The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Almost Carioca: hybridization between introduced populations of Callithrix jacchus and C. penicillata in Rio de Janeiro State, Brazil


1School of Human Evolution and Social Change, Arizona State University, 2School of Life Sciences, Arizona State University, 3Centro de Biociência e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro

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The importance of hybridization in primate evolution is being increasingly recognized and in Brazil evidence of ongoing interbreeding among Atlantic Forest Callithrix (marmoset) species keeps mounting. Marmosets possess a unique suite of primate traits including cooperative breeding and female reproductive surpression. Additionally, several Callithrix species are endangered. Yet, the evolutionary consequences of hybridization within Callithrix are little understood. To better comprehend marmoset hybridization, we are examining interbreeding between C. jacchus and C. penicillata. These species are well adapted to the highly fragmented Atlantic Forest and their introduced populations are sympatric with each other and other marmosets. Additionally, reproductive isolation is relatively low within this young genus. These conditions facilitate frequent hybridization in sympatric areas between C. jacchus and C. penicillata themselves and other marmosets.

We captured, photographed, and collected tissue from 50 exotic marmosets within a hybrid zone in Silva Jardim/Rio Bonito municipalities, Rio de Janeiro state, where introduced C. penicillata and C. jacchus were first noticed in the mid-1980s. Most captured individuals exhibit phenotypes of mixed parental species traits in ear tuft shape and color. Because few individuals display pure phenotypes, a hybrid swarm may possibly exist within our sampling area. Preliminary results from mitochondrial DNA and phenotypic analyses support the hypothesis that inbreeding is extensive. Collected tissues are also being used for analysis of microsatellite loci to quantify ancestry and gene flow of captured animals. These data will provide a needed genetic perspective of Callitrhix hybridization for interpretation of hybridization┬┤s role in marmoset evolution.

This research has graciously been funded by a Fulbright Fellowship, National Science Foundation Doctoral Disseration Improvement Grant (#1061508), ASU Sigma-Xi Research Grant, ASU SOLS FIGG, and International Primatological Society Research Grant.

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