Marine invertebrate migrations trace climate change over 450 million years

Aim: Poleward migration is a clear response of marine organisms to current global warming but the generality and geographical uniformity of this response are unclear. Marine fossils are expected to record the range shift responses of taxa and ecosystems to past climate change. However, unequal sampling (natural and human) in time and space biases the fossil record, restricting previous studies of ancient migrations to individual taxa and events. We expect that temporal changes in the latitudinal distribution of surviving taxa will reveal range shifts to trace global climate change. Location: Global. Time period: Post-Cambrian Phanerozoic aeon. Major taxa studied: Well-fossilized marine benthic invertebrates comprising stony corals, bivalves, gastropods, brachiopods, trilobites and calcifying sponges. Methods: We track deviations in the latitudinal distribution of range centres of age boundary crossing taxa from the expected distribution, and compare responses across latitudes. We build deviation time series, spanning hundreds of million years, from fossil occurrences and test correlations with seawater temperature estimates derived from stable oxygen isotopes of fossils. Results: Seawater temperature and latitudinal deviations from sampling are positively correlated over the post-Cambrian Phanerozoic. Simulations suggest that sampling patterns are highly unlikely to drive this putative signal of range shifts. Systematically accounting for known sampling issues strengthens this correlation, so that climate is capable of explaining nearly a third of the variance in ancient latitudinal range shifts. The relationship is stronger in low latitude taxa than higher latitude taxa, and in warm ages than cool ages. Main conclusions: Latitudinal range shifts occurred in concert with climate change throughout the post-Cambrian Phanerozoic. Low latitude taxa show the clearest climate-migration signal through time, corroborating predictions of their shift in a warming future.