Intraspecific chromosome variation in Cebus apella (cebidae,platyrrhini): The chromosomes of the yellow breasted capuchin Cebus apella xanthosternos wied, 1820

Chromosome studies in six wild-caught specimens of Cebus apella xanthosternos showed a distinctive chromosome pair number 11 that made it possible to distinguish this subspecies from other Cebus apella. The characteristic chromosome pair had intercalar heterochromatin unlike the “standard” chromosome type of Cebus apella and other species of the same genus, in which this chromosome pair shows a large, terminal, heterochromatic block. A comparison at the chromosomal level between different Cebus apella populations suggests that chromosome 11 in Cebus apella xanthosternos is a derived chromosome that has probably become fixed in this subspecies, either by selection or by drift in a small isolated population.     

Chromosome comparison among five species of platyrrhini (Alouatta caraya,Aotus azarae,Callithrix jacchus,Cebus apella,andSaimiri sciureus)

Karyotypes of 82 individuals from five Platyrrhini species (Alouatta caraya, Aotus azarae, Callithrix jacchus, Cebus apella, andSaimiri sciureus) were studied and compared using a G-banding technique. Cytogenetic analysis showed full chromosome or full arm homologies among these geographically neighbouring species. A small number of chromosomal rearrangements (inversions, deletions, and translocations) could be detected among these taxa. These five species are closely related in chromosomal evolution. An interesting correspondance was found betweenCebus apella chromosomes and those of the other four species.Alouatta caraya andCebus apella are the closest species.Callithrix jacchus andAotus azarae would have the most separated karyotypes.     

Constitutive heterochromatin polymorphism in Lagothrix lagothricha cana,Cebus apella,and Cebus capucinus

We describe the C-bands in the karyotypes of Lagothrix lagothricha cana, Cebus apella and Cebus capucinus. The C-banding patterns show both a high degree of polymorphism as well as the presence of terminal and interstitial C-bands. Varying amounts of heterochromatin result in dimorphism of some chromosome pairs. The high incidence of chromosome rearrangements found in the Cebidae may be due to the presence of terminal and interstitial C-bands.     

Response Toward Novel Foods and Novel Objects in Wild Cebus apella

Animals respond to novel stimuli via explorative or neophobic behavior or both. The coexistence of these responses toward novel foods may be a successful adaptive strategy for a generalist species such as Cebus apella, because it allows the gradual introduction of new foods into the diet and reduces the risk of poisoning by ingestion of large amounts of toxic compounds (Glander, 1982; Milton, 1993; Visalberghi, 1994). Neophobia has been studied mostly in captivity. We investigated responsiveness to novelty in a group of 25–30 wild tufted capuchins (Cebus apella) in Iguazü National Park (Argentina). They had been habituated to visiting sites where bananas were provided on three elevated platforms. We presented novel stimuli on an adjacent platform. There were 4 experimental conditions with 10 sessions each: the Novel Food condition, the Novel Object condition, the Control condition, in which the platform was empty, and the Banana condition. In the Novel Food and Novel Object conditions, a new stimulus—food or object—was on the platform during each session. The Banana condition provided information on capuchin response to a familiar preferred food. Overall, capuchins were less responsive toward novel objects than toward novel foods; however, although cautious, they ate small amounts of the novel foods. Age affected individual responsiveness toward novel foods, whereas sex affected responsiveness toward novel objects. Capuchins ignored the empty platform. Our findings are in agreement with the idea that tufted capuchins can adapt to new habitats by gradually exploiting new food sources.     

Pattern of late DNA replication of the allocyclic X chromosome in Cebus apella and Leontopithecus rosalia chrysomelas fibroblasts

The pattern of late DNA replication in the allocyclic X chromosome has been studied in the primary fibroblasts of two neotropical primates (Cebus apella and Leontopithecus rosalia chrysomelas). A comparison with previous reports showed a pattern identical with that of (1) the allocyclic X chromosome of human fibroblasts, and (2) the allocyclic X chromosome of rhesus and Cebus lymphocytes. Our results show that at least in one species (C. apella), and probably in rhesus and Leontopithecus, there is no tissue-specific difference between the late DNA replication patterns of the allocyclic X chromosome as there is between human lymphocytes and fibroblasts.     

