Craig Packer - US grants

Different primate species are characterized by differing patterns of dispersal. It is generally felt that the dispersal pattern is an adaptation which may increase the selective fitness of individuals by increasingly their likelihood of mating and hence passing their genes on to subsequent generations. Both chimpanzees and baboons are present in the Gombe Forest of Tanzania and each demonstrates a different dispersal pattern. Among chimpanzees, about half of the females leave their natal group permanently and half leave temporarily. Among the baboons, it is the males who emigrate but the age of first dispersal varies from 3 to 9 years. Additionally, some female baboons leave their natal range at the time when groups divide. In order to attempt to understand the costs and benefits of the different patterns, the PIs will cooperate with Jane Goodall in the use of her detailed field notes; notes which extend back for as much as 20 years. In addition, they will extend the studies of both species at Gombe for the next three years by direct observation. In cooperation with Tanzanian scientists, they will also test the relationship of the richness of the habitat to the dispersal patterns by initiating new studies on the plant species distributions within the ranges of each species.

9319909 Anne Pusey In the past 30 years, Jane Goodall revolutionized our understanding of chimpanzee behavior, and in the process gave us an extraordinary perspective on ourselves and our behavioral origins. Chimpanzees are fascinating in their own right. They are one of the few mammalian species to show female dispersal and male-male cooperation, and this continuing study will provide new insights into the causes and consequences of this unusual social organization. Though less prominent than the chimp study, the Gombe baboon study is the longest and most extensive field study of any African monkey. This current research effort, in coordination with Goodall and Tanzanian collaborators, will involve three interconnecting projects. First, long-term demographic and behavioral data on chimpanzees and olive baboons will be analyzed and new data will be collected. This will include Goodall's records from the past three decades. The emphasis will be an examination of the costs and benefits of female dispersion and male sociality. In contrast, olive baboons show the social organization typical of old world monkeys, with home ranges maintained largely by the females and males moving between troops. This research effort will investigate group-level factors influencing female reproductive success, and the causes of individual variability in male reproductive success, social relationships and paternal care. The large sample sizes allow sophisticated statistical analysis of demography and social behavior. The second project involves a highly detailed survey of the diversity and distribution of vegetation in the entire park -- an area of unusual plant diversity. The vegetation studies will clarify the ecological basis of chimpanzee social organization, the importance of inter-troop competition in baboons, and will also contribute to the inventory of biodiversity in Tanzania. The third project will use DNA extracted from feces of both species to assess paternity, measure genetic relatedness and levels of inbreeding. By perfecting the extraction of nuclear DNA from feces and developing baboon-specific primers, the team will facilitate paternity studies in other primate field studies.

9507423 This project will use genetic analysis to determine the patterns of paternity and male reproductive success in the chimpanzees and baboons of Gombe National Park, Tanzania. These populations have been studied under the direction of Dr. Jane Goodall for 35 and 28 years, respectively. In both species, females mate with many males, and males show a variety of mating strategies including mating at high frequencies, aggressive competition for access to females, possessive behavior, the formation of consortships, and the cultivation of special relationships with females. However, little is known of the relative effectiveness of these strategies in achieving paternity because genetic analysis has not been possible. This project will use a non-invasive procedure, the extraction of DNA from feces, to obtain genetic material for analysis. Samples from 250 baboons in five troops, and 20 chimpanzees in one community, have already been collected, and techniques for DNA extraction have been perfected. Samples will be collected from additional infants and unsampled potential parents in six baboon troops and two chimpanzee communities to yield total sample sizes of 150 infant baboons and 20 infant chimpanzees. Approximately 8 hypervariable regions of the nuclear DNA will be amplified by the polymerase chain reaction (PCR), and paternity will be determined by comparing the genotypes of infants, their mothers, and potential fathers. In combination with the detailed behavioral records, knowledge of paternity will allow assessment of the effectiveness of different mating strategies. The study will provide new information about patterns mf relatedness within groups and will provide new insights into the evolution of competitive behavior and affiliative relationships in these species.

Animal Behavior Program
Nontechnical Abstract


Proposal #: 9817588
PI: Pusey, Anne
Title: Determinants of male dominance and reproductive success in wild primates



Male chimpanzees and baboons compete for dominance rank and for access to receptive females. The ultimate goal of the project is to determine how male reproductive success is influenced by such physical traits as body size, canine length and morphological symmetry and by such behavioral strategies as social dominance, alliance formation, paternal care and the cultivation of long-term relationships with females. Dr. Pusey's research will be carried out on the chimpanzees and baboons of Gombe National Park on populations that have been studied for nearly 40 years. This is an extraordinary database upon which to anchor interpretations of the results from this project. The immediate goal is to perfect techniques for paternity exclusions by extracting DNA from fecal samples and hair. Samples will be collected as part of the long-term studies at Gombe National Park, Tanzania. Various extraction techniques will be tested, and human MapPairTM primers will be screened to identify genetic markers in chimpanzees and baboons that exhibit necessary levels of heterozygosity yet whose alleles are sufficiently distinguishable from humans to minimize problems associated with contamination.

