Thermal niches of planktonic foraminifera are static throughout glacial–interglacial climate change

Significance We examined the degree to which temperature tolerances changed on 8,000-y timescales across 700,000 y of glacial–interglacial climate change. We coupled a new fossil occurrence database of planktonic foraminifera, an abundant type of zooplankton, with Atmosphere–Ocean Global Circulation Model reconstructions of past climates. Our suite of analyses demonstrated that foraminiferal species have not shifted their temperature tolerances in response to glacial cycles; species occupied the same temperature conditions regardless of the magnitude of global temperature change. The limited tendency of planktonic foraminifera to change their tolerances suggests that ongoing global change could hasten local or global extinctions of plankton and other widely dispersing marine species.