This grant permits Dr. Dietz to continue his study of the golden lion marmoset (Leontopithecus rosalia). This marmoset, which is an endangered species, is confined to isolated fragments of forest in a narrow strip along the southeast coast of Brazil. The Poco das Antas Reserve contains a number of these marmoset troops. Dietz and his team will monitor the composition, reproduction and size, quality and overlap of territories for between 20 and 30 groups. Marmosets and tamarins are of particular interest to biologists because they have several distinct kinds of social groupings. Some troops are monogamous; other are centered about a male accompanied by several females; others are organized around a focal female accompanied by several males. Dr. Dietz is examining this variability in order to determine its cause. He will also attempts to determine the relative reproductive fitness for individuals in each type of group. His prediction is that differences in environmental quality lead to different kinds of group composition, and that monogamy is a response to poor resource quality. This research will test that idea. This research is important for two reasons. First, the golden lion marmoset is an endangered species, and efforts are underway to breed them in several zoological parks. The data collected by Dr. Dietz will aid in this goal. Second, different species of primates exhibit different kinds of social organization and the reasons for these differences are not clear. Because these animals have such a wide range of social behavior within a single species, they offer a particularly valuable opportunity to understand this issue.
