Climate change-driven extinction in planktonic foraminifera

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Ongoing declines in biodiversity call for accurate predictions of extinction risk arising from climate change. Long-term studies of evolutionary response to climate change require investigation of the fossil record, but very few fossil records allow us to make highly resolved reconstructions of evolution. The exceptionally well-preserved fossil record of planktonic foraminifera, an abundant and wide-spread group of marine zooplankton, allows for detailed analyses of evolutionary change across diverse environmental settings and climate states. Planktonic foraminifera diversity has decreased steadily over the past 5 million years [1,2]. Over this interval Earth's climate transitioned from a warm distinctly unipolar (Antarctic) glacial climate state to become cold enough to support large ice polar sheets in both hemispheres; initially during ~41 thousand year (kyr)-paced glacial cycles, eventually during the large ~100 kyr-paced Ice Age cycles [3]. It is widely suggested that climate played a role in this decline in diversity, but the causes of individual extinctions remain unknown. This project will study all 46 extinctions of planktonic foraminifera species in the past 5 million years in order to investigate common driving mechanisms and early warning signals. Changes in shell size and shape of extinct-going and surviving species will be compared to local records of environmental change using multivariate statistical techniques [4] to test for threshold response behaviour to climate change-forcing.