Institute of Primate Research

Nairobi, Kenya

Institute of Primate Research

Nairobi, Kenya

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Snyder-Mackler N.,University of Pennsylvania | Alberts S.C.,Duke University | Alberts S.C.,Institute of Primate Research | Bergman T.J.,University of Michigan
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

By living in social groups with potential competitors, animals forgo monopolizing access to resources. Consequently, debate continues over how selection might favour sociality among competitors. For example, several models exist to account for the evolution of shared reproduction in groups. The 'concession model' hypothesizes that dominant reproducers benefit from the presence of subordinates, and hence tolerate some reproduction by subordinates. This mutual benefit to both dominants and subordinates may provide a foundation for the formation of social groups in which multiple members reproduce-a necessary step in the evolution of cooperation. To date, however, the concession model has received virtually no support in vertebrates. Instead, the vast majority of vertebrate data support 'limited control models', which posit that dominant reproducers are simply unable to prevent subordinates from reproducing. Here we present the most comprehensive evidence to date in support of the concession model in a vertebrate. We examined natural variation in the number of adult males in gelada (Theropithecus gelada) reproductive units to assess the extent of reproductive skew in multi-male units. Dominant ('leader') males in units that also had subordinate ('follower') males had a 30 per cent longer tenure than leaders in units that did not have followers, mainly because followers actively defended the group against potential immigrants. Follower males also obtained a small amount of reproduction in the unit, which may have functioned as a concession in return for defending the unit. These results suggest that dominants and subordinates may engage in mutually beneficial reproductive transactions, thus favouring male-male tolerance and cooperation. © 2012 The Royal Society.

Strum S.C.,Uaso Ngiro Baboon Project previously Gilgil Baboon Project | Strum S.C.,University of California at San Diego | Strum S.C.,Institute of Primate Research
International Journal of Primatology | Year: 2010

Ecosystems and habitats are fast becoming human dominated, which means that more species, including primates, are compelled to exploit new human resources to survive and compete. Primate "pests" pose major management and conservation challenges. I here present the results from a unique opportunity to document how well-known individuals and groups respond to the new opportunity to feed on human foods. Data are from a long-term study of a single population in Kenya at Kekopey, near Gilgil, Kenya. Some of the naïve research baboons became raiders while others did not. I compare diet, activity budgets, and home range use of raiders and nonraiders both simultaneously, after the incursion of agriculture, and historically compared to the period before agriculture appeared. I present measures of the relative benefits (female reproduction) and costs (injuries, mortality, and survivorship) of incorporating human food into the diet and discuss why the baboons raid and their variations in raiding tendencies. Guarding and chasing are evaluated as control techniques. I also suggest conflict mitigation strategies by identifying the most likely options in different contexts. I end with a proposal for a rapid field assessment of human wildlife conflict involving primates. © The Author(s) 2009.

Babbitt C.C.,Duke University | Tung J.,Duke University | Wray G.A.,Duke University | Alberts S.C.,Duke University | Alberts S.C.,Institute of Primate Research
Genome Biology and Evolution | Year: 2012

Changes in gene expression during development play an important role in shaping morphological and behavioral differences, including between humans and nonhuman primates. Although many of the most striking developmental changes occur during early development, reproductive maturation represents another critical window in primate life history. However, this process is difficult to study at the molecular level in natural primate populations. Here, we took advantage of ovarian samples made available through an unusual episode of human-wildlife conflict to identify genes that are important in this process. Specifically, we used RNA sequencing (RNA-Seq) to compare genome-wide gene expression patterns in the ovarian tissue of juvenile and adult female baboons from Amboseli National Park, Kenya. We combined this information with prior evidence of selection occurring on two primate lineages (human and chimpanzee). We found that in cases in which genes were both differentially expressed over the course of ovarian maturation and also linked to lineage-specific selection this selective signature was much more likely to occur in regulatory regions than in coding regions. These results suggest that adaptive change in the development of the primate ovary may be largely driven at the mechanistic level by selection on gene regulation, potentially in relationship to the physiology or timing of female reproductive maturation. © The Author(s) 2011.