Contiguous distribution of two species of Cebus monkeys in El Tuparro National Park,Colombia

The geographic distribution of two congeneric monkeys (Cebus albifrons and C. apella) was studied in El Tuparro National Park in the llanos of eastern Colombia. Extensive trips were undertaken by land and river to collect 268 precisely located groups of these two species. The distributions of these monkeys were generally mutually exclusive and parapatric, contrasting with their known sympatry in closed-canopy rainforest farther to the south. The replacement of one species by the other was abrupt along the northern water courses in the park; however, the two species' ranges partially overlapped and contained islands of sympatry towards the southern parts of the park, where forests are more extensive. Along the rivers, C. albifrons was found in seasonally inundated forests and woodlands that were seldom entered by C. apella. Such inundatable vegetation was extensive in downriver sites in the typically flat llanos geography of this part of Colombia. Although some differential use of habitat was demonstrated, many forests containing the two species seemed essentially identical so that historical precedence, competition, or both may also be posited to partially explain the distributions, although this remains to be demonstrated.     

Canine Dimorphism and Interspecific Canine Form in Cebus

I investigated canine dimorphism and interspecific canine form in adult specimens from 4 capuchin species (Cebus albifrons, C. apella, C. capucinus, and C. olivaceus). I used various univariate and multivariate statistics, which are based on 6 variables, to test several hypotheses that are based upon the finding that canine dimorphism is strongly associated with intermale competition in platyrrhines (Kay et al., 1988), Greenfield (1992a), Plavcan and van Schaik (1992, 1994). Results from the indices of canine dimorphism and the unpaired t-tests corroborate the prediction that males of each species possess significantly larger canines than those of females. Large male canines are especially prominent in 2 variables, maxillary and mandibular canine height. Greene's t-test (1989) does not support the prediction that Cebus apella and C. olivaceus possess a larger degree of canine dimorphism relative to C. albifrons and C. capucinus. No interspecific differences in degree of canine dimorphism are indicated by this test. Results of the discriminant function analyses (DFA) do not find that Cebus apella and C. olivaceus possess different canine form relative to C. albifrons and C. capucinus as predicted. However, Cebus apella is differentiated from the untufted capuchins (C. albifrons, C. capucinus, and C. olivaceus) by the DFA. I suggest that intermale competition is the primary selective force underlying the observed morphological patterns; however, it does not explain all the variation associated with canine dimorphism in Cebus.     

Interspecific Interactions Between Cebus capucinus and Other Species: Data from Three Costa Rican Sites

Capuchins exhibit considerable cross-site variation in domains such as foraging strategy, vocal communication and social interaction. We report interactions between white-faced capuchins (Cebus capucinus) and other species. We present comparative data for 11 groups from 3 sites in Costa Rica that are ecologically similar and geographically close, thus reducing the likelihood that differences are due solely to genetic or ecological differences. Our aim is to document both the range of variation and common elements across sites and situations. We also consider factors that contribute to the variation or consistency or both, including social learning, local ecology, and temperament. We consider 4 categories of allospecifics: (1) vertebrate prey, (2) potential predators, (3) feeding competitors, and (4) neutral species. Although we cannot rule out local differences in ecology, our data suggest that social learning may account for at least some cross-site differences in behavior toward allospecifics. Our strongest finding is that boldness, aggression and pugnacity are displayed consistently across sites, groups and circumstances, even in interactions with neutral species, which reflects a critical aspect of species-specific temperament in Cebus capucinus that has been evolutionarily developed and reinforced through highly opportunistic foraging, strong predator defense, and active hunting. We suggest directions for future research, particularly in regard to primate temperament as an evolved trait with consequences for fitness.     

