The evolution of habitat choice facilitates niche expansion

Matching  habitat choice and local adaptation are two key factors that control  the distribution and diversification of species. We study their joint evolution in a  structured metapopulation model with a continuous distribution of  habitats. Habitat choice follows as the outcome of dispersal with  non-random immigration, a process always acknowledged yet rarely incorporated into theoretical models. For fixed local adaptation,  we find the evolutionarily stable habitat choice as a function linking  the probability of settlement to the local environment. When the local  adaptation trait co-evolves, the metapopulation can become polymorphic. Our main result shows that coexisting strains  with only slightly different local adaptation traits evolve  substantially different habitat choice. In turn, different habitat use  selects for divergent local adaptations. We thus propose that the joint evolution of habitat choice and local adaptation can  facilitate niche expansion via diversification under wide conditions,  also when the local adaptation trait evolving alone would attain an ESS  restricted to a narrower niche.