extinction event Obweruka led extermination 50% molluscan species but none molluscivores. Among viviparids, only one survived, isolated reduced numbers. Immediately crisis conchological quantum change occurred, surviving lineage changing strongly ornamented thalassoid form. dramatic deemed have been due focussed selection predators on small populations. A radiative immediately producing still more forms. Obwerukan Neothauma, comparison repeated patterns evolution can be observed viviparids other lakes, provides example true evolutionary yields evidence how it may occurred. fossil record fresh water molluscs Albertine Basin, thanks duration (ca. 12 years), relatively fine resolution (0.5–1.0 years) sound chronostratigraphic framework, unique resource for understanding tempo mode macroevolution.