Meeting Abstract
Most models for the response of organisms to climate change implicitly assume that populations occur in isolation. However, most local populations are nested within broader metapopulations, united by the immigration and emigration of individuals. If a metapopulation is distributed over a broad geographic region, selection on physiological traits may vary such that gene flow among populations alters extinction probabilities. For example, gene flow from populations that are adapted to cooler climates may reduce the ability of other populations to adapt to a progressively warming environment. Alternatively, local selection may be strong enough to overwhelm gene flow, generating and maintaining phenotypic diversity that may increase a species’ resilience to climate change. Here, we examine the degree to which 7 populations of the lizard Anolis sagrei occurring on different islands in The Bahamas exhibit local thermal adaption in the face of gene flow from geographically disparate populations. Islands varied significantly in their thermal regimes, and despite extremely high gene flow among populations, the thermal optimum for sprint performance was strongly correlated with both the mean and maximum environmental temperature of each island. These data suggest that local selection on thermal physiology has overwhelmed the effects of gene flow from maladapted populations, and that metapopulation structure may increase the resilience of A. sagrei to a rapidly changing climate.
