Sexual behavior and reproduction ofCercocebus albigena johnstonii in Kibale forest,Western Uganda

Gray-cheeked mangabeys live in multimale social groups. Two groups of these monkeys were studied extensively over a period of 22 months, and a further eight groups were observed opportunistically. Data on the occurrence of sexual swelling infernales were collected and the different phases of swelling and deflation are described in detail together with data on their duration. The data were found to agree broadly with those presented by other workers on captive animals. Pre and postpartum swellings are described. The majority of copulations was observed to occur at peak swelling and a specific gesture, the head flag, was noted as a solicitation. The data on initiation of copulations show that the males initiated more copulations than the females. However, female-initiated copulations ended in ejaculation more often than male-initiated copulations. The behaviors of the mangabeys during precopulation and copulation were found to be broadly similar to those of the macaque. Copulations were observed most often on the day of peak swelling;however, adult males were the only animals to copulate prior to peak swelling. Subadult male copulations were most often after peak swelling. Masturbation was observed to ejaculation on two occasions. The data show gestation periods of between 184 and 189 days. A mean interbirth interval was calculated to be 33.33 ± 15.87 months.     

Patterns of male residency and intergroup transfer in gray-cheeked mangabeys (Lophocebus albigena)

We describe the movements and fates of 36 collared gray-cheeked male mangabeys (Lophocebus albigena) that resided in seven social groups in Kibale National Park, Uganda. The male mangabeys were captured, radiotagged, and then contacted regularly over a period of up to 8 years. Individuals varied considerably in how tightly they were associated with their groups. "Central" males were usually found in close spatial association with their own groups, but they sometimes visited others. "Peripheral" males were often found several hundred meters away from their own groups. Most adult males were characterized by repeated intergroup transfers, manifested as "visits" and "dispersals." Visits were transfers that did not result in mating. The visits were brief, and ranged from a few minutes to a few days before the male returned to his previous group, moved on to another group, or returned to solitary life. The term "dispersal" refers to a transfer that results in mating, after which the male remains in the new group. Young males began to drift away from their natal groups in early subadulthood, but the timing of first associations with estrous females in other groups was highly variable. Natal dispersers were generally solitary for a month or more, and at least half moved into nonadjacent groups. Secondary dispersal was common. After they immigrated, adult males remained in a group for a median of 19 months before they emigrated again, with the probability of departure being approximately constant in time. Secondary dispersal was usually made into an adjacent group and lasted less than 7 days. Emigration and immigration were not seasonal, and males emigrated singly and apparently independently; however, immigrations were clumped in time, and male dispersal contributed to considerable heterogeneity of group composition. L. albigena dispersal patterns are intermediate between those described for Papio baboons and forest Cercopithecus, and models that predict demographic consequences of dispersal for baboons can be refined to apply to mangabeys.     

Information content of sexual swellings and fecal steroids in sooty mangabeys (Cercocebus torquatus atys)

The accuracy and precision of sexual swellings and fecal steroids as measures of ovarian function and the periovulatory period were compared in 4 sexually mature, individually housed, sooty mangabey females. Fecal samples were collected daily over a 10-week period during the normal breeding season. Serum was collected 3×/week, daily during peak swelling, and sex skin was rated 5×/week on a 0–5 relative scale. Both fecal estradiol (fE₂) and progesterone (fP₄) were significantly correlated with serum values in composite E₂-aligned profiles and within the cycles of individual females with average correlations of r_s = 0.6. Follicular phase means for fE₂ and luteal phase means for fP₄ were significantly correlated with the serum means across cycles, suggesting that fecal concentrations could be used to accurately evaluate cycle phases within and across females. In contrast, the timing of peak swelling relative to the periovulatory period varied considerably across the cycles of individual females. Although maximum tumescence appears to bracket the periovulatory period, individual differences in the duration of peak swelling and the timing of its onset and end tend to obscure the exact time of ovulation in relation to maximal tumescence. These data illustrate the utility of fecal steroid analysis as a tool for further evaluation of the signal value of sexual skin and its role in mating interactions. © 1996 Wiley-Liss, Inc.     