Snyder-Mackler N.,Duke University | Alberts S.C.,Duke University | Alberts S.C.,Institute of Primate Research | Bergman T.J.,University of Michigan
Molecular Ecology | Year: 2014

Multilevel societies with fission-fusion dynamics - arguably the most complex animal societies - are defined by two or more nested levels of organization. The core of these societies are modular social units that regularly fission and fuse with one another. Despite convergent evolution in disparate taxa, we know strikingly little about how such societies form and how fitness benefits operate. Understanding the kinship structure of complex societies could inform us about the origins of the social structure as well as about the potential for individuals in these societies to accrue indirect fitness benefits. Here, we combined genetic and behavioural data on geladas (Theropithecus gelada), an Old World Monkey, to complete the most comprehensive socio-genetic analysis of a multilevel society to date. In geladas, individuals in the core social 'units', associate at different frequencies to form 'teams', 'bands' and, the largest aggregations, 'communities'. Units were composed of closely related females, and females remained with their close kin during permanent fissions of units. Interestingly, female-female relatedness also significantly predicted between-unit, between-team and between-band association patterns, while male-male relatedness did not. Thus, it is likely that the socio-genetic structure of gelada society results from females maintaining associations with their female relatives during successive unit fissions - possibly in an attempt to balance the direct and indirect fitness benefits of group living. Overall, the persistence of associations among related females across generations appears to drive the formation of higher levels of gelada society, suggesting that females seek kin for inclusive fitness benefits at multiple levels of gelada society. © 2014 John Wiley & Sons Ltd.

Alberts S.C.,Duke University | Alberts S.C.,Institute of Primate Research | Fitzpatrick C.L.,Duke University
Behavioral Ecology | Year: 2012

The exaggerated sexual swellings exhibited by females of some primate species have been of interest to evolutionary biologists since the time of Darwin. We summarize existing hypotheses for their function and evolution and categorize these hypotheses within the context of 3 types of variation in sexual swelling size: 1) variation within a single sexual cycle, 2) variation between the sexual cycles of a single female, and 3) differences between females. We then propose the Paternal Care Hypothesis for the function of sexual swellings, which posits that exaggerated sexual swellings function to elicit the right quantity and quality of male care for a female's infant. As others have noted, swellings may allow females to engender paternity confusion, or they may allow females to confer relative paternal certainty on one male. Key to our hypothesis is that both of these scenarios create an incentive for one or more males to provide care. This hypothesis builds on previous hypotheses but differs from them by highlighting the elicitation of paternal care as a key function of swellings. Our hypothesis predicts that true paternal care (in which males accurately differentiate and provide assistance to their own offspring) will be most common in species in which exaggerated swellings accurately signal the probability of conception, and males can monopolize females during the window of highest conception probability. Our hypothesis also predicts that females will experience selection to behave in ways that either augment paternity confusion or enhance paternal certainty depending on their social and demographic contexts. © 2012 The Author.

Foerster S.,Columbia University | Foerster S.,Institute of Primate Research | Monfort S.L.,Smithsonian Conservation Biology Institute
Hormones and Behavior | Year: 2010

Because of their mediating role in the stress response and potential effects on fitness, glucocorticoid (GC) hormones are increasingly used to assess the physiological costs of environmental and behavioral variation among wild vertebrates. Identifying the proximate causes of GC variation, however, is complicated by simultaneous exposure to multiple potentially stressful stimuli. Here, we use data from a partially provisioned social group of Sykes' monkeys to evaluate the effects of potential psychological and metabolic stressors on temporal and individual variation in fecal GC (fGC) excretion among 11 adult females. Despite high rates of agonism over provisioned foods fGCs declined during periods of high provisioning frequency when fruit availability was dominated by neem (Azadirachta indica), an item requiring great feeding effort. Provisioned foods did not prevent fGC increases when availability of the most preferred main fruit item, tamarind (Tamarindus indica), declined drastically. Although rank-related differences in access to provisioned foods and rates of agonism did not lead to an overall effect of rank on fGCs, low-ranking females excreted more fGCs than high-ranking females during a period of high provisioning intensity and low fruit availability. The emergence of this rank effect was associated with elevated feeding effort in all females, a greater access to provisioned items by high-ranking females, and a higher proportion of time spent moving in low-ranking females. Our findings suggest that metabolic stressors were the primary determinants of both temporal and individual variation in fGCs, indicating potential fitness benefits for high-ranking females when food availability is limited. © 2010 Elsevier Inc.

