Papio Cynocephalus Research Articles

Primate census and habitat evaluation in the Tana delta region, Kenya

AbstractNineteen indigenous forest patches in the Tana River delta region, Kenya were surveyed between October and November 2000 for primates and habitat disturbance. Special emphasis was placed on the endangered Tana River red colobus (Procolobus rufomitratus Peters) and crested mangabeys (Cercocebus galeritus galeritus Peters), both of which are endemic to the region. Habitat disturbances evident in the forests included cutting of trees, harvesting of thatching material, firewood collection, dyke construction, cultivation, palm wine tapping and charcoal burning. A total of 85 groups of five primate species were counted. These comprised eighteen, ten, 22, 31 and four groups of red colobus, crested mangabey, baboons (Papio cynocephalus L.), sykes monkeys (Cercopithecus mitis Wolf) and vervet monkeys (Cercopithecus aethiops L.), respectively. A wider distribution of red colobus and crested mangabeys than was documented previously was noted, implying that they are probably more abundant than hitherto reported. It is hypothesized that extensive studies on some fauna considered endangered world‐wide would probably redefine their conservation status. Future studies in the lower Tana River region should cover the previously unsurveyed forests and focus on ways of curbing forest destruction.

Female Baboons’ Responses to Male Loud Calls

AbstractMale baboons (Papio cynocephalus ursinus) give loud, two‐syllable ‘wahoo’ calls in response to predators (alarm wahoos) and during aggressive displays that may include multiple males chasing each other or females (contest wahoos). Although acoustic analysis has revealed significant differences between the two calls, these differences are subtle and the two subtypes can be difficult for humans to distinguish. Whatever the evolutionary mechanisms that might have acted on the production of acoustically graded loud calls, it would seem to be adaptive for listeners to discriminate among calls that are given in qualitatively different contexts. This is particularly true in the case of female baboons. Alarm wahoos, which are given during predator encounters, demand qualitatively different responses from contest wahoos, which are given in contexts when females are at risk of harassment and infanticide by males. In playback experiments, females responded for significantly longer durations to alarm than to contest wahoos. Moreover, only alarm wahoos caused females to flee. Despite their acoustic similarity, female baboons appear to associate alarm and contest wahoos with qualitatively different events.

Production of procalcitonin (PCT) in non-thyroidal tissue after LPS injection.

Procalcitonin (PCT) is one of the precursors in the synthesis of calcitonin in thyroidal C-cells and other neuroendocrine cells. PCT, among other calcitonin precursors, is elevated in the serum of many conditions associated with a systemic inflammatory response syndrome, even in the absence of the thyroid gland. The aim of our study was to identify PCT-producing extrathyroidal tissues in primate sepsis. In order to induce PCT production, we treated four olive baboons ( papio cynocephalus anubis) with the endotoxin lipopolysaccharide (LPS) from s. typhimurium. We found an increase in serum PCT 3 to 5 hours after LPS injection to levels of 0.2 ng/ml, attaining a peak above 4 ng/ml PCT at 10 hours. In contrast, the untreated baboon had no detectable circulating PCT in the serum. In one animal, additional LPS boosting after 24 hours did not increase serum PCT further. Soluble proteins were extracted from different organs, fractionated by C18 extraction, and PCT was measured in an immunoluminometric assay (ILMA), which was specifically developed for this study. PCT concentrations above 0.2 ng/g of wet tissue were found in a variety of organs in LPS treated baboons, but not in the control baboon. Organs and tissues with the highest PCT concentration included liver, kidney, aorta, fat, ovaries, bladder and adrenal gland. RT-PCR confirmed an extrathyroidal origin of PCT. Importantly, CT-mRNA expression was found in liver, lung, kidney, adrenal, colon, skin, spleen, brain and pancreas. In conclusion, our data confirm previous findings in hamsters, indicating an extrathyroidal origin for PCT in sepsis. Our primate model offers a valuable tool for further investigation of PCT's pathophysiological role and its immunoneutralization as a therapy for sepsis.