Measuring the relationship between physical prowess, symmetry, dominance rank, and reproductive success will increase understanding of the evolution of sexual dimorphism and the importance of symmetry in indicating "quality." Measuring the effects of behavioral strategies will reveal the extent to which male mating competition has driven the evolution of complex social behavior. Because these genetic techniques are non-invasive, the project will greatly enhance the ability to monitor levels of inbreeding in endangered populations.

Of the emerging infectious diseases, zoonotic and generalist viral pathogens pose a particular threat to public health and biodiversity. The effective control of these diseases requires both the identification of reservoires of infection and an understanding of viral transmission dynamics within complex host assemblages. Yet for most emerging infectious diseases, reservoirs remain to be identified and little is known about mechanisms by which infections are maintained. This study will propose a theoretical and practical framework for recognizing reservoirs in the field, which will be applied to identify reservoirs of viral infections in the Serengeti, Tanzania. The recent emergence of viral diseases in this area provides the opportunity for a comparative study of zoonotic and generalist pathogens within a diverse, well-studied and important ecosystem. Furthermore, the area is surrounded by rapidly expanding human and domestic animal populations which have profound impacts on the transmission dynamics of infectious diseases. This study will investigate the transmission dynamics of three viral pathogens, rabies, cane distemper virus (CDV), and canine parvovirus (CPV), identifying reservoirs of infection through a combination of approaches that include intervention trials, genetic analyses and disease surveillance. Empirical data on the spatial distribution of hosts and contact rated will be integrated into mathematical models of transmission between and within species. These models will be used to (a) investigate mechanisms by which viral infections are maintained in multi-population systems; (b) anticipate future requirements for disease management in relation to changes in human activity and climate patterns; (c) design cost-effective programs for the control of disease in human and animal populations.

The Greater Serengeti Ecosystem (hereafter "the Serengeti") is a complex coupled human and natural system consisting of a network of diverse and intense trophic interactions played out over a heterogeneous landscape. Livestock and a species-rich assemblage of large mammalian herbivores, the most abundant of which migrate over a 12,000 square-km area each year, consume a high fraction of primary plant production. These herbivores sustain human populations and a rich assemblage of avian and mammalian carnivores. Moreover, humans, wild animals, and livestock are all vulnerable to a wide variety of infectious diseases. Broad-scale heterogeneity in land use is superimposed on this dynamic landscape. The Serengeti National Park is a classic example of a protected area and ecotourism destination, while the adjacent Ngorongoro Conservation Area permits Maasai pastoralism, game reserves, (Maswa and Ikorongo) permit-controlled off-take of trophy species, and game-controlled areas (Grumeti) that permit all human activity except agriculture. The linkages between human and natural components of the Serengeti are so pervasive that human decision making may be the critical process governing the fate of the entire ecosystem. Pressure is mounting as human and animal populations converge on the western border of Serengeti National Park (SNP) and Mara Reserve. To study the coupling of natural ecosystem functioning and human decision making in the greater Serengeti, this interdisciplinary research project will use four modeling approaches: (1) Process-rich, spatially explicit ecosystem simulation models will be developed to predict changes in plant and animal communities as well as human use of landscapes at different scales. (2) Agent-based models will incorporate individual decision-making rules in a spatially explicit environment. (3) Analytical models of community modules will explore interactions among five to ten key species. (4) Macro-ecological models will describe system patterns and processes as functions of major resource inputs, such as rainfall and soil nutrients. These models will explore emergent dynamics of the Serengeti at various organizational scales. A large amount of Serengeti field data will be analyzed to parameterize the models and to assess their ability to explain past dynamics and current ecosystem trends. In addition, crucial new data on human activities and choices will be collected to understand the coupling of system dynamics between natural and human-dominated components. This blend of different modeling approaches and data syntheses will permit a unique integration of ecological and social sciences. The concept of ecosystem resilience/resistance will be directly related to the vulnerability of human societies.

The theory of complex systems proposes that emergent properties can arise from relatively simple underlying mechanisms propagated in space and time. The vulnerability of humans and sustainability of biodiversity in the Serengeti may be driven by a few critical constraints that operate independently of individual components. These constraints arise from fundamental laws/principles in psychology, biology, chemistry, and physics that constrain key biological processes and human decisions. Alternatively, complex systems may be sensitive to small differences in initial conditions and show a tendency to switch between alternative states. This sensitivity suggests that biodiversity and human welfare may be highly contingent on details such as individual behavior, the identity of the species participating, and the precise spatial arrangement of interactions among humans, plants, animals, and diseases. The Serengeti provides a unique opportunity to test this hypothesis, because its component parts are so conspicuous and its dynamical patterns have been measured for 40 years. Finally, emergent system properties may be contingent on just a few critical components, which would imply that the Serengeti can be understood from networks of interaction among a few key species of plants/animals and humans. In addition to providing fundamental new knowledge, the project will provide insights and information of immediate value of managers and decision makers in the study region and many other locales. It also will provide valuable research and training opportunities for students and post-doctoral scholars, and it will facilitate international collaborations between U.S. and African scientists. This project is supported by an award resulting from the FY 2003 special competition in Biocomplexity in the Environment focusing on the Dynamics of Coupled Natural and Human Systems.

