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Honing Bivalve History
What are the lasting effects of extinction, both persistent background extinctions and major events, on surviving lineages? Roy et al. (p. 733) examined the excellent fossil record of marine bivalves over the past 200 million years, which spans the end-Cretaceous extinction. Background extinctions tended to be higher within certain lineages and depended on the previous history of extinctions within those lineages. Cenozoic taxa are still reflecting the end-Cretaceous event.
Evolutionary histories of species and lineages can influence their vulnerabilities to extinction, but the importance of this effect remains poorly explored for extinctions in the geologic past. When analyzed using a standardized taxonomy within a phylogenetic framework, extinction rates of marine bivalves estimated from the fossil record for the last ~200 million years show conservatism at multiple levels of evolutionary divergence, both within individual families and among related families. The strength of such phylogenetic clustering varies over time and is influenced by earlier extinction history, especially by the demise of volatile taxa in the end-Cretaceous mass extinction. Analyses of the evolutionary roles of ancient extinctions and predictive models of vulnerability of taxa to future natural and anthropogenic stressors should take phylogenetic relationships and extinction history into account.