Despite a wealth of laboratory data collected on one species of marmosets, the taxonomy of this groups remains highly controversial. Current opinion varies widely on the species diversity within this genus, Callithrix, with between three and fifteen species being recognized by different scientists, and there are many uncertainties about phylogenetic relationships. The major goal of this project is the preparation of a comparable molecular genetic phylogeny of Callithrix, based on DNA sequence variation at both mitochondrial and nuclear loci, using hair samples obtained non-invasively. This phylogeny should resolve many issues in Callithrix systematics, including evolutionary relationships, status of possible hybrids, and the delineation of species and subspecies. Finally, information relevant to broader evolutionary issues will be obtained, including the tempo of evolutionary differentiation in different environments (Atlantic forest vs. Amazonia), and a potential example of orthogenesis, the theory of metachromism.
