Environmental gradients mediate dispersal evolution during biological invasions

Abstract

Rapid dispersal evolution at the edge of a range expansion can accelerate invasions. However, expanding populations will often encounter environmental gradients that entail a fitness cost of dispersal. We used an eco-evolutionary model to explore how environmental heterogeneity influences adaptation and dispersal evolution during range expansion and, in turn, modulates the speed and predictability of invasion. Environmental gradients opposed the evolution of increased dispersal during invasion, even leading to the evolution of reduced dispersal along steep gradients. Counterintuitively, reduced dispersal allowed for faster expansion by minimizing maladaptation. While evolution across homogenous landscapes caused invasions to be highly unpredictable, even shallow environmental gradients greatly increased invasion predictability. We illustrate our models potential application to prediction and management of invasions by parameterizing it with data from a recent invertebrate range expansion. Overall, we find that environmental heterogeneity and local adaptation strongly modulate the effect of dispersal evolution on invasion trajectories.