Concentrations of four fecal steroids in wild baboons: short-term storage conditions and consequences for data interpretation

One source of both bias and “noise” in fecal steroid analysis is temporal change in steroid concentrations resulting from duration or conditions of fecal sample storage. However, no consensus currently exists regarding correct procedures or precautions necessary for fecal sample storage, and conditions vary widely within field endocrinology literature. This study considered the effects of short-term, weeks-long, storage conditions on quantifiable fecal testosterone (fT), glucocorticoids (fGC), estrogens (fE), and progestagen (fP) metabolite concentrations in wild baboons ( Papio cynocephalus). Quadruplicate subsamples of fecal samples ( n=29) collected at Amboseli National Park and its environs were subjected to four different storage conditions prior to lyophilization, in order to determine the effects of storage on subsequent steroid concentrations, as assessed by 125 I radioimmunoassays. As expected, the best alternative to the “initial condition” of lyophilization at three days after collection was to freeze fecal samples at −20 °C for two weeks prior to lyophilization. This storage method resulted in no significant change from initial steroid concentrations for fE, fT, or fP, although fGC showed a slight but significant decline. Storage for two weeks in a charcoal refrigerator caused a mean increase in all four steroid concentrations. However, the results from this storage condition were robust in terms of practical questions asked of the data: fE and fP values still reflected pregnant versus non-pregnant states in baboon females; a fGC profile constructed by age class resembled that created from the samples from the initial condition, although slightly inflated across age classes; and there were only moderate changes in relative fT concentrations across adult males. Knowledge of the effects of storage upon each steroid analyzed within one’s study is a necessary component in determining the optimal compromise for storage protocol in a particular research project.

Queuing and queue-jumping: long-term patterns of reproductive skew in male savannah baboons, Papio cynocephalus

In many animals, variance in male mating success is strongly correlated with male dominance rank or some other measure of fighting ability. Studies in primates, however, have varied greatly in whether they detect a relationship between male dominance rank and mating success. This variability has led to debate about the nature of the relation between rank and mating success in male primates. We contribute to the resolution of this debate by presenting an analysis of the relationship between dominance rank and male mating success over 32 group-years in a population of wild savannah baboons. When data were pooled over the entire period, higher-ranking males had greater access to fertile females. However, when we examined successive 6-month blocks, we found variance in the extent to which rank predicted mating success. In some periods, the dominance hierarchy functioned as a queue in which males waited for mating opportunities, so that rank predicted mating success. In other periods, the queuing system broke down, and rank failed to predict mating success when many adult males were in the group, when males in the group differed greatly in age, and when the highest-ranking male maintained his rank for only short periods. The variance within this single population is similar to the variance observed between populations of baboons and between species of primates. Our long-term results provide strong support for the proposition that this variance is not an artefact of methodological differences between short-term studies, but is due to true variance in the extent to which high-ranking males are able to monopolize access to females. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.

Day length, latitude and behavioural (in)flexibility in baboons (Papio cynocephalus ursinus)

Annual cycles in day length are an important consideration in any analysis of seasonal behaviour patterns, since they determine the period within which obligate diurnal or nocturnal animals must conduct all of their essential activities. As a consequence, seasonal variation in day length may represent an ecological constraint on behaviour, since short winter days restrict the length of the time available for foraging in diurnal species (with long summer days, and thus short nights, a potential constraint for nocturnal species). This paper examines monthly variation in activity patterns over a 4-year study of chacma baboons (Papio cynocephalus ursinus) at De Hoop Nature Reserve, South Africa. Time spent feeding, moving, grooming and resting are all significant positive functions of day length, even before chance events such as disease epidemics and climatically mediated home range shifts have been accounted for. These results provide strong support for the idea that day length acts as an ecological constraint by limiting the number of daylight hours and thus restricting the active period at certain times of year. Day length variation also has important implications across populations. Interpopulation variation in resting time, and non-foraging activity in general, is a positive function of latitude, with long summer days at temperate latitudes apparently producing an excess of time that cannot profitably be devoted to additional foraging or social activity. However, it is the short winter days that are probably of greatest importance, since diurnal animals must still fulfil their foraging requirements despite the restricted number of daylight hours and elevated thermoregulatory requirements at this time of year. Ultimately this serves to restrict the maximum ecologically tolerable group sizes of baboon populations with increasing distance from the equator. Seasonal variation in day length is thus an important ecological constraint on animal behaviour that has important implications both within and between populations, and future studies at non-equatorial latitudes must clearly be mindful of its importance.

