Molecular evidence that the Channel Islands populations of the orange-crowned warbler ( Oreothlypis celata ; Aves: Passeriformes: Parulidae) represent a distinct evolutionary lineage

We used molecular data to assess the degree of genetic divergence across the breeding range of the orange-crowned warbler ( Oreothlypis celata ) in western North America with particular focus on characterizing the divergence between O. celata populations on the mainland of southern California and on the Channel Islands. We obtained sequences of the mitochondrial gene ND2 and genotypes at ten microsatellite data for 192 O. celata from populations spanning all four recognized subspecies. We recovered low levels of divergence between O. celata populations and genetic patterns were consistent with isolation by distance. However, populations on the Channel Islands were genetically divergent from those on the mainland. We found evidence for greater gene flow from the Channel Islands population to mainland southern California than from the mainland to the islands. We discuss these data in the context of differentiation in phenotypic and ecological characters.