Molecular phylogeny and systematics of bald uakaris, genus Cacajao Lesson, 1840 (Primates: Pitheciidae), with the description of a new species

Bald uakaris, genus Cacajao, are Amazonian primates currently classified as one species and four subspecies based on the patterns of pelage coloration. In this study, we test if their current taxonomy is represented by the phylogenetic relationship of the main lineages retrieved from molecular data. We included, for the first time, all bald uakari taxa in a mitochondrial (cytochrome b) and genome-wide (ddRAD) phylogenetic analyses. We also examined the pattern of pelage colouration in specimens from zoological collections. Having determined the number of lineages using Maximum Likelihood and the species tree using coalescent analyses, we test their divergence time using a Bayesian approach. While the cytochrome b analysis only recovered two clades, the ddRAD analysis supported the reciprocal monophyly of five lineages of bald uakaris, with all clades including only individuals with distinct and exclusive diagnostic phenotypic characters. We found that species diversification in Cacajao occurred during the last 300 Kya and may have been influenced by the formation of rivers and flooded forests in western Amazonia. We propose that the four bald uakari subspecies currently recognised can be upgraded to species level and we describe the white uakaris from the basin of the Rio Tarauacá as a new species.

An integrative analysis uncovers a new, pseudo-cryptic species of Amazonian marmoset (Primates: Callitrichidae: Mico) from the arc of deforestation

Amazonia has the richest primate fauna in the world. Nonetheless, the diversity and distribution of Amazonian primates remain little known and the scarcity of baseline data challenges their conservation. These challenges are especially acute in the Amazonian arc of deforestation, the 2500 km long southern edge of the Amazonian biome that is rapidly being deforested and converted to agricultural and pastoral landscapes. Amazonian marmosets of the genus Mico are little known endemics of this region and therefore a priority for research and conservation efforts. However, even nascent conservation efforts are hampered by taxonomic uncertainties in this group, such as the existence of a potentially new species from the Juruena-Teles Pires interfluve hidden within the M. emiliae epithet. Here we test if these marmosets belong to a distinct species using new morphological, phylogenomic, and geographic distribution data analysed within an integrative taxonomic framework. We discovered a new, pseudo-cryptic Mico species hidden within the epithet M. emiliae, here described and named after Horacio Schneider, the pioneer of molecular phylogenetics of Neotropical primates. We also clarify the distribution, evolutionary and morphological relationships of four other Mico species, bridging Linnean, Wallacean, and Darwinian shortfalls in the conservation of primates in the Amazonian arc of deforestation.

Characterization of Satellite DNAs in Squirrel Monkeys genus Saimiri (Cebidae, Platyrrhini)

The genus Saimiri is a decades-long taxonomic and phylogenetic puzzle to which cytogenetics has contributed crucial data. All Saimiri species apparently have a diploid number of 2n = 44 but vary in the number of chromosome arms. Repetitive sequences such as satellite DNAs are potentially informative cytogenetic markers because they display high evolutionary rates. Our goal is to increase the pertinent karyological data by more fully characterizing satellite DNA sequences in the Saimiri genus. We were able to identify two abundant satellite DNAs, alpha (~340 bp) and CapA (~1,500 bp), from short-read clustering of sequencing datasets from S. boliviensis. The alpha sequences comprise about 1% and the CapA 2.2% of the S. boliviensis genome. We also mapped both satellite DNAs in S. boliviensis, S. sciureus, S. vanzolinii, and S. ustus. The alpha has high interspecific repeat homogeneity and was mapped to the centromeres of all analyzed species. CapA is associated with non-pericentromeric heterochromatin and its distribution varies among Saimiri species. We conclude that CapA genomic distribution and its pervasiveness across Platyrrhini makes it an attractive cytogenetic marker for Saimiri and other New World monkeys.

The bitter end: primate avoidance of caterpillar-infested trees in a central Amazon flooded forest

Animal–plant interactions are often mediated by chemical compounds. It has been widely reported that herbivore damage to plants induces chemical defenses which may then affect subsequent interactions with both invertebrate and vertebrate herbivores. Our study investigated the effects of the interaction between larvae of an unidentified nymphalid butterfly and the tanimbuca tree (Buchenavia ochroprumna Eichl.; Combretaceae) on subsequent folivory by a primate, the golden-backed uacari (Cacajao ouakary (Spix, 1823); Pitheciidae). Primate-feeding observations, records of the extent of nymphalid – B. ochroprumna interactions, and tree distribution occurred in Jaú National Park, Amazonas State, Brazil. The values of Ivlev’s electivity index showed that C. ouakary strongly rejected trees infested by caterpillars (−0.68), whereas non-infested trees were highly selected by them (+0.84). Given this behavior, we suggest that C. ouakary may be deterred by (i) caterpillars, (ii) change in leaf chemical composition induced by caterpillars, or (iii) a combination of both.

