Serum aminopeptidases in pregnant vervet monkeys (Cercopithecus aethiops)

Two distinctive aminopeptidase isozymes have been identified in the serum of the vervet monkey. The l-methionine-sensitive cytosol aminopeptidase (AP; E.C. 3.4.11.1) is present in all samples, while the cystyl aminopeptidase (CAP; E.C. 3.4.11.3) isozyme, which is resistant to inhibition by 0.1 m l-methionine, is found only in the serum of pregnant females. The pregnancy-specific CAP isozyme appears in the serum between the fifth and the eleventh weeks of a nearly 22-week pregnancy. The overall aminopeptidase activity and the activity of the l-methionine-insensitive isozymes alone are both significantly greater in the serum of pregnant females than in nonpregnant females. Consequently, the presence of the cystyl aminopeptidase isozyme in the serum is a useful diagnostic indicator of pregnancy in the vervet monkey.     

Pregnancy outcome in free-ranging vervet monkeys (Cercopithecus aethiops)

A preliminary assessment of individual female differences in conception rate and fetal wastage has been determined for a population of wild vervet monkeys (Cercopithecus aethiops). One of three troops of vervet monkeys, the subjects of a long-term behavioral study, was trapped and blood was obtained for electrophoretic analysis. Pregnant females exhibited a distinctive serum aminopeptidase phenotype allowing a conclusive determination of pregnancy. Of the seven females diagnosed as pregnant, three later gave birth. Of the females that aborted, two were nulliparous and one was very old. Studies of captive animals have indicated that age and rank may affect a female's ability to carry a fetus to term. These factors, rather than the trapping procedure, may have been responsible for most of the fetal loss in the trapped troop. A comparison of all three troops for a 3-year period indicated that there were fluctuations in yearly birth success of individual females, as well as a relatively high miscarriage rate. The results of this study indicate the advantages of obtaining joint behavioral and biological data.     

Twinning in a colony of vervet monkeys (Cercopithecus aethiops sabaeus)

From 1975 through 1991, three sets of twins were born from a total of 693 live and stillborn births (0.43%) at the UCLA/Sepulveda Veterans Administration Medical Center Nonhuman Primate Research Laboratory, CA. None of the twin's mothers were related. Positive patrilineal relationships have not been established; however, a brother (not a twin) of the first set of twins may have fathered the third set. All twins were born to multiparous females and, in each case, only one infant survived beyond 4 days. One set of twins was dizygotic; the genetic status of the others is unknown. © 1994 Wiley-Liss, Inc.     

Captive propagation of vervet monkeys (Cercopithecus aethiops) in harems

A small breeding colony of captive vervet monkeys (Cercopithecus aethiops), consisting of ten single male harem groups, was established in Kenya. Vervets were extremely prone to stress after capture and manipulative procedures led to high mortalities. Six weeks were required for partial habituation, after which routine handling was not too problematic. However, complete adjustment to captivity took a minimum of one year. Establishment of stable breeding groups from adult animals initially proved difficult because of fighting among females. Once harem groups stabilized, reproductive rate was high with just under 90% pregnancies and 85% livebirths annually. Births exhibited a seasonal pattern similar to that reported from wild populations in Kenya.     

Blood protein variation in a population of ethiopian vervet monkeys (Cercopithecus aethiops aethiops)

Seven small groups of vervet monkeys (Cercopithecus aethiops aethiops), totaling 124 individuals, from Awash National Park, Ethiopia, were trapped and blood samples were obtained. Twenty-three loci were examined by starch gel electrophoresis and four loci, Tf, E, ADA, and PMG2 were found to be polymorphic. The average heterozygosity (H?) of the population was calculated to be 5.6%. No significant deviations from Hardy-Weinberg equilibrium proportions occurred and a chi-square test for group homogeneity was also not significant. Average F_ST for all polymorphic loci was calculated to be 0.062. This suggests that the entire group functions as a single Mendelian population.     

