9805948 Bowen The amount and pattern of differentiation among populations can result from many factors. A particularly important issue in the study of population structure in birds is the ways in which social systems and fine-scale demography affect population subdivision. Mexican Jays are an excellent subject for the study of genetic structure because of their unique social behavior and their geographic distribution. Their tendency to breed in or near their natal groups, their long lives, and their sedentary nature suggest that gene flow may be reduced relative to other species. The isolation of populations on sky islands at the northern end of the range could further reduce gene flow among those populations and may have resulted in found effects when they were first isolated. This POWRE research will use microsatellite markers to examine population structure in Mexican Jays. Four hypotheses will be tested: 1) isolated populations of Jays are genetically differentiated from one another; 2) populations of Jays from the core range in central Mexico will have less differentiation and higher levels of gene flow than isolated populations; 3) measures of genetic structure and genetic distance developed for microsatellites will provide useful descriptions of genetic structure; and 4) phylogenetic relationships among populations will be consistent with topologies obtained from allozyme and mitochondrial data.
