Testing biogeographic hypotheses in Wallacea using freshwater molluscs

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The biogeography of the oceanic island region called Wallacea between the Asian and Australiancontinental shelves has been controversely discussed for almost 150 years. The geology of the regionis extremely complex and an Australian origin of some parts of the Indonesian island Sulawesi inparticular is generally assumed. Specifically, some taxa of Sulawesi are believed to have arrived oncontinental fragments (terranes) from Australia. This intriguing assumption has never been rigorouslytested, though. Geologists disagree on whether these terranes were submerged during their drift fromAustralia, and from a biological perspective most groups are not suited for respective analyses, as thealternative hypothesis of oceanic or airborne dispersal can often not be rejected. We aim to usemolecular phylogenies of several freshwater gastropod taxa to (i) seek the first conclusive evidence foran Australian origin of groups with a notoriously poor dispersal potential on Sulawesi and (ii) to apply amolecular clock approach in order to correlate the arrival of these gastropods on the island with theage of the candidate terranes, and thus identify the most likely terrane. The outcome of this project isexpected to provide a general contribution to the highly complex biogeography of the region and mayalso yield interdisciplinary insights for geologists by indicating the probabality of a subaerial drift ofcertain terranes.