Loud calls as indicators of dominance in male baboons (Papio cynocephalus ursinus)

Adult male baboons (Papio cynocephalus) give loud two-syllable 'wahoo' calls during dawn choruses, interactions between groups, when chasing females, and in aggressive interactions with other males. These 'contest' wahoos are acoustically different from 'alarm' wahoos given to predators. In a study of free-ranging baboons in the Okavango Delta, Botswana, we found no significant correlations between the acoustic features of wahoos and adult male size; however, acoustic features were correlated with male dominance rank, age, and calling bout length. Here we show that other measures of calling behavior also appear to function as honest indicators of stamina and competitive ability. High-ranking males were more likely than middle- or low-ranking males to participate in wahoo bouts. They called at significantly higher rates, and their bouts were longer and contained more calls. All males were significantly more likely to participate in wahoo bouts with another male if their opponent's rank was similar to their own. Bouts involving males of similar ranks were longer, contained more wahoos, and involved calling at higher rates, than other bouts. In contests between males of similar ranks, the subordinate and dominant were equally likely to end the bout, whereas in contests involving males of disparate ranks, subordinates were significantly more likely to end the bout. Bouts involving males of similar rank were significantly more likely than others to escalate and result in physical fighting.

Analysis of porous ingrowth in intervertebral disc prostheses: a nonhuman primate model.

A study was conducted to investigate the biomechanical, histochemical, and biologic ingrowth characteristics of the most widely used total disc prosthesis, the hydroxyapatite-coated SB Charité prosthesis. To compare the porous ingrowth, linear apposition, or bony ingrowth in total disc replacement with published reports of porous ingrowth prostheses in the appendicular skeleton. Seven mature baboons (Papio cynocephalus) underwent L5-L6 total disc replacement through an anterior transperitoneal approach. The SB Charité prosthetic vertebral endplates (n = 14) were cobalt-chrome covered by two layers of thin titanium with a hydroxyapatite coating, which was electrochemically bonded to the implant surface. At 6 months after surgery, the range of motion exhibited by the SB Charité and the nonoperative control subjects under axial compression, flexion-extension, and lateral bending showed no statistical difference (P > 0.05). Plain film radiographic analysis showed no lucencies or loosening of any prosthetic vertebral endplate. Gross histopathologic analysis of the hydroxyapatite-coated SB Charité prosthesis demonstrated excellent ingrowth at the level of the implant-bone interface, without evidence of fibrous tissue or synovium. Histochemical assays showed no accumulation of particulate wear debris (no titanium, ultrahigh molecular weight polyethylene, or cobalt-chrome) nor cytokines (tumor necrosis factor-alpha, prostaglandin E2, interleukin-1, -2, or -6). Total endplate area showed a mean ingrowth (volume fraction) of 47.9% +/- 9.12% and a total ingrowth range of 35.5% to 58.8%. The porous ingrowth (percentage of pore ingrowth coverage at the bone-metal interface) was more favorable for total disc replacement than for cementless total joint components in the appendicular skeleton (range, 10-30%). The reason for the improved degree of porous ingrowth in total disc replacement prostheses probably is that ligamentotaxis causes sustained compression across the metal-bone interface.

Increased virus replication and virulence after serial passage of human immunodeficiency virus type 2 in baboons.

