In patch- or habitat-structured populations, different ecological processes lead to polymorphism at different spatial scales. While spatial heterogeneity and divergent selection favors phenotypic variation between patches, local competition and negative frequency-dependent selection promotes variation within patches. These two processes are influenced by gene flow in opposite ways. On one hand, limited dispersal facilitates the emergence of variation between patches but on the other hand hinders variation within patches. Most of theory however has looked at these two effects of dispersal in isolation of one another. Here, we use a combination of mathematical modelling and computer simulations to investigate how resource variation within and between habitats influences the way natural selection shapes phenotypic variation for a consumer trait. We show that when resources vary both within and between patches, the co-occurrence of divergent and frequency-dependent selection can lead to phenotypic polymorphism for many levels of gene flow, thus expanding the range of parameters under which polymorphism emerges.
- Max Schmid, Claus Rueffler, Laurent Lehmann, Charles D L Mullon. Foraging for locally and spatially varying resources: Where exploitation competition, local adaptation and kin selection meet. American Naturalist. 2023.