Locomotor and postural behavior in Alouatta palliata and Cebus capucinus

Positional behavior of two platyrrhine monkeys, Alouatta palliata and Cebus capucinus, was observed at La Pacifica and Santa Rosa National Park, Costa Rica. Frequency data for locomotion, postures, support diameters, orientation of supports, and use of canopy were recorded on focal males and females. Alouatta palliata is a frequent user of arboreal quadrupedalism (47%) and climbing (37%), with bridging (10%) representing the next most frequent type of locomotion. Intraspecific comparisons show the smaller-sized females of Alouatta to prefer very small diameter supports, the lower canopy, and to climb more frequently than the larger males—a pattern opposite to that which has been documented to occur with increasing body size across species. A more limited study on Cebus capucinus shows this species to be highly quadrupedal (54%) with moderately high locomotor frequencies for climbing (26%) and leaping (15%).     

A Potential Distribution Model and Conservation Plan for the Critically Endangered Ecuadorian Capuchin, Cebus albifrons aequatorialis

Conservation actions that effectively and efficiently target single, highly threatened species require current data on the species’ geographic distribution and environmental associations. The Ecuadorian capuchin (Cebus albifrons aequatorialis) is a critically endangered primate found only in the fragmented forests of western Ecuador and northern Peru, which are among the world’s most severely threatened ecosystems. We use the MAXENT species distribution modeling method to model the potential distribution and environmental associations of Cebus albifrons aequatorialis, using all known presence localities recorded within the last 2 decades as well as 13 climate, topography, vegetation, and land-use data sets covering the entire geographic range of the subspecies. The environmental conditions that our model predicted to be ideal for supporting Cebus albifrons aequatorialis included ≥20% tree cover, mild temperature seasonality, annual precipitation <2000 mm, and low human population density. Our model identified 5028 km² of suitable habitat remaining, although many of these forest fragments are unprotected and are unlikely to support extant populations. Using the median population density across all sites for which data are available, we estimate the total carrying capacity of the remaining habitat to be 12,500 total individuals. The true number of remaining individuals is likely to be considerably lower due to anthropogenic factors. We highlight four critical regions of high predicted suitability in western Ecuador and northern Peru on which immediate conservation actions should focus, and we lay out clear priorities to guide conservation actions for ensuring the long-term survival of this gravely threatened and little known primate.     

Cebus nigritus impact the seedling assemblage below their main sleeping sites

Capuchin monkeys (Cebus nigritus) in Argentina prefer particular sleeping trees they maintain over the years. We compared species composition and abundance of seedlings under these sites with that of control sites. Species richness and abundance of seedlings was higher under sleeping trees than in control plots. Moreover, the proportion of dispersed versus non-dispersed species and individuals by capuchins was higher under the most frequently used sleeping trees than in control plots located in other areas of their home range. Thus, the dominance of plant species dispersed by these primates in the seedling assemblages below sleeping trees confirm the strong weight of C. nigritus and their potential influence in the dynamics of the seedling populations in the forest.

Los monos capuchinos (Cebus nigritus) en Argentina prefieren árboles dormideros particulares que mantienen durante varios años. Comparamos la composición y la abundancia de especies de plántulas debajo de estos sitios con la de sitios controles. La riqueza y abundancia de especies de plántulas fue mayor debajo de árboles dormideros que en parcelas controles. Además la proporción de especies e individuos dispersados vs. no dispersados por los capuchinos fue mayor debajo de los árboles dormideros más frecuentemente usados que en parcelas controles ubicadas en otras partes de su área de acción. Así la dominancia de las especies de plantas dispersadas por estos primates en los ensambles de plántulas debajo de los árboles dormideros confirma el fuerte peso de C. nigritus y su influencia potencial en las dinámicas de las poblaciones de plántulas en el bosque.     

