Species’ ranges may fragment abruptly even when environments change gradually

What is it about?

The study shows that adaptation to changing environments is subject to a critical limit: even when environmental change is gradual, there is a tipping point beyond which adaptation can suddenly fail. This tipping point arises from the feedback between ecological and evolutionary dynamics. Beyond this tipping point, species’ ranges may shrink or even abruptly fragment into separate subpopulations.

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Photo by Matej Drha on Unsplash

Photo by Matej Drha on Unsplash

Why is it important?

In a time of accelerating climate change, we need a predictive theory of species’ range shifts, adaptation, and resilience of populations. This study identifies that feedback between population dynamics and evolutionary processes can trigger a tipping point in adaptation to changing environments. As environments change through time, the genetic composition of a population becomes less well matched to its surroundings. When populations are maladapted, they decline in size and become more susceptible to genetic drift. Genetic drift is a process of random sampling, which depletes genetic variance – yet this variance is necessary for adaptation. When genetic variance declines, adaptation slows down – and the self-reinforcing downward spiral is complete. Due to this feedback loop, even a gradual change can trigger an abrupt fragmentation of a species' range, or its collapse from the margins. Conversely, improving connectivity between neighbouring populations reduces the strength of genetic drift and thus may keep the populations above this critical threshold, preserving their adaptive potential.