Asymmetric patch size distribution leads to disruptive selection on dispersal

Area of Science:

• Evolutionary Ecology
• Landscape Ecology
• Population Genetics

Background:

• Models often predict uniform dispersal rates at evolutionary equilibrium.
• Dispersal rate diversification typically requires environmental fluctuations or perturbations.
• Natural populations exhibit significant variation in dispersal ability, even in stable environments.

Purpose of the Study:

• To investigate the evolutionary drivers of dispersal rate diversification in fragmented landscapes.
• To demonstrate that patch size heterogeneity can induce diversification in dispersal strategies.
• To provide a parsimonious explanation for observed variation in dispersal ability.

Main Methods:

• Utilized a simple island model without temporal environmental variability.
• Simulated scenarios with heterogeneous patch sizes (many small, few large).
• Analyzed the impact of patch size distribution on inclusive fitness variance.

Main Results:

• Disruptive selection on dispersal evolves in heterogeneous patch size environments.
• High variability in the number of related patch mates drives this selection.
• Per capita variance in inclusive fitness is a key mechanism.

Conclusions:

• Patch size asymmetry is a sufficient condition for dispersal trait diversification.
• This mechanism offers a testable explanation for natural dispersal variation.
• Conservation policies should maintain asymmetric and variable patch size distributions.