Diseases that infect multiple species threaten the health of humans, domestic animals, and wildlife. This study addresses the disease dynamics of two multi-species diseases in the Serengeti ecosystem: canine distemper virus (which killed over a thousand lions in 1994) and rabies (which kills humans as well as all other mammals). The objective of this thesis is to use innovative models parameterized with field data on intraspecific and interspecific contact rates to understand how canine distemper virus and rabies persist in the Serengeti ecosystem and to design appropriate control measures. Mathematical models allow for virtual experiments that would otherwise be unethical or infeasible in the real world.

This research will be the first ecological study of disease dynamics in wild carnivores to combine modeling with detailed observations in a multi-host ecosystem. The theoretical models developed here will not only contribute to a basic understanding of disease dynamics but also provide practical recommendations for carnivore conservation and human health in rural Africa. Theoretical approaches to real-life conservation actions are urgently needed to improve future disease control programs in an era of frequent emerging diseases.

This project will conduct comprehensive research to construct and test detailed models of population and community ecology, with a focus on African lion populations. First, the project will investigate lion population dynamics at the level of individual social groups as well as larger-scale sub-populations, constructing statistical models with population-level, group-level, and individual variables to determine the relative impacts of short-term variability in demographic performance and environmental conditions on population growth and stability. Comprehensive data on day-to-day variation in prey availability within the ranges of 24 different lion groups will be measured and used to link the shifting mosaic of migratory herbivores and territorial behavior of the lions in a spatial food-web model across the landscape. Second, the project will investigate the role of spatial heterogeneity in stabilizing the coexistence of competing carnivore species. Cheetahs, leopards, lions and hyenas may show divergent niche strategies that create a reticulated pattern of occupancy within an overall pattern of coexistence. Third, the project will measure cycle-length of four viral diseases in the lions to test predictions of multi-host disease transmission models.

The project will continue to train Tanzanian researchers, collaborate with Tanzanian scientists and provide research opportunities for American graduate students and undergraduates, including individuals from under-represented minorities. Results from the study will help wildlife managers to predict consequences of habitat change and fragmentation, to identify the landscape features necessary for species co-existence, and to measure the effectiveness of disease control programs.

This project explores the population dynamics of large African predators, asking how spotted hyenas, leopards, and cheetahs are able to live with lions, given that lions frequently harass and kill these smaller predators. Investigators will integrate data from surveys of lions with data from camera traps to determine how hyenas, leopards, and cheetahs distribute themselves across the landscape with respect to lions, and how differences in habitat use enable these species to coexist with and without lions. Understanding how predators coexist is important for understanding how large ecosystems function. Recent research has emphasized the profound effects that top predators can have on ecosystems; disrupting predator populations can destabilize natural systems in unexpected ways. The ability to predict how and why destabilization occurs is a necessary first step to preventing the ecological collapse of ecosystems with many types of predators. This project will engage the public through a citizen science platform (www.SnapshotSerengeti.org) in which members of the public help identify wild animals in photographs taken by camera traps. As anthropogenic change drives the continued decline of large predators around the world, research on ecosystem stability becomes increasingly relevant, as does public engagement in research.

More specifically, this study will test predictions from an ongoing predator study in the Serengeti by comparing distributions and population sizes of spotted hyenas, leopards, and cheetahs across two South African reserves with and without lions. For example, without lions, leopard numbers may higher or hyenas may occupy prime riverine habitats. This type of response is expected because overlap between mammalian predators is typically minimal; instead, suppression appears to be mediated primarily through direct aggression and a large-scale avoidance response that displaces subordinate species from large portions of the landscape. In traditional predator-prey systems, this non-consumptive effect (NCE) of predation risk creates a "landscape of fear" that can be more important for predator-prey dynamics than actual predation. It can, for example, be the driving force behind trophic cascades. However, the role of NCEs in driving population dynamics has been almost exclusively investigated in small scale predator-prey systems. This project investigates the role of NCEs in driving apex-mesopredator coexistence in a guild of large African carnivores. The research has two aims: (1) to compare effects of large-scale displacement in driving lion-mesopredator coexistence, and (2) to evaluate the role of landscape structure and behavioral avoidance at multiple spatial and temporal scales in mediating lion-mesopredator coexistence. It is predicted that complex landscapes will facilitate fine-scale partitioning and thus coexistence by minimizing large-scale displacement.