In this Research Opportunities for Women/ Research Planning Grant, Dr. Priscilla Tucker, at the University of Michigan, proposes a preliminary evaluation of DNA sequence data from the mammalian Y-chromosome for its use in systematic studies. Y- chromosome genes are of interest because they are inherited only through male lineages and, thus, will provide a useful contrast to mitochondrial genes which are inherited strictly through female lineages. Specifically, Dr. Tucker will use DNA probes for a sequence called pY8/B to survey species in the rodent tribe Peromyscini. The distribution of the pY8/b region will be studied in context of the evolutionary history of the group. The exact nucleotide sequences for the pY8/B sequence will also be determined for several species, and the value of the sequence data for inferring the evolutionary history of the group determined. The research will make an important contribution to understanding the origin of biodiversity in mammalian species.