Evolution of unconditional dispersal in periodic environments

TL;DR

This paper demonstrates that in environments with spatial and temporal variability, unconditional dispersal strategies are favored, leading to stable populations with at least one sink patch, contrasting previous assumptions about dispersal evolution.

Contribution

It provides a theoretical proof that spatial-temporal heterogeneity can select for unconditional dispersal, expanding understanding of dispersal evolution in variable environments.

Findings

Unconditional dispersal is favored under certain spatial-temporal heterogeneity conditions.

Stable strategies include at least one sink patch and no source patches.

Simulations support the theoretical results, showing different dispersal outcomes based on heterogeneity sources.

Abstract

Organisms modulate their fitness in heterogeneous environments by dispersing. Prior work shows that there is selection against "unconditional" dispersal in spatially heterogeneous environments. "Unconditional" means individuals disperse at a rate independent of their location. We prove that if within-patch fitness varies spatially and between two values temporally, then there is selection for unconditional dispersal: any evolutionarily stable strategy (ESS) or evolutionarily stable coalition (ESC) includes a dispersive phenotype. Moreover, at this ESS or ESC, there is at least one sink patch (i.e. geometric mean of fitness less than one) and no sources patches (i.e. geometric mean of fitness greater than one). These results coupled with simulations suggest that spatial-temporal heterogeneity due to abiotic forcing result in either an ESS with a dispersive phenotype or an ESC with sedentary and dispersive phenotypes. In contrast, spatial-temporal heterogeneity due to biotic interactions can select for higher dispersal rates that ultimately spatially synchronize population dynamics.