Vertebrate Predation and Food-Sharing in Cebus and Pan

Capuchins and chimpanzees are the only nonhuman primates apart from baboons known to prey systematically upon relatively large vertebrates. Vertebrate predation is common and well documented in Pan troglodytes, rare in Pan paniscus, and commonly reported but infrequently studied in Cebus. Food-sharing is common in both Pan species but rarely reported for wild capuchins. I present data on vertebrate predation and food-sharing by white-faced capuchins (Cebus capucinus) from ongoing field studies at Santa Rosa National Park, Costa Rica. We have observed 106 successful predation events resulting in the capture of 156 prey items during 2929 observation hr (5.35 prey per 100 hr). Squirrels and nestling coatis comprised half of the prey taken; the remainder were mainly nestling birds and eggs. Adult males took 52% of all prey and 67% of squirrels. Squirrels are actively hunted and about 65% of them are adults. I estimated that the average capuchin group kills 43–50 squirrels annually, mostly during the dry season. Capuchins hunt squirrels in groups 81% of the time, and 17% of hunts are successful. There is no evidence for cooperative hunting, but occasional collaboration is suggested. Rates of food-sharing were low (1.7 per 100 hr), and meat was the only food shared between adults. I compare predation and food-sharing in C. capucinus with published data for Pan troglodytes, primarily in Gombe and Taï National Parks. I discuss sex differences, hunting strategies, the relationship between hunting and food-sharing, and various ecological and social factors that may promote vertebrate predation in Pan and Cebus.     

Chromosome studies of Cebus apella: The standard karyotype of Cebus apella paraguayanus,Fischer, 1829

Chromosome studies were performed on 40 specimens identified as Cebus apella paraguayanus, Fischer, 1829, which had been wild-caught in Santa Catalina (Republic of Paraguay). Elongated chromosome spreads obtained from lymphocyte cultures were sequentially stained with different techniques, and a constant pattern of 382 bands was identified in all specimens. A standard karyotype based on the measurements of the total chromosome length and the G-Q banding pattern is proposed.     

True anting by the capuchin,Cebus capucinus

I observed capuchins (Cebus capucinus) putting ants (Camponotus sericeiventris) in their fur at Corcovado National Park, Costa Rica. The behavior was similar to “anting” in passerine birds. The literature on anting in birds is reviewed and compared with the relevant references on self-annointment behavior in mammals.     

Manipulative Tendencies of Captive Cebus albifrons

We conducted two experiments to examine the manipulative tendencies of captive Cebus albifrons. In Experiment 1 we examined hand preference for reaching by providing subjects with food either on the cage floor (to facilitate quadrupedal reaching) or at the height of an upright subject's shoulder (to facilitate bipedal reaching). In Experiment 2 we examined combinatorial manipulation by providing subjects with nesting containers and other portable manipulanda. Results indicate that C. albifrons exhibits greater use of the right hand for bipedal versus quadrupedal reaching (exhibiting a group-level lack of bias for bipedal reaching and a left-hand bias for quadrupedal reaching), combines objects using a simple pairing strategy, and uses and produces simple tools. Aspects of these findings parallel those for Cebus apella.     

Carrying, Sharing, and Hand Preference in Tufted Capuchins (Cebus apella)

We examined the relationship among carrying, food-sharing, and hand preference in tufted capuchins (Cebus apella). The rationale was to evaluate further the use of Cebus as an alternative primate model to Pan for behavior relevant to early hominid evolution. We first examined bipedalism and food-sharing within an established social group, and then examined the direction and strength of hand preference for food carrying in an expanded sample. Several aspects of capuchin behavior warrant discussion. First, bipedal carrying and food-sharing occurred more frequently when we provided bulky foods than when we provided smaller foods. Second, food-sharing was characterized by passive tolerance, rather than active giving, between subjects. Third, subjects shared food primarily with immatures and followed a pattern of reciprocal exchange. Finally, we found no evidence for population-level hand preference for carrying. We posit that an array of behavioral similarities among Cebus, Pan, and Homo evolved through convergent processes, and in this regard capuchins can be seen as an alternative primate model to chimpanzees for the evolution of early hominid behavior.     