Similar to human immunodeficiency virus type 1 (HIV-1) infection of humans, the natural history of HIV-2 infection in baboons (Papio cynocephalus) is a slow and chronic disease that generally takes several years before an AIDS-like condition develops. To shorten the amount of time to the development of disease, we performed five serial passages of HIV-2(UC2) in baboons by using blood and bone marrow samples during the acute phase of infection when viral loads were at high levels. After these serial passages, virus levels in plasma, peripheral blood mononuclear cells (PBMC) and lymphatic tissues in the acutely infected baboons were increased. Within 1 year of the HIV-2 infection, all of the inoculated baboons showed specific signs of AIDS-related disease progression within the lymphatic tissues, such as vascular proliferation and lymphoid depletion. The HIV-2(UC2) recovered after four serial passages showed increased kinetics of viral replication in baboon PBMC and cytopathicity. This study suggests that the HIV-2 isolate recovered after several serial passages in baboons will be useful in future studies of AIDS pathogenesis and vaccine development by using this animal model.

Gastrointestinal Parasites in Free-Ranging Kenyan Baboons (Papio cynocephalus and P. anubis)

We screened fecal samples from 3 groups of wild-living baboons (Papio cynocephalus and P. anubis), involved in longitudinal behavioral studies, for evidence of gastrointestinal parasites. The two objectives of the study were: 1) to compare parasites from two of the groups with different foraging behavior from the same area and 2) to obtain fecal parasitic data on 3 groups of baboons to provide baseline reference data. We sampled individual baboons opportunistically from Lodge and Hook's groups, Amboseli National Park and from Mpala Group, Mpala Wildlife Research Centre, Kenya. Lodge Group baboons supplemented foraging on wild foods by daily foraging in human-source refuse, whereas Hook's and Mpala groups did not. We collected fecal samples from 55, 30 and 42 individuals in Hook's, Lodge and Mpala groups, respectively, and processed them via ether sedimentation. We identified strongylids, Streptopharagus sp., Physaloptera sp., Trichuris sp., Enterobius sp., and Strongyloides sp., in the feces, but no parasite directly attributable to exposure to people. Garbage- and wild-feeding Amboseli baboons differed in the prevalence of Streptopharagus sp., Physaloptera sp. and Trichuris sp.

Sero-epizootiologic survey of Trypanosoma brucei in Kenyan nonhuman primates.

Blood samples were collected from 121 individuals of three species of wild-caught nonhuman primates from Kenya, including African green monkeys (Cercopithecus aethiops), Syke's monkeys (C. mitis), and olive baboons (Papio cynocephalus anubis), and were examined for circulating Trypanosoma brucei and for T. brucei antigen and anti-trypanosome antibody. Indirect antibody enzyme-linked immunosorbent assay detected titers of anti-T. brucei antibodies in 13 of the primates sampled, and field-oriented latex agglutination test detected invariant T. brucei antigens in 10 (8.3%) of the primates. However, no trypanosomes were visible in blood smears, on wet blood films, or by buffy coat technique, nor were they demonstrable in a subset of C. aethiops individuals that were studied using mouse subinoculation.

Genetic evidence for long-term population decline in a savannah-dwelling primate: inferences from a hierarchical bayesian model.

The purpose of this study was to test for evidence that savannah baboons (Papio cynocephalus) underwent a population expansion in concert with a hypothesized expansion of African human and chimpanzee populations during the late Pleistocene. The rationale is that any type of environmental event sufficient to cause simultaneous population expansions in African humans and chimpanzees would also be expected to affect other codistributed mammals. To test for genetic evidence of population expansion or contraction, we performed a coalescent analysis of multilocus microsatellite data using a hierarchical Bayesian model. Markov chain Monte Carlo (MCMC) simulations were used to estimate the posterior probability density of demographic and genealogical parameters. The model was designed to allow interlocus variation in mutational and demographic parameters, which made it possible to detect aberrant patterns of variation at individual loci that could result from heterogeneity in mutational dynamics or from the effects of selection at linked sites. Results of the MCMC simulations were consistent with zero variance in demographic parameters among loci, but there was evidence for a 10- to 20-fold difference in mutation rate between the most slowly and most rapidly evolving loci. Results of the model provided strong evidence that savannah baboons have undergone a long-term historical decline in population size. The mode of the highest posterior density for the joint distribution of current and ancestral population size indicated a roughly eightfold contraction over the past 1,000 to 250,000 years. These results indicate that savannah baboons apparently did not share a common demographic history with other codistributed primate species.

