Understanding how animal species are related to each other is fundamental to understanding the diversity of the living world, and provides the framework upon which the rest of biology can build knowledge. Today, new genetic technologies involving the acquisition and analysis of DNA sequence data are providing major new insights in this area, allowing us to understand both how diverse organisms are related to each other and how DNA itself changes over time. One group of animals that is poorly understood is the family of New World monkeys. The application of new DNA technologies to elucidating the relationships among the members of this group has the potential to yield significant amounts of information, clarifying our view of this branch of the primate order and contributing to our overall knowledge about the natural world. Nuclear and mitochondrial DNA sequence data will be collected for representatives of fourteen taxa of New World monkeys. The genes to be studied are the nuclear X-encoded glucose-6-phosphate dehydrogenase locus (G6PD) and the mitochondrial cytochrome c oxidase subunit II (COII) locus. These newly-generated 32 kilobases of DNA sequence data will be combined with existing DNA sequence data for the same two loci from other New World monkey taxa to reconstruct phylogenetic trees of the platyrrhines using a variety of tree-building algorithms (maximum parsimony, maximum likelihood, and distance). These new data will be used to measure the extent of genetic variation within seven genera of platyrrhines and to increase the overall robustness of phylogenetic estimation. Molecular evolutionary rates of change will be compared between these mitochondrial coding and nuclear non-coding regions. The mitochondrial COII data will be examined to gain a better understanding of the rate speedup within haplorhines at this locus. Finally, substitution patterns at the functionally characterized mitochondrial locus will be studied for evidence of constraints on nucleotide substitutions.
