Thore Bergman - US grants

DESCRIPTION (provided by applicant): Our long-term goal is to understand the natural communication of nonhuman primates and the cognitive mechanisms that underlie it. Research is relevant to studies of human health for several reasons. To understand the evolution of language, we must understand how our closest animals relatives, the nonhuman primates, use vocalizations in the social interactions. To understand human brain mechanisms, language, and cognition, we need animal models of similar processes in nonhuman primates. Field research on primates living in their natural habitat constitutes a first step in achieving these goals. Our specific aims are to examine the acoustic properties and social function of vocalizations among free-ranging baboons (Papio cynocephalus ursinus). Research is conducted in the Moremi Game Reserve, Botswana. Subjects include two groups of over 100 individually recognized animals. For most individuals, long-term data on age, matrilineal relatedness and dominance ranks are available. The animals are fully habituated to close-range observation by humans on foot. Field methods include observational sampling of behavior, tape-recording of vocalizations and playback experiments. Laboratory methods include computer-based analysis of the acoustic features of vocalizations, and using software designed for the analysis of human speech.

Humans routinely assess other people by relying on information gained during previous experiences with a particular individual (?individual recognition?). Indeed, individual recognition is the primary means of assessment for most primate species. However, a growing body of evidence indicates that humans also use physical characteristics (?quality signals?) as a way to evaluate others ? particularly in the context of competition and mating. One reason why humans might utilize quality signals is because they live in extremely large social groups where they frequently encounter individuals they do not recognize. However, this hypothesis is difficult to test because quality signals are rare among primates, and little is known about the function and use of signaling in non-human primates. Thus, the main objective of this research is to determine how primates living in large groups ?size up? potential rivals and mates ? a task that involves mapping the boundary of where individual recognition ends and where other short-hand means of assessment begin. The subjects for this research are wild geladas (Theropithecus gelada), a monkey that lives only in the highlands of Ethiopia. Geladas are an ideal species for this research for two reasons. First, while the vast majority of primates live in small groups where individuals recognize every group member, geladas (like humans) live in extremely large groups where individual recognition may not extend beyond a small subgroup. Second, male geladas are unusual among primates in having 2 conspicuous traits that may serve as quality signals, a red patch of skin on the chest and neck, and ritualized display vocalizations. By combining behavioral observations, experimental playbacks, and laboratory analysis of fecal steroid hormones, this research addresses 3 questions: (1) What are the limits of individual recognition in gelada society? (2) For recognized individuals, do they base reproductive decisions on this information? (3) Alternatively (or additionally), do geladas use quality signals, such as chest color or vocal displays, to evaluate potential competitors or mates?

The PI and co-PI of this project are committed to integrating research goals with education and conservation at several levels. First, over the course of this three-year project, a post-doc will receive training in playback experiments and hormone analysis, 4-6 graduate students will gain summer field experience, and 6-8 undergraduates will gain experience analyzing data for senior theses. Second, it is expected that 1-3 Ethiopian graduate students in primate behavior will join the project. Third, an Ethiopian counterpart will be sponsored for graduate training in wildlife management. Finally, this project's research presence in the Simien Mountains National Park (currently on the list of World Heritage Sites in Danger) is assisting conservation efforts. Conservation projects that have been initiated thus far include: a census of geladas living in the area, a survey for tourists on park conservation, and a survey for the local people to gauge the degree of human-wildlife conflict. Both the PI and co-PI will continue to dedicate a fraction of their field time to conservation efforts in the area.

Hybrid zones typically encompass a variety of taxonomically and genetically distinct individuals living under similar ecological and social conditions. Thus, hybrid zones represent unique opportunities to separate intrinsic and extrinsic causes of variation among animals. Furthermore, because a variety of animals are in direct competition, hybrid zones are also ideal locations for studies of competitive ability. This project focuses on two species of howler monkeys, Alouatta palliata and A. pigra, with different vocalizationsthat hybridize in a small region in southern Mexico. The research builds on previous morphological and genetic sampling of the hybrid zone and addresses two main questions: 1) what causes vocal variation among A. palliata, A. pigra, and hybrids? and, 2) how do different vocalizations impact competitive ability in the hybrid zone? To address these questions the project integrates molecular, morphological, behavioral, and acoustic data with playback experiments. Sources of vocal differences will be uncovered by comparing vocalizations among purebred and hybrid males to their genetic background, morphology, location, and social setting. The playback experiments involve both males and females and reveals the types of calls that males find intimidating or females find attractive (or both). The study examines the proximate and ultimate factors shaping primate vocalizations, how sexual selection structures admixture and gene flow, and how differences in vocalizations affect sexual selection.

