Long-Lived Lake Molluscs as Island Faunas: A Bivalve Perspective

Abstract

The evolutionary biology of long-lived lake bivalves, a group that has received comparatively little attention compared to, for example, gastropods and ostracods, is reviewed. Bivalve faunas of different (fossil and extant) long-lived lakes are characterised, and evolutionary aspects, such as the paucity of radiations of common cosmopolitan freshwater groups like sphaeriid and corbiculid clams are addressed. Special attention is given to the corbulid radiations in Miocene Lake Pebas of Western Amazonia. The ability to evolve morphological and ecological characteristics in long-lived lake biota that exceed the range of variation of their relatives in “ordinary” (non-long-lived lake) environments is discussed and termed “supralimital evolution”. Several examples are discussed that show that such evo- lution is facilitated by the availability of empty biotopes after ecological crises in ecosystems at the onset of long-lived lake stages that are stable on ecological time scales. Implications for uniformitarian applications of long-lived lake biota are discussed.