I am currently collaborating with Drs. Anthony Di Fiore (University of Texas at Austin) and Eduardo Fernandez-Duque (Yale University) in a comparative study of titi (Plecturocebus discolor) and saki monkeys (Pithecia aequatorialis) at the Tiputini Biodiversity Station, adjacent to Yasuní National Park, Ecuador, to investigate the evolution and nature of social and genetic monogamy. Based on 12 years of systematic observations, we examine demographic characteristics and life history traits of both species, as well as rates of extrapair paternity and the associated population genetic structure in these two closely related primate species. Additionally, we are also investigating their home range use, ranging behavior, and site fidelity to asses their potential of territoriality for both Pithecids.