Control of Reproduction in Diverse Habitats

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We propose to investigate the environmenmtal control of breeding in populations of "crowned sparrows" of the genus Zonotrichia. We have identified key populations in Artic, mid-latitudes and equatorial regions that express the full spectrum of extreme inflexibility of timing (Artic) to almost complete flexibility and asynchrony (equatorial regions). Intermediate degrees of flexibility are found at mid-latitudes. We also have a large corpus of data from a population of Melospiza melodia in western Washington State that expresses a similar cline of reproductive flexibility showing most plasticity in mild, coastal habitats and least flexibility in high altitude habitats in the Cascade mountains. Field experiments will determine how flexible breeding seasons are within each habitat. Parallel laboratory experiments will explore further how environmental signals such as change in day length, temperature, food and water interact with social cues to regulate neuroendocrine and endocrine secretions that orchestrate reproductive development. The results will have practical application on how vertebrates may respond t global change in the near future.