Viral integration,fragile sites,and proto-oncogenes in human neoplasia

Summary To evaluate the trend of viral integration in the human genome, chromosomal localization of five DNA-containing viruses compiled from literature data was compared to the location of fragile sites and protooncogenes. A total of 35 regionally mapped viral integration sites from tumors and transformed cells were distributed over 19 chromosomes. Of the 35 integration sites 23 (66%) were at the bands of fragile sites, and 7 were one band away (20%). This statistically defines the correlation as highly significant (P = 0.0000183, Fisher's F-test). Five integration sites did not correspond to the location of a fragile site. Thirteen integration sites and proto-oncogenes mapped at the same bands (37%), 6. (17%) were one band apart, and at 16 integration sites (46%) no proto-oncogenes were localized (P = 0.00491). Eighteen viral integration sites, fragile sites, and protooncogenes (51%) were localized at the same bands or one band distant. This clustering of viral integration sites, fragile sites, and proto-oncogenes is statistically highly significant (P = 0.0000118), and indicates nonrandom viral integration in the human genome.     

Postnatal growth allometry of the extremities in Cebus albifrons and Cebus apella: A longitudinal and comparative study

Cebus albifrons and Cebus apella, partially sympatric capuchin monkeys from South America, are known to differ substantially in adult body mass and bodily proportions. C. apella possesses a robust, stocky build in contrast to the more gracile, relatively longer limbed body design of C. albifrons. Average birth weights and adult body lengths of these two congeners, however, are remarkably similar and do not serve to distinguish them. This study examines longitudinal growth rates and patterns of ontogenetic scaling in the extremities (humerus, radius, hand, femur, tibia, foot) in order to document the nature and magnitude of skeletal changes associated with increasing age and body mass. Our data indicate that the growth rates of the six skeletal components of the limbs differ only slightly and somewhat inconsistently between the two species. Body mass, however, increases at a consistently faster rate in C. apella. Relative to body mass, therefore, the extremities of C. albifrons scale much faster than those of C. apella. This implies that at any given postnatal body mass, C. albifrons is longer limbed than C. apella. Conversely, C. apella is heavier than C. albifrons at any given limb length or age. We suggest that such differences in body mass distribution are causally related to differences in locomotor behavior and foraging strategies. Specifically, the relatively long-limbed C. albifrons is probably more cursorial and tends to travel longer distances each day than C. apella. C. apella is a much more deliberate quadruped and is also characterized by especially vigorous and powerful foraging and feeding behaviors. We also compare our results to other (mostly cross-sectional) studies of skeletal growth allometry in nonhuman primates.     

Social behavior of the wild black-capped Capuchin (Cebus apella)

The author undertook a field survey of the capuchin (Cebus apella) lasting 60 days from December 1976 to January 1977, and determined the basic daily activity of its groups and spacing of group members in the day time. Furthermore, based on studies of various types of interactions between individuals of the groups, he was able to show that (1) decisive rank orders exist both among adults and among sub-adults of both sexes; (2) grooming at the resting time is peculiar to adult males; (3) with quite mild agonistic interactions being maintained, a high tolerance exists between the group members; (4) alpha males represent individuals which can be called leaders of groups; and (5) a strong psychological or spiritual bond exists among the adult males, which can be termed a “male-bond.” Furthermore, according to comparative studies on some adjoining groups, it was found that the group structure is strongly influenced by the individuality or character of the adult males of each group. The present findings are generally in agreement with those forC. apella studied by the author and other researchers in other localities. It can be safely said therefore that these findings are probably common to this species of monkey. Based on a comparison with findings for three other species ofCebus, the author attempts to clarify the points of difference betweenC. apella and these three other species ofCebus from the viewpoint of behavioral science and sociology.