PLATE-TECTONIC REGULATION OF BIODIVERSITY AND CONTINENTAL ENDEMISM

Cycles of supercontinental assembly and disassembly may exert a first-order control on patterns of global biodiversity (Valentine and Moores 1970). Periods of fragmentation could cultivate biodiversity by increasing continental isolation and fostering the formation of distinct marine provinces. Here, we investigate the relationship between skeletonized marine biotas and plate geography from both a global and regional perspective. In the global view, time-series of taxonomic richness from the Paleobiology Database (paleobiodb.org) are compared to a new quantitative index of plate fragmentation and aggregation derived from the GPlates (gplates.org) rotation model. In the regional view, the Laurentian plate is treated as a fixed reference point and its changing relationship to the rest of the globe in terms of richness, endemism, and proximity to other plates is analyzed through time. There is an association between the proportion of endemic taxa present on Laurentia and its distance to other plates, supporting the view that provinciality is partially governed by tectonics. Despite this, the effect sizes of quantitative relationships between biodiversity and continental dispersion are generally small, whether viewed regionally or globally. This finding suggests that although plate dynamics do influence the formation of marine provinces, the geographic distribution of continental blocks, alone, plays a relatively minor role in regulating biodiversity patterns.