The project is highly collaborative and will strengthen research ties at many levels; between departments at the University of Michigan, between the University of Michigan and Ohio State University, and internationally between US universities and the Universidad Veracruzana in Mexico. In addition to providing considerable training to Mexican and US students, the project will directly benefit conservation through an educational workshop directed to school-age children within the area of hybridization. Furthermore, the presence of a long-term study in the region and the inclusion of Mexican researchers and students will promote primate studies and conservation in Mexico, a country of high biogeographic importance for primates and other Neotropical taxa.

Group living confers a variety of benefits to individuals within the group, including predator detection, defense and high rates of food acquisition. Animals that form groups with close genetic relatives may also benefit from opportunities to help kin at minimal cost, thus increasing the helper's indirect fitness. Individuals in kin groups also gain direct fitness advantages through decreased within group aggression, lowered risk of infanticide, and coalitionary support. However, much of what we know about the effects of kinship comes from relatively simple, single level social systems. We know very little about how kinship works in complex, multi-level societies like those found in modern humans. Moreover, until recently only long-term studies have had the pedigree data to map maternal relatives. Now, genetic techniques that combine non-invasive sampling with PCR-based genotyping allow researchers to evaluate the interaction between relatedness and social systems in species where relationship data are lacking. This project applies these new genetic techniques and detailed behavioral observation to the unusual, highly complex social system of gelada monkeys (Theropithecus gelada). Geladas live in large, multi-level social systems resembling those of many human hunter-gatherer societies. Gelada social structure appears to be considerably more complex than that of their close phylogenetic relatives, the well-studied baboons. Therefore this research provides important new data on kinship-behavior interactions and the evolution of complex societies in mammals.

This project, in collaboration with the University of Michigan Gelada Research Project (UMGRP), offers both genetic and behavioral information on geladas, which are listed as "rare" by the World Conservation Union. The project employs Ethiopian scientists and rangers, and established both multi-intuitional and interdisciplinary collaborations. The co-PI participates in community outreach lectures to Ethiopian guides, tourists, and local K-12 students, as well as giving presentations to elementary school students in the Northeast U.S.

Very little is known about how complex mammalian societies develop from the interaction of individual social behaviors. In dynamic/fluid social groups, two critically important questions are: what brings smaller core groups together, and the flip side of what splits them apart? The research in this study will study the highly social Old World Monkey geladas (Theropithecus gelada). Geladas are an excellent model system to address this question as they have complex social groups and are easy-to-observe terrestrial animals that live at high densities. This research uses a combination of demographic and behavioral data, social network analyses, and population genetic data to pinpoint the individual gelada behaviors that contribute directly to their social complexity. Additionally, using behavioral, life-history, physiological, and reproductive measures, this research will measure the costs and benefits of different social interactions. The results of this research will establish not just how complex societies emerge from individual behaviors but also why the individuals exhibit those particular behaviors, representing a critical step in understanding how some animals, like humans, moved from simple to complex societies.

The long-term project has and will continue to: (1) strengthen collaborative relationships both within the U.S. and between the U.S. and Africa; (2) provide training to American and Ethiopian undergraduate, masters, and Ph. D. students; (3) assist conservation efforts in Ethiopia through the preservation of national parks, (4) provide outreach both within Ethiopia (offering regular seminars on gelada behavioral ecology to both Ethiopian nationals and international tourists), and within the U.S. (through interactive lectures for K-12 students). Specifically, the members of this project have spear-headed Michigan Primate Outreach, which involves a series of age-appropriate lectures on primates and conservation for students of all ages (see project website for all outreach activities: http://www.umich.edu/~gelada/UMGRP/Home.html).