The legacy of a snail conquest: from pattern to process in a presumably ancient radiation of freshwater gastropods across the South Pacific

• Applicant: Professor Dr. Martin Haase
• Subject Area: Evolution, Anthropology
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 179086697

Across the South Pacific islands, rissooidean freshwater gastropods have a peculiar distribution occurring almost exclusively on archipelagos with parts that are at least 10 Mio years old. This suggests that the entire radiation is among the oldest among animals in the region. Anatomical investigations indicated that these snails from New Zealand, New Caledonia, Vanuatu, Fiji and the Austral Islands form a monophyletic group. The only marine/brackish water relatives occur in New Zealand, where these snails were shown to have colonized freshwater three times independently. Based on these facts and findings, it has been hypothesized that the entire Pacific radiation had its origin in New Zealand from where the snails dispersed to the other archipelagos. In this group of snails, phylogenetic relationships can only be inferred from DNA sequence data. Establishing a robust phylogeny including also (possibly) related species from Australia we will test the outlined hypothesis against alternative scenarios, analyze speciation patterns on three levels (intra-island, within archipelagos, across archipelagos), assess the potential impact of extinction on our conclusions, analyze diversity patterns, and put the resulting big picture into a comparative context of general South Pacific biogeography.

• DFG Programme: Research Grants