The purpose of this study is to examine several aspects of the evolutionary history of the jays in the genus Aphelocoma. Biochemical comparisons of enzymes (starch-gel electrophoresis) from different populations throughout the species' ranges will be used to generate phylogenetic (genealogic) hypotheses for the populations under study. Then, using those phylogenetic hypotheses, three other aspects of the evolutionary history of the genus will be investigated. First, the historical geography of the genus will be evaluated through an analysis of the relationship between phylogenetic relationship and geographic proximity. Second, the processes leading to the formation of new species in the genus will be studied by determining the amount of genetic differentiation associated with different types of barriers to dispersal. Finally, historical morphological characteristics will be estimated through procedures designed to approximate the most likely sequence of evolutionary changes in the morphology of the species. Thus, this study will produce important information on the details of the evolutionary history of the Aphelocoma jays, information which is available for few avain species.