Life history of captive gray-cheeked mangabeys: Physical and sexual development

Ontogeny refers to every aspect of the development of an individual. In this respect growth and sexual maturation are useful life-history parameters that can be correlated with developmental features of social behavior. In this paper, I analyze body-weight growth and sexual maturation in captive gray-cheeked mangabeys (Cercocebus albigena). I also describe the development of external morphological characteristics, used as “physical markers.” Body-weight growth is analyzed in 15 males and 7 females. Individual weight velocity curves for animals of both sexes showed an, early peak around 2 years of age. Males had a later growth spurt, peaking between 4 and 6 years of age. Females showed no clear second growth acceleration (spurt), but they experienced an interruption of their weight growth deceleration between 3 and 5 years of age, which is generally coincident with puberty. In females there is a close relationship between weight and the occurrence of the first swelling of their sexual skin. These developmental parameters are compared to those described in baboons and macaques.     

Studies of CD40L expression by lymphoid cells from experimentally and naturally SIV-infected nonhuman primate species.

Dysfunction of T lymphocytes is well documented in HIV-1-infected individuals; however, the mechanisms responsible for the noted dysfunction are not well understood. CD40L is an important costimulatory molecule that helps initiate immune responses, and there is controversy regarding whether or not expression of CD40L is compromised in HIV-1-infected individuals. We have utilized the SIV infection of experimentally infected (disease-susceptible) and naturally infected (disease-resistant) nonhuman primates as animal models of human AIDS to address this issue. Little is known concerning the expression of CD40L in nonhuman primates. Studies were conducted to determine the frequency, density, phenotype, and kinetics of CD40L expression by in vitro activated peripheral blood mononuclear cells (PBMCs) from different species of uninfected and SIV-infected monkeys. Data obtained show marked differences in the density and phenotypic lineage that expresses CD40L in lymphoid cells from the three species examined. However, no detectable differences were noted in the frequency and density of CD40L expression by in vitro activated lymphoid cells from uninfected and SIV-infected disease-susceptible rhesus macaques and seropositive as compared to seronegative disease-resistant sooty mangabeys. These data suggest that phenotypic expression of CD40L is not compromised due to SIV infection.     

Hormonal correlates of ontogeny in baboons (Papio hamadryas anubis) and mangabeys (Cercocebus atys)

This study investigates the relationship between serum hormone levels and morphometrics during ontogeny in olive baboons (Papio hamadryas anubis) and sooty mangabeys (Cercocebus atys), to test hypotheses about the endocrine regulation of species size differences. First, we expect that levels of hormones and binding proteins predict size change during ontogeny in both species. Second, a high level of integration among the hormones and binding proteins analyzed is expected, with the implication that they act in combination to influence the development of body size and shape. Utilizing a mixed longitudinal sample, we compare change in 18 different measurements, which reflect overall size growth as well as growth in length and circumference, with levels of six growth-related hormones and binding proteins. We examine the relationship between hormone and binding protein levels and morphometrics, using multivariate analyses and "arithmetically-estimated" velocity curves of hormones, binding proteins, to characterize how the endocrine factors analyzed relate to growth. Results suggest that levels of these endocrine factors can be used to predict local and overall growth during ontogeny and that integration between multiple hormone axes is indicated. While important for growth in both species, ontogenetic changes in hormone and binding protein levels are more tightly correlated with changes in morphometric measurements in baboons than mangabeys. These results have important implications for understanding why some smaller-bodied species have higher absolute growth-related hormone levels than larger-bodied species.     

