MOORE, Ignacio T.; BONIER, Frances; WINGFIELD, John C.; University of Washington; same; same: Gene flow between two equatorial populations of rufous-collared sparrows, Zonotrichia capensis, with opposed reproductive patterns

Seasonally breeding birds in northern latitudes are typically photoperiodic and use changes in daylength to time reproduction. The environmental cues used for timing of seasonal reproduction have not been well investigated in tropical birds for which photoperiodic cues are often minimal. We have identified two populations of rufous-collared sparrows, Zonotrichia capensis, in Ecuador that are only 25 km apart, but have diametrically opposed rainfall patterns because they are on opposite slopes of the Andes. Both sites are on the equator and are at high elevation with limited seasonal environmental changes other than rainfall. The two populations appear to breed primarily during their respective dry seasons. Because of these distinct breeding phenologies, we predict that the two populations are genetically isolated. To test this prediction, we are screening 24 individuals (12 male, 12 female) from each population at seven microsatellite loci. If we detect limited gene flow between the two populations, this would suggest a genetic basis for the difference in breeding phenology. In contrast, high levels of gene flow would suggest that timing of reproduction is a plastic trait, adapted to local environmental cues.