Evolution of Bill Size Polymorphism in the African Finch Pyrenestes

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Basic and applied aspects of NSF grant BSR-8817336, entitled "Evolution of Bill Polymorphism in the African Finch Pyrenestes." What produces and maintains variation in natural populations is one of the most fundamental and important questions in biology, of the types of variation found in species perhaps none has generated as much debate as the occurrence of polymorphism. Polymorphism occur when two or more distinct interbreeding forms co-occur within a single population. Despite decades of research there are few instances where the mechanisms producing polymorphism are understood. The African estrildid finch Pyrenestes ostrinus represents one of the few known species where a polymorphism is associated with differential resource use. Building on three years of prior research in the tropical forests of Africa proposed research endeavors to determine the genetic and ecological basis of the polymorphism. In so doing the research should provide an empirical foundation for testing current theoretical models for maintaining polymorphism and greatly improve our understanding of how variation is maintained in animals species. While only seven percent of the world's land surface is covered by tropical forests they contain over half of all known species. Tropical forests play a critical role in regulating the earth's climate, provide important storehouses of genetic material for agriculture, are the source of many important pharmaceuticals and provide valuable renewable economic resources. Despite their importance they are disappearing at an accelerating rate. For conservation efforts to be successful there is a critical need for basic biological information tropical rainforests. As part of the proposed research on Pyrenestes critical information important for rainforest conservation will also be collected.