Competition, predation, and the evolutionary significance of the cercopithecine cheek pouch: the case of Cercopithecus and Lophocebus

Reports of cercopithecine cheek pouch use and functional significance are largely anecdotal, and to date there have been no investigations into its use by species living in closed forest habitats. Here, I report on cheek pouch use in Cercopithecus ascanius and Lophocebus albigena in the Kibale National Park, Uganda, between July-October 1997. Two hypotheses were evaluated: this feature was selected for because of its role in 1) increasing feeding efficiency via a reduction in potential feeding competition, and/or 2) reducing vulnerability to predation. Results indicate that both species were more likely to use their cheek pouches when feeding on contestable foods and, after filling cheek pouches, retreated to more densely vegetated ("safer") positions for processing food. There was no influence of age and sex on L. albigena cheek pouch use. Subadult C. ascanius cheek-pouched less frequently than adults, although there were no differences between adult males and females. There was no relationship between feeding-patch size and number of plant food items cheek-pouched in either species. However, the diameter of breast height (dbh; a measure of patch size) of trees in which C. ascanius used their cheek pouches was significantly larger than the dbh of trees in which they did not. Both species were more likely to use their cheek pouches in the presence of greater numbers of conspecifics. These data provide insight into the relationship(s) among oral anatomy and feeding efficiency, and facilitate understanding into the selection for this important oral feature in stem cercopithecines.     

Sex differences in behavior of endangered mangabeys (Cercocebus galeritus chrysogaster)

Six adult golden-bellied mangabeys (Cercocebus galeritus chrysogaster) displayed sex differences in aggression, grooming, and vocalization. These sex differences persisted across different current living conditions, time in captivity, rearing conditions, presence of offspring, and active mating conditions. The sex differences are evidently quite robust.     

Female grooming markets in a population of gray-cheeked mangabeys (Lophocebus albigena)

Primate female allogrooming models based on biological marketstheory predict that grooming is "time matched" within bouts,that is, the amount of time the first female grooms predictsthe amount of time the second one grooms. The models also predictthat when female–female contest competition is weak, groomingis traded for grooming, but when female–female contestcompetition is strong, grooming may be traded for other commoditiessuch as feeding tolerance, and grooming discrepancy betweenmembers of dyads is rank related. We tested these predictionsusing data collected from adult and subadult female gray-cheekedmangabeys (Lophocebus albigena) (N = 26) in 5 groups in KibaleNational Park, Uganda. We found that, overall, females reciprocatedin 33% of grooming bouts. Among reciprocated bouts, femalesin all 5 groups showed time matching. In 2 groups, we also foundrank-related grooming discrepancies but showing opposite patternsto each other. Consistent with predictions based on biologicalmarkets theory, these groups may have been under greater feedingcompetition, revealed more by adjustments in ranging behaviorthan increased agonistic rates. Although these results supportcurrent allogrooming models, they also suggest that the modelsmay become more robust if the influence of scramble competitionis incorporated. In addition, they emphasize the flexibilityand dynamic nature of female competitive relationships withinthe same population of primates.     

Sooty mangabeys and rhesus macaques exhibit significant divergent natural killer cell responses during both acute and chronic phases of SIV infection

A correlation between NK cells and rate of disease progression in HIV-1-infected individuals has been documented. The role NK cells play in disease outcome can optimally be studied in SIV-infected disease susceptible rhesus macaques (RM) and SIV-infected disease resistant sooty mangabeys (SM). In this study, three main subsets of CD16⁺CD56⁻, CD16^−/dimCD56⁺ and CD16⁻CD56⁻ NK cells have been identified with the predominant CD16⁺CD56⁻ subset being primarily responsible for cytolytic activity in both species. Cross-sectional studies revealed a significant decline in the frequency and function of this cytolytic subset in SIV-infected RM while an increase occurred in SIV-infected SM. Longitudinal studies revealed that an earlier NK response during acute infection occurred in all SIV-infected SM and in select SIV-infected RM that eventually controlled viral load set point during chronic infection, suggesting that early NK activity and continued maintenance of this cell lineage may indirectly contribute to disease resistance.