CAREER: The Evolution of Cooperative Breeding, Reproductive Suppression, and All-Male Groups in a Southern African Ground Squirrel

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The evolution of cooperative breeding, reproductive suppression, and all-male groups in a southern African ground squirrel. Jane M. Waterman In highly social species, reproduction is often monopolized by a few individuals, yet species with more breeding individuals offer an alternative approach to understanding the costs and benefits of sociality. Although most cooperative groups are composed of close relatives, examining sociality among unrelated individuals enables other selective advantages for grouping to be evaluated. The Cape ground squirrel (Xerus inauris) lives in the arid regions of southern Africa in clusters of related females and associated bands of apparently unrelated males. Females and their young are considered to be cooperative breeders because of the delayed dispersal and reproductive suppression of young that help care for offspring. Males live independently of females in amicable all-male bands that persist throughout the year, and only interact with females during breeding. Thus, two different social systems (male and female) coexist in this species, resulting in a social organization unlike that described for any other mammal and providing a unique model for testing hypotheses on the costs and benefits of grouping. This project will test critical hypotheses about the evolution of social behavior in Cape ground squirrels using a combination of behavioral, molecular and hormonal techniques. To understand the evolution of cooperative breeding in females, reproduction, survival, and offspring care of breeders and non-breeders will be examined in groups that differ in size and habitat quality. The reproductive suppression of subadult females will be monitored using hormone assays and correlated with number and behavior of breeders. Genetic relationships of males and the paternity of offspring within the band's home range will be correlated with dominance status. Predator mobbing experiments will examine mobbing as a form of helping behavior in females and a form of paternal care in males (related to the number of offspring in the area). Delayed dispersal by young males will be examined to compare the reproductive payoff of this strategy to that of early dispersers. The research and educational objectives of this project will be highly integrated in a collaboration between the University of Central Florida and the University of Pretoria in South Africa. Much of the research will be conducted by graduate students from both schools who will develop thesis projects based on this proposal. A field course on the ecology and behavior of small mammals in South Africa will be developed for senior undergraduates and beginning graduate students from both schools. This course will use web-based distance learning and an intensive field component to expose students to the theory, methods and analytical tools used in mammalogy, behavioral ecology, and research in general. Thus, this project will lay the foundation for a long-term study of African ground squirrels and collaboration with the University of Pretoria in both research and education.