In this dissertation, I explored the mating system, social interactions, dispersal behavior, and genetic structure of a population of rainforest lemurs.
I first studied the factors that determine grouping in sifakas. Propithecus edwardsi live in groups of 2-9 individuals including one breeding male and one to two related breeding females. Using the theories of kin selection, ecological constraints, and reproductive skew, I examined the effects of relatedness, environment, and mate availability on cooperation, group composition, and reproduction. To do this, I used standard field behavior methods, conducting focal follows of a population of Milne-Edwards’ sifakas in the submontane rainforest of Ranomafana National Park (RNP) in southeastern Madagascar. Supplementing this information with data from long-term study of this population, I analyzed affiliative and aggressive interactions and biometric data. I also conducted microsatellite analyses to determine paternity and relatedness between individuals. I found that infants were sired by group males. Moreover, social interactions met the predictions of the theories of kin selection and reciprocal altruism.
Propithecus edwardsi show a remarkable system of unbiased sex dispersal. Since most classic theories predict male-biased dispersal in mammals, I developed the Local Mate Availability Model to predict when dispersal should occur in both sexes. Data from 21 years of study of sifakas were used to test the model. Results showed that one factor predicted the majority of dispersal events in this population: presence of an available unrelated opposite sex adult (a “mate”). Most unpredicted dispersal events were the result of aggressive takeovers by immigrant same-sex adults. These takeovers were usually associated with infanticide; both female and male immigrants killed the infants of the group into which they dispersed. As a result of infanticide by male immigrants, females came into estrus sooner. As a result of infanticide by female immigrants, females dispersed out of the group.
Finally, I used population genetics tools to examine the movement of individuals around RNP, focusing on groups found on either side of natural and man-made barriers that divide the protected area. Sifakas there are genetically diverse and RNP has successfully conserved their habitat. However, gene flow may be disrupted by the barrier in the future, with potential management and conservation implications.
|Advisor:||Wright, Patricia C.|
|School:||State University of New York at Stony Brook|
|School Location:||United States -- New York|
|Source:||DAI-B 71/05, Dissertation Abstracts International|
|Subjects:||Wildlife Conservation, Ecology|
|Keywords:||Endangered species, Kin selection, Madagascar, Propithecus edwardsi|
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