Song Dialects as Barriers to Dispersal in White-Crowned Sparrows, Zonotrichia leucophrys nuttalli

Baker, Myron; Mewaldt, L

Many avian species exhibit vocal dialects, but the influence of such song differences on population biology remains largely unknown. Genetic differences between two contiguous dialect populations of white-crowned sparrows (Zonotrichia leucophrys nuttalli) in coastal California were previously documented. To extend this result, the hypothesis that white-crowns assortatively mate with others of their native dialect suggests that where these two dialect populations meet one should see reduced gene exchange. A banding and recapture study produced 371 individuals whose sites of fledging and subsequent breeding were located. These cases of generation to generation dispersal are analyzed with respect to gene flow across the dialect border. The results indicate that dispersal follows a gamma probability distribution. A theoretical distribution, in concert with the distances between birth sites and the dialect transition, was used to establish the expected value of cross-dialect gene flow Our observed number of migrants was five in comparison to an expectation of 26. This suggests that song dialects reduce migration.

Song Dialects as Barriers to Dispersal in White-Crowned Sparrows, Zonotrichia leucophrys nuttalli

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