Analyzing the sclerocarpy adaptations of the Pitheciidae mandible

Primates are interpreted to be ancestrally adapted to frugivory, although some modern groups show clear adaptations to other diets. Among them, pitheciids stand out for specifically predating seeds. This dietary specialization is known as sclerocarpy and refers to the extraction of seeds from surrounding hard tissues using the anterior dentition followed by the mastication of seeds by the molars. It has been proposed that Callicebus-Pithecia-Chiropotes-Cacajao represent a morphocline of increasingly specialized anatomical traits for sclerocarpic foraging. This study addresses whether there is a sclerocarpic specialization gradient in the mandibular morphology of pitheciids. Finite element analysis (FEA) was used to simulate two biting scenarios and the obtained stress values were compared between different pitheciids. Geometric morphometrics (GM) were used to display the morphological variation of this group. No support was found for the morphocline hypothesis from a biomechanical viewpoint since all pitheciins showed similar stress values and on average Chiropotes rather than Cacajao exhibited the strongest mandible. From a morphological perspective, it was found that there is indeed relative "robusticity" continuum in the pitheciid mandible for some aspects of shape as expected for the morphocline hypothesis, but this gradient could be related to other factors rather than sclerocarpic specialization. The present results are expected to contribute to a better insight regarding the ecomorphological relationship between mandibular morphology and mechanical performance among pitheciids.

The ethnoprimatology of the Maijuna of the Peruvian Amazon and implications for primate conservation

BACKGROUND

In Amazonia, primates are not only an important food source but they also hold significant cultural and symbolic value for many indigenous groups. We document the relationship between primates and community members of the Maijuna indigenous community of Sucusari in the Peruvian Amazon and describe how ethnoprimatological studies provide a better understanding of the significance of primates in people's lives. Additionally, we explore how ethnoprimatological studies can help inform and enhance primate conservation initiatives.

METHODS

Semi-structured interviews were conducted with 50 residents of the community of Sucusari to assess the classification, cultural significance and traditional uses, beliefs, ceremonies and stories of primates within the Sucusari River basin.

RESULTS

Primates play an important role in the lives of individuals in the Sucusari community. They are distinguished by their arboreal lifestyle, and among the 11 species reported in the area, seven (Lagothrix lagotricha, Alouatta seniculus, Pithecia monachus, Callicebus spp., Saimiri sciureus, Leontocebus nigricollis) are highly recognized and culturally salient. Primates are used as food, medicine, pets, domestic tools and in the production of handicrafts. They are primarily hunted for local consumption, with larger primates such as L. lagotricha being preferred. Lagothrix lagotricha was also the most commonly reported pet species and the only observed pet primate in the community during surveys. Maijuna traditional beliefs include ancestral dietary taboos for A. seniculus, which are referred to as sorcerer monkeys, but this taboo is no longer fully adhered to. Maijuna traditional stories associated with primates describe the origin of primates found in Sucusari.

CONCLUSION

Primates are embedded in the intricate sociocultural system of the community of Sucusari. Better understanding the relationship between primates and people can help to focus conservation efforts on primate species of particularly high sociocultural importance as well as ecological value, such as L. lagotricha. We highly recommend the inclusion of ethnoprimatological studies into primate conservation initiatives to accomplish more effective conservation planning, ultimately integrating the goals of biodiversity conservation with the cultural and economic needs of indigenous and local communities.

Medium/Long wavelength sensitive opsin diversity in Pitheciidae

New World primates feature a complex colour vision system. Most species have polymorphic colour vision where males have a dichromatic colour perception and females can be either dichromatic or trichromatic. The adaptive value of high allelic diversity of opsins, a light sensitive protein, found in primates' eyes remains unknown. Studies revealing the allelic diversity are important as they shed light on our understanding of the adaptive value of differences in the colouration of species and their ecologies. Here we investigate the allelic types found in Pitheciidae, an understudied New World primate family, revealing the diversity of medium/long wavelength sensitive opsins both in cryptic and conspicuous species of this primate family. We found five alleles in Cacajao, six in Callicebinae (i.e. Plecturocebus, Cheracebus, and Callicebus), four in Chiropotes, and three in Pithecia, some of them reported for the first time. Both cryptic and conspicuous species in this group presented high allelic diversity.