Forage quality and the costs of lactation for female gelada baboons

Field studies of two species of baboons suggest that Altmann's model of maternal time budgets (1980, Baboon Mothers and Infants, Cambridge, Massachusetts: Harvard University Press) provides a good qualitative but a poor quantitative fit to observed changes in the time that mothers spend feeding across infant age. We suggest that the poor quantitative fit might be explained by the fact that food quality varies across time, so that females are forced to feed for longer to gain the same nutrient intake when quality is poor. The hypothesis was tested with data from both gelada baboons,Theropithecus gelada , and Altmann's own baboons, Papio cynocephalus, with rainfall and ambient temperature as indices of vegetation nutritional quality. The results confirm that a three-factor model incorporating infant age, rainfall in the 2 preceding months and current ambient temperature provides a significantly improved fit to the observed data. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Total disc replacement arthroplasty using the AcroFlex lumbar disc: a non-human primate model.

Using a non-human primate model, the current study was undertaken to investigate the efficacy of the AcroFlex lumbar disc as an intervertebral disc prosthesis, based on biomechanical, histopathologic and histomorphometric analyses. A total of 20 mature male baboons (Papio cynocephalus, mean weight 30 kg) were randomized into two equal groups based on post-operative time periods of 6 (n=10) and 12 months (n=10). Each animal underwent an anterior transperitoneal surgical approach to the lumbar spine, with intervertebral reconstructions performed at L3-L4 and L5-L6 using the following techniques: (1) tricortical iliac autograft and (2) AcroFlex lumbar disc. The two treatments were equally randomized between the non-contiguous operative lumbar levels. Post-mortem analysis included histopathologic assessment of the systemic reticuloendothelial tissues, multi-directional flexibility testing of the operative functional spinal units and quantitative histological analysis of trabecular bone coverage at the prosthesis endplates. Data were statistically compared using a one-way ANOVA with the Student-Newman-Keuls test. All animals survived the operative procedure and post-operative interval without significant intra- or peri-operative complications. Histopathologic analysis of the paraffin-embedded systemic reticuloendothelial tissues indicated no significant pathologic changes at the 6- or 12-month intervals. Plain film radiographic analysis showed no lucencies or loosening of any prosthetic vertebral endplate. Biomechanical testing of the 6-month autograft, reconstructions with AcroFlex lumbar disc and non-operative control (n=10) intact motion segments indicated no significant differences in peak range of motion (ROM) in axial compression. However, axial rotation produced significantly lower ROM for the autograft treatment compared to the intact and AcroFlex groups (P<0.05). The most significant differences in peak ROM were noted between all treatment groups under flexion/extension and lateral bending loading modalities (P<0.05). By 12 months, the intact condition indicated significantly more motion in all bending modes compared to the AcroFlex and autograft treatments, which were not statistically different from each other (P>0.05). Gross histopathologic analysis of the AcroFlex disc prosthesis demonstrated excellent ingrowth at the level of the implant-bone interface, without evidence of fibrous tissue or synovium. BioQuant histomorphometric analysis at the metal-bone interface (bone contact area/total endplate area) indicated the mean ingrowth was 54.59+/-13.24% at 6 months and 56.79+/-5.85% at 12 months. Radiographic analysis showed no lucencies or loosening of the AcroFlex vertebral endplate. Based on multi-directional flexibility testing, motion was preserved in axial rotation, but significantly diminished in the other bending modalities, particularly at the 12-month interval. This effect may be secondary to the limited surface area of device-vertebral endplate contact. Histomorphometric analysis of porous ingrowth coverage at the vertebral bone-metal interface was more favorable for total disc arthroplasty compared to historical reports of cementless femoral components. This project serves as the first comprehensive in vivo investigation into the AcroFlex disc prosthesis, and establishes an excellent research model in the evaluation of total disc replacement arthroplasty.