Foerster S.,Columbia University | Foerster S.,Institute of Primate Research | Cords M.,Columbia University | Monfort S.L.,Smithsonian Conservation Biology Institute
PLoS ONE | Year: 2012

Animals facing seasonal variation in food availability experience selective pressures that favor behavioral adjustments such as migration, changes in activity, or shifts in diet. Eclectic omnivores such as many primates can process low-quality fallback food when preferred food is unavailable. Such dietary flexibility, however, may be insufficient to eliminate constraints on reproduction even for species that live in relatively permissive environments, such as moist tropical forests. Focusing on a forest-dwelling primate with a flexible diet (Cercopithecus mitis) we investigated whether females experience seasonal energetic stress and how it may relate to reproductive seasonality. We used fecal glucocorticoids (fGCs) as an indicator of energetic stress, controlling for the potentially confounding effects of social interactions and reproductive state. We modeled within-female fGC variation with General Linear Mixed Models, evaluating changes in feeding behavior and food availability as main effects. Regardless of reproductive state, fGCs increased when females shifted their diet towards fallback foods (mature leaves and other non-preferred items) and when they spent more time feeding, while fGCs decreased with feeding time on preferred items (insects, fruits, young leaves) and with the availability of young leaves. Changes in fruit availability had no general effects on fGCs, likely because fruits were sought out regardless of availability. As predicted, females in the energetically demanding stages of late pregnancy and early lactation showed greater increases in fGCs between periods of low versus high availability of fruits and young leaves than females in other reproductive states. Potential social stressors had no measurable effects on fGCs. Preliminary evidence suggests that seasonal energetic stress may affect the timing of infant independence from mothers and contribute to unusually long inter-birth intervals compared to closely related species of similar body size. Our findings highlight how the study of stress responses can provide insights into the proximate control of reproductive strategies. © 2012 Foerster et al.

Wolfaardt M.,University of Pretoria | Kiulia N.M.,Institute of Primate Research | Mwenda J.M.,Institute of Primate Research | Taylor M.B.,University of Pretoria | Taylor M.B.,National Health Laboratory Service Tshwane Academic Division
Journal of Clinical Microbiology | Year: 2011

A human astrovirus (HAstV) strain from Kenya was characterized by nucleotide sequence analysis. Sequences from open reading frame 1a (ORF1a) clustered with genotype 6/7, those from ORF1b clustered with genotype 3, and those from ORF2 clustered with genotype 2. A recombination point in the ORF1b-ORF2 junction was identified, with a second possible recombination point within the ORF1a region. Copyright © 2011, American Society for Microbiology. All Rights Reserved.

Obiero J.,Institute of Primate Research | Obiero J.,University of Nairobi | Mwethera P.G.,Institute of Primate Research | Hussey G.D.,University of Cape Town | Wiysonge C.S.,University of Cape Town
BMC Infectious Diseases | Year: 2012