Highly polymorphic colour vision in a New World monkey with red facial skin, the bald uakari (Cacajao calvus)

Colour vision is highly variable in New World monkeys (NWMs). Evidence for the adaptive basis of colour vision in this group has largely centred on environmental features such as foraging benefits for differently coloured foods or predator detection, whereas selection on colour vision for sociosexual communication is an alternative hypothesis that has received little attention. The colour vision of uakaris (Cacajao) is of particular interest because these monkeys have the most dramatic red facial skin of any primate, as well as a unique fission/fusion social system and a specialist diet of seeds. Here, we investigate colour vision in a wild population of the bald uakari,C. calvus, by genotyping the X-linked opsin locus. We document the presence of a polymorphic colour vision system with an unprecedented number of functional alleles (six), including a novel allele with a predicted maximum spectral sensitivity of 555 nm. This supports the presence of strong balancing selection on different alleles at this locus. We consider different hypotheses to explain this selection. One possibility is that trichromacy functions in sexual selection, enabling females to choose high-quality males on the basis of red facial coloration. In support of this, there is some evidence that health affects facial coloration in uakaris, as well as a high prevalence of blood-borne parasitism in wild uakari populations. Alternatively, the low proportion of heterozygous female trichromats in the population may indicate selection on different dichromatic phenotypes, which might be related to cryptic food coloration. We have uncovered unexpected diversity in the last major lineage of NWMs to be assayed for colour vision, which will provide an interesting system to dissect adaptation of polymorphic trichromacy.

Dose titration of deferasirox iron chelation therapy by magnetic resonance imaging for chronic iron storage disease in three adult red bald-headed uakari (Cacajao calvus rubicundus)

Iron overload is common in lemurs and some New World nonhuman primates raised in captivity, but there is no such documentation in the red bald-headed uakari (Cacajao calvus rubicundus). This study describes postmortem documentation of severe iron storage disease in one red bald-headed uakari and the use of iron chelation with oral deferasirox in the three surviving members of the colony. Magnetic resonance imaging was used to quantify pretreatment iron burden and to follow the response to therapy in two females, 22 and 28 yr of age, and one male 33 yr of age. Baseline liver iron concentrations ranged from 16 to 23 mg/g dry weight. In humans, a liver iron concentration greater than 15 mg/g is considered severe and associated with endocrine and cardiac toxicity. The uakaris were otherwise asymptomatic, generally healthy, nonpregnant, and on a stable, low-iron diet. Quantitative magnetic resonance imaging indicated that dosage escalations up to 100 mg/kg were needed to produce meaningful reductions in iron stores. After 5 yr of therapy, two animals continue at a dosage of 100 mg/kg per day, and the third was transitioned to twice-weekly maintenance dosing because of successful de-ironing. The animals tolerated iron chelation therapy well, having stable hematologic, renal, and hepatic function profiles before, during, and after treatment. Deferasirox monotherapy may represent a therapeutic option in primates with iron storage disease when dietary measures are ineffective and phlebotomy is logistically challenging.

Primate abundance and habitat preferences on the lower Urubamba and Tambo rivers, central-eastern Peruvian Amazonia

We report information on population density, group size, and habitat preferences of primates along the lower Río Urubamba and in the Río Urubamba–Río Tambo interfluvium, in central–eastern Peruvian Amazonia, an area that has been little explored with regard to its primate fauna. During 425 km of transect walks in October–November 2008 and April–May 2009 totally 174 groups of nine primate species were encountered, the most common being Callicebus brunneus (45 groups), Saguinus imperator (41 groups), and Aotus nigriceps (26 groups). Group sizes were smallest for A. nigriceps and C. brunneus (mean of 2.8 and 2.9, respectively) and largest for Saimiri boliviensis (mean 15.6). Population densities were lowest for Lagothrix cana (3.3 individuals/km²) and highest for A. nigriceps (31.1 individuals/km²). Groups of C. brunneus, S. imperator, S. boliviensis, Cebus albifrons, and Cebus apella were most frequently (83 % of sightings) encountered in semi-dense or in open primary forest that included stands of bamboo (Guadua sarcocarpa) or where bamboo was a very common species.

