“SURVIVAL OF THE TOLERANT” – A LOGISTIC REGRESSION ANALYSIS OF ECOLOGICAL TOLERANCE SELECTIVITY THROUGHOUT THE PHANEROZOIC

Environmental tolerance and ecological breadth are important predictors of extinction risk in Modern ecosystems, and generalist taxa have been posited to be resistant to extinction relative to specialists. Differential survivorship of ecologically stenotopic or eurytopic taxa has likely had significant macroevolutionary effects following both background extinction and mass extinction events throughout the Phanerozoic, but quantifying environmental tolerance in the fossil record is not straight-forward. We utilize several environmental proxies to assess the ecological tolerance of marine genera, quantitatively assigning taxa as specialist or generalist taxa using a binomial test to assess whether there was significant environmental affinity compared to the proportion of environments within the Paleobiology Database per timebin. We used logistic regression to quantify the depth, substrate, energy level and latitude selectivity towards generalists vs. specialists for background and mass extinction intervals. We find that depth and substrate eurytopicity were the most important variables in determining survivorship throughout the Phanerozoic. Generalist taxa for depth and substrate selectively survived certain mass extinction intervals, and the selective survival of specialists was more common during background intervals. Overall, selectivity based on environmental tolerance is a significant determinant of extinction risk for many background and extinction intervals throughout the Phanerozoic. The difference in selectivity between mass extinctions and background intervals suggests that different extinction causal mechanisms manifest as different selectivity regimes for mass extinction and background extinction throughout the Phanerozoic.