A matter of time: evaluating the storage of fecal samples for steroid analysis

The extraction and immunoassay of fecal steroids is an increasingly common technique, used in both captive and field studies to provide an approximation of an animal’s circulating concentration of hormones through non-invasive methods. Storage of fecal samples is of critical concern because fecal bacteria metabolize fecal steroids within hours after deposit. Ethanol is often used as a preservative for fecal samples stored for several hours at room temperature. We examined the stability of fecal estrogen (fE) and glucocorticoid (fGC) metabolites from baboon ( Papio cynocephalus) samples in a 95% ethanol solution at ambient temperature and at −20 °C over the course of six months, to determine the effect of storage on steroid concentrations. As measured by radioimmunoassay, fE metabolite concentrations increased by 122% at 90 days and fGC metabolite concentrations increased by 92% at 120 days. After peaking, both hormones declined to near initial concentrations by 180 days in ambient temperature samples. In samples stored at sub-zero temperatures, fGC metabolite concentrations showed a similar but dampened pattern, while fE metabolite concentrations exhibited small and variable changes with no consistent trend. We discuss explanations for the dynamic pattern of changing fecal metabolite concentrations and offer practical and analytical guidance to field workers for situations in which ideal conditions for stabilizing hormones are not available.

Structural analysis of human CCR2b and primate CCR2b by molecular modeling and molecular dynamics simulation.

CCR2b, a chemokine receptor for MCP-1, -2, -3, -4, plays an important role in a variety of diseases involving infection, inflammation, and/or injury, as well as being a coreceptor for HIV-1 infection. Two models of human CCR2b (hCCR2b) were generated by homology modeling and 1 ns restrained molecular dynamics (MD) simulation. In one only C113-C190 forms a disulfide bond (SS model); in another the potential C32-C277 disulfide bond was formed (2SS model). Analysis of the structures and averaged displacements of Calpha atoms of the N-terminal residues shows that the main differences between the SS and 2SS models lie in a region D25YDYGAPCHKFD36; in the extracellular part of the 2SS model the accessible surfaces of N12, F23, Y26, Y28 and F35 are obviously raised and a more stable H-bond net is formed. The potential energy of the 2SS-water assembly finally fluctuated around -43,020 kJ x mol(-1), which is about 302 kJ x mol(-1) lower than that of the SS-water assembly. All these results suggest that the 2SS model is more favorable. The CCR2b genes of 17 primates were sequenced and four CCR2b models for primates Ateles paniscus (A. pan), Hylobates leucogyneus(H. leu), Papio cynocephalus (P. cyn) and Trachypithecus francoist ( T. fra) were generated based on the 2SS model. A comparison of hCCR2b with primate CCR2b also supports the importance of the region D25YDYGAPCHKFD36. Electrostatic potential maps of human and primate CCR2b all display the dipolar characteristics of CCR2b with the negative pole located in the extracellular part and a strong positive pole in the cytoplasmic part. Based on the CCR2b model, we suggest that the main functional residues fall in the D25YDYGAPCHKFD36 region, and the negative electrostatic feature is a non-specific, but necessary, factor for ligands or gp120/CD4 binding.

Out of the mouths of baboons: stress, life history, and dental development in the Awash National Park hybrid zone, Ethiopia.

The techniques of dental histology provide a method for reconstructing much of the life history of an individual, as accentuated increments visible in polarized light microscopy record incidents of physiological stress during the formation of dental tissues. Combined with counts of the normal periodic growth increments, they provide a means of reconstructing the chronology of dental development, age at death, and the ages at which stress occurs. In this study, we determine age at death and reconstruct the chronology of dental development in two male anubis baboons from Uganda and two female baboons from the Awash National Park hybrid zone. For the female baboons, we used the dates of death and rainfall records for the region to determine date of birth, ages at periods of physiological stress, dates at which these stresses occurred, and rainfall amounts for those months. Ages determined histologically for each specimen are comparable to ages estimated from dental emergence schedules and dental scores for wild baboons. Crown formation times are longer than those reported in radiographic studies of captive yellow baboons. Age at initiation of crown formation is similar to that reported for radiographic studies, but ages at completion of crown formation are consistently later. The pattern of stresses is similar in the two female baboons, suggesting that individual life history intersects with local ecology to produce a pattern of accentuated increments occurring during the weaning process and at the onset of menarche, as well as during the first postweaning dry and rainy periods.