Leptospires in vervet monkeys (Cercopithecus aethiops Sabaeus) on Barbados

Agglutinins to Leptospira were found at titers of greater than or equal to 1:100 in 150 of 501 (29.9%) vervet monkeys (Cercopithecus aethiops sabaeus) bled within 1 mo of capture in Barbados. Including a further 34 of 145 bled within 1 yr of capture, the seropositivity prevalence was 28.5%. A further 35 monkeys (5.4%) had traces of agglutinins or gave titers of 1:50. The proportion of seropositive adults (41.5%) was more than twice that of seropositive immature monkeys (17.6%). Among adults, 49.2% of males and 35.7% of females were seropositive, while among juveniles proportions of seropositive males and females were similar (17.8% and 17.4%, respectively). Seropositivity prevalences tended to increase in proportion to rainfall. In each of 165 of the 184 positive sera, a single serogroup predominated in the serological reactions. These serogroups were Ballum (61%), Icterohaemorrhagiae (16%), Autumnalis (15%), Pyrogenes, Panama, Pomona, Tarassovi and Canicola (8% altogether). In the other 19 positive sera no single serogroup predominated. Serial bleeding showed that vervet monkeys can retain naturally-acquired antibodies to Leptospira for at least 2.5 yr. The evidence suggests that vervet monkeys in Barbados are transmitting leptospiral infections among themselves independently of other groups of animals, and are not a major source of human leptospirosis.     

Female mate choice in vervet monkeys (Cercopithecus aethiops sabaeus)

Female mate choice was examined in a captive group of vervet monkeys (Cercopithecus aethiops sabaeus). Male-female interactions were examined under both dyadic and group conditions to determine whether females mate with different males under the two conditions. Results showed that all females preferred to mate with the alpha male under both dyadic and group conditions. Alpha females, however, were more successful than subordinate females in rejecting the sexual solicitations of subordinate males. Thus female dominance status played an important role in determining the degree to which females exercised mate choice.     

Social roles in captive vervet monkeys (Cercopithecus aethiops sabaeus)

Behavior clusters were identified through factor analysis of individual behavior profiles over time and across groups of different composition in a captive vervet monkey (Cercopithecus aethiops sabaeus) colony. The six resulting factors were assessed through examination of (1) the behaviors contributing to each factor, (2) the properties of the factors across groups, and (3) the distribution of individuals along the factor dimensions. Three of the clusters were judged to represent the social roles of Control Male, Control Female, and Subordinate and the other three described the behaviors associated with the developmental stages of yearling (Playful—Protected), juvenile female (Infant focus) and juvenile male (Sex-Play).     

Social and solitary play in a colony of vervet monkeys (Cercopithecus aethiops)

This study describes and defines play in a laboratory colony of vervet monkeys (Cercopithecus aethiops). Play is divided into 26 units of behavior and the frequencies of these behaviors are recorded. Analysis shows that sex, age, and dominance have effects on some play behaviors. The play behavior of each age/sex group within the colony is described both quantitatively and qualitatively. Adult females are characterized by reinforcement of the play of immature monkeys, adult males by rough play with older male juveniles, four-year-old females and three-year-old males by stimulation of play in young infants, and males in general by a preference to play within their peer group. It is suggested that modified repetition of behaviors, diversified interactions, and innovative behaviors, are important qualities of play, and are essential to the adaptive plasticity of behavior in primates.     

Selection of secondary growth areas by vervet monkeys (Cercopithecus aethiops)

Habitat selection by a group of vervet monkeys (Cercopithecus aethiops) living on the savanna peninsula of St. Kitts was investigated by the intensive sampling of 12 transects. The vervets exhibited nonrandom use of habitats. Examination of 20 ecological variables in each of the habitat types revealed that the vervets preferentially used areas of secondary growth characterized by high density and diversity of tall food plants. It is suggested that the preferential use of secondary growth habitat can be attributed to the fact that these areas have high levels of plant productivity and that they have a large proportion of their productivity available for consumption.     

