Molluscan and Paleoenvironmental Evolution in Lake Pannon


Lake Pannon existed in Hungary and surrounding countries from approximately 12-4 Ma. After its connection with the marine realm was permanently severed at 12 Ma, it hosted a spectacular radiation of molluscs. Some groups evolved from surviving marine lineages, while others evolved from freshwater invaders. Our Lake Pannon research group includes Dana Geary, Hungarian colleagues Imre Magyar, Pal Muller, and Sandor Gulyas, Jay Schneider, and Hilary Sanders. Recently completed work includes a major biostratigraphic revision (Magyar et al. 1999b) and a detailed paleogeographic study of Lake Pannon (Magyar et al. 1999a). Ongoing work includes taxonomic, morphometric, phylogenetic, and geochemical analyses of cardiid and dreissenid bivalves and melanopsid (and other) gastropods. We are addressing questions about evolutionary tempo and mode (in particular, why does geologically gradual change appear to be relatively common in Lake Pannon), the relationship of environmental change to evolutionary change in the lake, and mechanisms for lacustrine speciation.

Iterative evolution in Lake Pannon melanopsids. In two instances (Pontian, above, and Pannonian, below) a smooth shelled form evolved into a shouldered form. Both cases appear to have involved movement from marginal habitats into the lake proper.


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