Doctoral Dissertation Improvement Grant: Primate Interspecific Interactions

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A significant role for hybridization (i.e. interbreeding) between individuals from different biological populations is increasingly being recognized in the evolution of human and non-human primates. However, the full evolutionary impact of hybridization between modern humans and other members of the genus Homo remains unclear and highly debatable. Other questions regarding actual levels of genetic exchange and interbreeding within this genus also remain. Unfortunately, the relative antiquity of such events makes these finer grain, yet important details regarding human evolution more difficult than more recent evolutionary events. Studying genetic aspects of hybridization in extinct, non-human primates provides one way to tackle this challenge because non-human primates serve as important analogs of human evolution. This study proposes to use genetic data from two Neotropical monkeys, common (Callithrix jacchus) and black-tufted marmosets (C. penicillata) as anthropological models of hybridization to address the following question: What is the role of past and present hybridization and genetic exchange in shaping primate population histories? To examine this question, genetic material will be sampled within two marmoset hybrid zones, as well from non-interbreeding populations to make inferences about the evolutionary effects of hybridization on the genomes of the both species. C. jacchus and C. penicillata are small, closely-related Brazilian primates that are an especially informative system for the anthropological study of hybridization because (1) in certain parts of their ranges, they are thought to be interbreeding under population conditions similar to that of early humans; (2) parts of their genomes that are conserved and homologous to certain regions within the human genome can be used to study genomic effects of interbreeding; and (3) they exhibit similar flexibility in mating systems as do humans. Additionally, marmosets are of interest to many researchers because they possess a unique suite of biological and social traits such as twinning, cooperative breeding and social suppression of ovulation in females. Yet, few details about the evolutionary history of marmosets are currently available in the primatological literature. The intellectual merits of this project are threefold: (1) this project will provide a multicontext view of primate hybridization in terms of time and space, (2) the project's results will broaden current knowledge about marmoset evolution, and (3) project findings will allow researchers to formulate and test new hypotheses about hybridization in human and other nonhuman primates. This project has broader impacts on primate conservation, international collaboration,and outreach. The data for this project will assist in decisions about primate populationmanagement and conservation for invasive marmoset species and highly endangered primates. The proposed work creates ample opportunities for the exchange and dissemination of ideas about primate hybridization through international collaboration with several Brazilian primatologists. Outreach efforts of this project are aimed to train both American and Brazilian undergraduate students in molecular biology. Additionally, the results of this project will form the basis of scientific inquiry lessons designed for American K-12 students. Finally, this project is part of dissertation research which will aid in the training of a female doctoral student.