The development of hepatic granulomas in 20 Krad irradiated Schistosoma mansoni cercaria vaccinated grivet monkeys (Cercopithecus aethiops aethiops)

The absence of appropriate animal models is a challenge for those designing anti-schistosome vaccines. In order to observe the development of hepatic granulomata, 20 Krad irradiated cercaria vaccinated grivet monkeys (Cercopithecus aethiops aethiops) were experimentally infected with Schistosoma mansoni. Most human clinical manifestations of schistosomiasis were noted in the infected monkeys. Intraperitonial immunization with 20 Krad irradiated cercaria resulted in a relatively less granulomatous reaction and lower egg mass (P<0.05) than in the controls. The mean total adult worms and egg production was also lower in the vaccinated group. This study underlines the significant role of irradiated cercariae vaccination on the establishment of female adults and consequent reduction of pathology in the grivet Cercopithecus aethiops aethiops.     

Group fusions and minimum group sizes in vervet monkeys (Cercopithecus aethiops)

Six unequivocal cases of group fusion occurred between 1984 and 1988 in a declining population of vervet monkeys (Cercopithecus aethiops) in Amboseli National Park, Kenya. In each case, the remaining group members abandoned their territory and joined a neighboring group shortly after the group lost its penultimate adult. Because the number of juveniles did not appear to influence the timing of fusion, only adults (both males and females) appear able to maintain vervet groups as cohesive units. After examining the relative contributions of adults and juveniles to groupliving, we infer that intergroup competition may be more important than predation avoidance in determining the timing of fusions.     

Longitudinal stability in adult status hierarchies among vervet monkeys (Cercopithecus aethiops)

Status hierarchies were examined in a captive group over a 12-year period (1968–1979) to establish the stability and structure of vervet monkey dominance relationships. Dyadic records of spontaneous avoid, bite, chase, and supplant behaviors are summarized into a win/lose matrix to produce a rank order of status at the end of each calendar year. The 13,717 agonistic acts tabulated are drawn from both focal and ad lib data. Relative rank is computed by dividing the rank position of each individual by the number of individuals ranked for that year. Relative rank was found to be quite stable for adults of both sexes, although males were more variable than females. There was a strong matinrline effect on all captive born animals' rank position. No gender difference in rank was demonstrable. Infants were very subordinate at the end of their first year, but rose to positions near those of their mothers by the end of the fourth year. Presence or absence of canine teeth had no demonstrable effect on status. The results emphasize the relative importance of social learning in the establishment and maintenance of dominance relationships. The apparent gender difference in rank among wild living vervets is hypothesized to be a consequence of the male intergroup mobility. If a male is restrained from emigration, he is strongly affected by his mother's rank as he establishes his own dominance position in the troop.     

Steroid hormone influences on the mating behavior of vervet monkeys (Cercopithecus aethiops)

Eight ovariectomized female vervet monkeys (Cercopithecus aethiops) were tested in heterosexual and isosexual pairs, under estradiol and testosterone treatments. Pairs were tested under two different experimental situations in which the male was either restrained or left free. There were only small behavioral changes across the treatments, involving mainly male responses. Erection time, frequency of intromission, ejaculation, and olfactory investigation increased during estradiol treatment whereas during administration of testosterone erection time, the number of approaches, contacts, and olfactory investigations decreased. Female behaviors were relatively independent of hormone treatment showing only the disappearance of negative responses with estradiol and an increase of yawns with testosterone. Female behaviors were performed at a higher level with male partners than with other females, and the frequencies of spontaneous presents varied with the sex of partner. It is suggested that in vervet monkeys both estradiol and testosterone affect female attractivity, estradiol further influences receptivity, whereas proceptivity appears to be less directly involved in sexual interactions and more related to social context.