DISENTANGLING THE DETERMINANTS OF EXTINCTION RISK: INVESTIGATING THE ROLE OF PALEOGEOGRAPHY IN SHAPING PHANEROZOIC EXTINCTION PATTERNS (Invited Presentation)

Determining species vulnerability to extinction is key to understanding macroevolutionary patterns and predicting future biodiversity loss. Extinction over geological timescales results from the interplay of organismal traits, population-level attributes, and extrinsic factors like climate change. However, a relatively under-investigated question is how vulnerability to climate change is influenced by paleogeographic boundary conditions. For marine taxa inhabiting continental shelf environments, their ability to track preferred isotherms may depend partly on continuous dispersal corridors. We hypothesize that taxa on east-west coastlines, isolated islands, and epicontinental seaways are more susceptible to rapid climate changes than those on continuous north-south coastlines.

We tested this hypothesis using the Paleobiology Database. We used five different paleo-plate reconstruction models to map coastlines over the past 540 million years and developed a spatial pathfinding algorithm to determine the distance required for taxa to move 5, 10, and 15 degrees latitude.

Our analysis confirm that paleogeography has a significant influence on extinction risk. Selectivity for the distance to track metric is notably higher during mass extinction events. This contrasts with the selective signal exhibited by other extinction risk predictors, which are typically dampened during mass extinctions.

We tested the importance of paleogeography relative to known predictors of extinction risk, including geographic range, body size, thermal tolerance, and the temperature change for each taxon using an exhaustive model selection procedure. We found that paleogeography is included in the best-supported model based on AIC, and therefore may play a significant role in mediating taxon survival over the Phanerozoic.

Our findings suggest that taxa in geographically-restrictive environments, such as islands, basins, or east-west oriented coastlines are particularly vulnerable to extinction during episodes of rapid climate change. These results highlight the importance of considering paleogeographic context in understanding historical extinction dynamics and forecasting future extinction risk.