A study published in Physical Review Letters by researchers at MIT and the University of Leicester has provided evidence that the rate of environmental change relative to species' adaptation rates is a key factor in mass extinction events at a global scale.
The Core Hypothesis
The researchers developed a theoretical model based on the 'rate-mismatch' hypothesis, which posits that extinction occurs when environmental change outpaces a species' ability to adapt. They compared the model with paleontological and geochemical data from 27 episodes of carbon cycle change over the last 450 million years, which reflect global environmental changes. The model successfully predicted the severity (fraction of life that went extinct) for most major mass extinctions.
Key Findings
The study found that the range of adaptation rates across animal groups broadly matches the range of rates at which the environment can change. Mass extinctions occurred when a significant fraction of animals could not adapt quickly enough.
A Warning for the Modern Era
The researchers note that current rates of carbon dioxide increase in the ocean, when rescaled, are similar to rates of carbon-cycle change just below those associated with past major extinctions. This suggests that modern environmental change may be approaching rates where adaptation becomes difficult.