A dynamic interaction between aggression and grooming reciprocity among female chacma baboons

We used data from a natural experiment on adult female chacma baboons, Papio cynocephalus ursinus, to test the hypothesis that variation in aggression through time influences patterns of grooming reciprocity within a social group. Owing to a change in the baboons' competitive regime, we were able to compare data from periods when aggression was high (period 1) and low (period 2). During period 2, the slope of the relationship between aggression and rank was significantly shallower than during period 1 and less aggression was directed at the lowest-ranking females suggesting there had been a reduction in the dominance gradient. We attributed this to reduced effectiveness of dominance as a means of excluding other females from feeding resources. The reduction in aggression during period 2 was accompanied by an increase in grooming reciprocity between dyads suggesting that high-ranking females no longer attracted grooming by subordinates in exchange for tolerance, and that grooming in period 2 was exchanged for its intrinsic benefits. The loss of rank-related effects on grooming reciprocity in period 2 compared with period 1 further confirmed this. These findings show that female baboons are able to respond flexibly and swiftly to changes in their social circumstances and that a dynamic approach to primate social interactions is worth pursuing. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Infants as a commodity in a baboon market

We used data from adult female chacma baboons, Papio cynocephalus ursinus, to provide the first test of hypotheses on interchange trading and the structure of a biological market (Noë & Hammerstein 1994, Behavioral Ecology and Sociobiology,35, 1–11) within a primate group. The interchange commodities selected were grooming and handling of infants less than 3 months of age. Patterns of grooming in relation to infant handling showed strong evidence for interchange. Grooming for infant access was initiated by potential handlers and was significantly likely to be nonreciprocated. More critically, the data show that infant ‘supply’ created a market effect: grooming bout duration (the price ‘paid’ for handling) was inversely related to the number of infants present in the group. In addition, there was an inverse relationship between grooming bout duration and the rank distance between mothers and handlers, suggesting that higher-ranking mothers could demand a higher price for infant handling. Where rank distance was high, females were able to handle infants without grooming. Dominance could thus be used to disrupt the infant market effect. If biological markets models are to be fully applicable to primate groups (and those of other social mammals) then the potentially distorting effect of dominance needs to be incorporated into the framework. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Genetic effective size of a wild primate population: influence of current and historical demography.

A comprehensive assessment of the determinants of effective population size (N(e)) requires estimates of variance in lifetime reproductive success and past changes in census numbers. For natural populations, such information can be best obtained by combining longitudinal data on individual life histories and genetic marker-based inferences of demographic history. Independent estimates of the variance effective size (N(ev), obtained from life-history data) and the inbreeding effective size (N((eI), obtained from genetic data) provide a means of disentangling the effects of current and historical demography. The purpose of this study was to assess the demographic determinants of N(e) in one of the most intensively studied natural populations of a vertebrate species: the population of savannah baboons (Papio cynocephalus) in the Amboseli Basin, southern Kenya. We tested the hypotheses that N(eV) < N < N(eI) (where N = population census number) due to a recent demographic bottleneck. N(eV) was estimated using a stochastic demographic model based on detailed life-history data spanning a 28-year period. Using empirical estimates of age-specific rates of survival and fertility for both sexes, individual-based simulations were used to estimate the variance in lifetime reproductive success. The resultant values translated into an N(eV)/N estimate of 0.329 (SD = 0.116, 95% CI = 0.172-0.537). Historical N(eI), was estimated from 14-locus microsatellite genotypes using a coalescent-based simulation model. Estimates of N(eI) were 2.2 to 7.2 times higher than the contemporary census number of the Amboseli baboon population. In addition to the effects of immigration, the disparity between historical N(eI) and contemporary N is likely attributable to the time lag between the recent drop in census numbers and the rate of increase in the average probability of allelic identity-by-descent. Thus, observed levels of genetic diversity may primarily reflect the population's prebottleneck history rather than its current demography.