HIERARCHICAL CONTROLS ON EXTINCTION SELECTIVITY: TESTING THE EFFECT OF ENVIRONMENTAL AND ECOLOGICAL FACTORS ACROSS THE DIPLOBATHRID CRINOID PHYLOGENY

Identifying predictors of extinction risk is important for better understanding the underlying mechanisms driving differential rates of extinction and variation in taxonomic durations. Increasingly, it is recognized that the effects of interacting factors and phylogenetic autocorrelation should be considered when studying extinction selectivity to account for shared evolutionary history and covariation between traits. Here, controls on genus longevity in the global fossil record of diplobathrid crinoids are quantitatively assessed by analyzing the combined effects of multiple factors, including species richness, environmental distribution, and ecomorphologic characters reflecting feeding ecology and/or niche differentiation. A suite of taxonomic and phylogenetic analytical approaches are employed to (1) assess the effects of multiple, interacting factors, (2) statistically compare and rank the relative contribution of individual factors to temporal duration, and (3) evaluate the relative effects of environmental versus ecological factors on taxonomic longevity. Results indicate that differential survivorship of diplobathrid genera is linked to a complex hierarchy of controlling factors. Of the variables considered, species richness is identified as the primary predictor of diplobathrid genus duration, and environmental preference is the secondary predictor; feeding ecology is not identified as a significant predictor. However, comparison of these results to patterns of extinction and survivorship of other crinoid clades suggests feeding ecology is a significant driver of taxonomic longevity across Class Crinoidea as a whole. These results highlight the utility of tree-based investigations of extinction risk and the importance of testing the effects of multiple, potentially interacting factors at different taxonomic ranks.