Background: Each year more than two million people are newly infected with HIV worldwide, a majority of them through unprotected vaginal sex. More than half of new infections in adults occur in women. Male condoms and male circumcision reduce the risk of HIV acquisition; but the uptake of these methods is out of the control of women. We therefore aimed to determine the effectiveness of vaginal microbicides (a potential female-controlled method) for prevention of sexual acquisition of HIV in women.Methods: We conducted a comprehensive search of peer-reviewed and grey literature for publications of randomised controlled trials available by September 2012. We screened search outputs, selected studies, assessed risk of bias, and extracted data in duplicate; resolving differences by discussion and consensus.Results: We identified 13 eligible trials that compared vaginal microbicides to placebo. These studies enrolled 35,905 sexually active HIV-negative women between 1996 and 2011; in Benin, Cameroon, Cote d'Ivoire, Ghana, Kenya, Malawi, Nigeria, South Africa, Tanzania, Uganda, Zambia, Zimbabwe, India, Thailand, and the United States of America. A small trial of 889 women found that tenofovir (a nucleotide reverse transcriptase inhibitor) significantly reduces the risk of HIV acquisition (risk ratio [RR] 0.63, 95% confidence intervals [CI] 0.43 to 0.93). Effectiveness data are not yet available from follow-up tenofovir trials being conducted in South Africa, Uganda, and Zimbabwe (1 trial) and multiple sites in South Africa (1 trial). We found no evidence of a significant effect for nonoxynol-9 (5 trials), cellulose sulphate (2 trials), SAVVY (2 trials), Carraguard (1 trial), PRO 2000 (2 trials), and BufferGel (1 trial) microbicides. The pooled RR for the effect of current experimental vaginal microbicides on HIV acquisition in women was 0.97, 95%CI 0.87 to 1.08. Although study results were homogeneous across the different drug classes (heterogeneity P = 0.17, I2 = 27%), the overall intervention effect was not statistically significant. Nonoxynol-9 significantly increased the risk of having adverse genital lesions but no other microbicide led to significant increases in adverse events.Conclusions: There is not enough evidence at present to recommend vaginal microbicides for HIV prevention. Further high-quality research is needed to confirm the beneficial effects of tenofovir as well as continue the development and testing of new microbicides. © 2012 Obiero et al.; licensee BioMed Central Ltd.

News Article | November 2, 2016

Approximately 11% of women worldwide suffer from premature ovarian failure. This can have many different causes: chemotherapy administered for a malignant disease might irreversibly damage the ovaries and, because of the advances in modern cancer therapy, the number of young women surviving cancer is on the increase. The women, some of whom are still very young, prematurely enter menopause. Genetic diseases can also trigger early menopause but, in most cases, no specific cause can be identified. Now, for the first time, an international team of researchers led by MedUni Vienna has successfully transplanted an ovary from one individual to another, even managing to restore a monthly cycle. "Firstly, an early menopause means that women cannot fulfil their longing for a child and, secondly, the associated drop in hormone levels can prematurely trigger osteoporosis or other menopausal complications," explains Michael Feichtinger, lead author of the study from MedUni Vienna's Department of Obstetrics and Gynecology. Also taking part in the study are experts in preserving fertility, Samuel Kim from the University of Kansas School of Medicine and Mats Brännström from the University of Gothenburg. In the autumn of 2014, the latter successfully performed the first series of successful womb transplants in the world. Using an animal model, the researchers have now attempted, for the first time, to perform an allogeneic ovary transplant (from one individual to another) -- and this was done with the aid of a new immunosuppressive agent known as PIF (preimplantation factor). This was done at the World Health Organisation (WHO) Institute of Primate Research in Nairobi (Kenya), using two baboons. They were treated with PIF both before and after transplantation. The outcome: the transplant was successful in one of the animals, a functional monthly cycle was initiated -- however it was not successful in the other. Feichtinger: "Notwithstanding this, the study is still very promising. These results would suggest that successful ovarian transplantation might be possible in future. The researchers also demonstrated that the new immunosuppressive agent PIF functions well without side-effects and this could open up new potential applications for other types of transplant procedure." Further studies are being conducted to demonstrate precisely which factors are important in ensuring the success of the transplant. The results of this study were presented at the world's largest reproduction conference in Salt Lake City at the end of October. Michael Feichtinger's lecture was one of six "late breaking abstracts" and immediately preceded John Zhang's lecture on his sensational technique known as the "three-parent method," in which the nucleus of an ovum was transferred into an enucleated donor ovum. It was just at the end of September that a baby was born from two different ova, as a result of this technique.

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