Deep-time climate legacies affect origination rates of marine genera

Abstract

Significance The effect of climate change on biodiversity is dependent on previous climatic trends. For example, climate warming is more deleterious when added to a long-term warming trend. We tested how the interaction of short- and long-term climate change affects origination rates through time. Using data from the marine fossil record, we show that origination rates in the last 485 million years tend to increase when climate cooling is superimposed on longer-term cooling trends. These findings might clarify the ongoing debate on the relationship between climate and origination and underline the complexity of evolutionary dynamics and the presence of intricate interactions in Earth’s system. Biodiversity dynamics are shaped by a complex interplay between current conditions and historic legacy. The interaction of short- and long-term climate change may mask the true relationship of evolutionary responses to climate change if not specifically accounted for. These paleoclimate interactions have been demonstrated for extinction risk and biodiversity change, but their importance for origination dynamics remains untested. Here, we show that origination probability in marine fossil genera is strongly affected by paleoclimate interactions. Overall, origination probability increases by 27.8% [95% CI (27.4%, 28.3%)] when a short-term cooling adds to a long-term cooling trend. This large effect is consistent through time and all studied groups. The mechanisms of the detected effect might be manifold but are likely connected to increased allopatric speciation with eustatic sea level drop caused by sustained global cooling. We tested this potential mechanism through which paleoclimate interactions can act on origination rates by additionally examining a proxy for habitat fragmentation. This proxy, continental fragmentation, has a similar effect on origination rates as paleoclimate interactions, supporting the importance of allopatric speciation through habitat fragmentation in the deep-time fossil record. The identified complex nature of paleoclimate interactions might explain contradictory conclusions on the relationship between temperature and origination in the previous literature. Our results highlight the need to account for complex interactions in evolutionary studies both between and among biotic and abiotic factors.