Habitat selection and nicHe conservatism

Niche conservatism is the phenomenon in which species or other phylogenetic lineages seem to exhibit much the same ecological niche over their geographical ranges or over evolutionary time scales. Previous studies have suggested that optimal habitat selection can constrain niche evolution (and thus may help explain niche conservatism), in effect by preventing populations from experiencing unfavorable sink environments with conditions outside the niche. This paper relaxes a key assumption in prior literature, by allowing habitat selection decisions to be conditional upon an individual’s phenotype. We use individual-based simulations of evolution in source–sink landscapes to examine the consequences of phenotype-matching habitat selection. If each individual obeys a “perfect” habitat selection rule—moving to another habitat only if that movement increases the match between its phenotype and the habitat’s optimum—then habitat selection can speed up the rate of adaptation to sink environments, and thus facilitate niche evolution. We also note that habitat selection can also indirectly influence the pool of variation available for selection, and thereby potentially alter to some degree this conclusion.