Primary seed dispersal by three Neotropical seed-predating primates (Cacajao melanocephalus ouakary, Chiropotes chiropotes and Chiropotes albinasus)

The Neotropics house two guilds of large arboreal vertebrate seed predators: parrots and the pitheciin primates. Both have diets dominated by immature fruits. The possibility of members of the Pitheciinae (genera Cacajao, Chiropotes and Pithecia) acting as occasional seed dispersers has been mooted, but not experimentally shown. We combined primate behavioural data and seed germination data from three separate field studies in the Brazilian states of Amazonas and Pará to analyse patterns of post-consumption seed survivorship for seeds discarded by three pitheciin species (Cacajao melanocephalus ouakary, Chiropotes chiropotes and Chiropotes albinasus). We then calculated the frequency of dispersal events for four species eaten by C. m. ouakary. All three primate species dropped intact seeds while feeding, and 30.7% of 674 dropped seeds germinated ex situ. Undamaged seeds from unripe and ripe samples germinated (29.3% and 42.7%, respectively), and all three primate species carried some fruits up to 20 m from the parent tree before consuming them. Potential seed-dispersal events varied from 1 (Macrolobium acaciifolium) per fruiting cycle to more than 6500 (Duroia velutina), suggesting that there are differences in dispersal potential. In summary, although they are highly specialized seed predators, these primates may also act as important dispersers for some plant species, and effective dispersal is not restricted to ripe fruits, as immature fruits removed from a tree may continue to mature and the seeds later germinate, a much-neglected aspect of dispersal ecology. The possibility that similar events occur in parrots should be experimentally investigated.

Multilevel Societies in New World Primates? Flexibility May Characterize the Organization of Peruvian Red Uakaris (Cacajao calvus ucayalii)

Researchers have described multilevel societies with one-male, multifemale units (OMUs) forming within a larger group in several catarrhine species, but not in platyrhines. OMUs in multilevel societies are associated with extremely large group sizes, often with >100 individuals, and the only platyrhine genus that forms groups of this size is Cacajao. We review available evidence for multilevel organization and the formation of OMUs in groups of Cacajao, and test predictions for the frequency distribution patterns of male–male and male–female interindividual distances within groups of red-faced uakaris (Cacajao calvus ucayalii), comparing year-round data with those collected at the peak of the breeding season, when group cohesion may be more pronounced. Groups of Cacajao fission and fuse, forming subgroup sizes at frequencies consistent with an OMU organization. In Cacajao calvus ucayalii and Cacajao calvus calvus, bachelor groups are also observed, a characteristic of several catarrhine species that form OMUs. However, researchers have observed both multimale–multifemale groups and groups with a single male and multiple females in Cacajao calvus. The frequency distributions of interindividual distances for male–male and male–female dyads are consistent with an OMU-based organization, but alternative interpretations of these data are possible. The distribution of interindividual distances collected during the peak breeding season differed from those collected year-round, indicating seasonal changes in the spatial organization of Cacajao calvus ucayalii. We suggest a high degree of flexibility may characterize the social organization of Cacajao calvus ucayalii, which may form OMUs under certain conditions. Further studies with identifiable individuals, thus far not possible in Cacajao, are required to confirm the social organization.

Peruvian Red Uakaris (Cacajao calvus ucayalii) Are Not Flooded-Forest Specialists

In the literature, particularly in primatological books, the Peruvian red uakari (Cacajao calvus ucayalii) is generally considered as a species that is specialized on living in flooded forest, despite existing evidence to the contrary. Here we review all available information on habitats where Cacajao calvus ucayalii have been observed. Most sightings are from terra firme, including palm swamps, or from mixed habitats, including terra firme and flooded forest. Therefore, we conclude that the species is not a flooded-forest specialist, but is flexible in its habitat requirements and generally uses terra firme forests or a mixture of habitats. Proper recognition of habitat requirements is important for understanding the ecoethological adaptations of a species and for appropriate conservation measures.

Chromosome phylogeny of the subfamily Pitheciinae (Platyrrhini, Primates) by classic cytogenetics and chromosome painting

BACKGROUND

The New World monkey (Platyrrhini) subfamily Pitheciinae is represented by the genera Pithecia, Chiropotes and Cacajao. In this work we studied the karyotypes of Pithecia irrorata (2n = 48) and Cacajao calvus rubicundus (2n = 45 in males and 2n = 46 in females) by G- and C-banding, NOR staining and chromosome painting using human and Saguinus oedipus whole chromosome probes. The karyotypes of both species were compared with each other and with Chiropotes utahicki (2n = 54) from the literature.

RESULTS

Our results show that members of the Pitheciinae have conserved several chromosome forms found in the inferred ancestral Platyrrhini karyotype (associations of human homologous segments 3a/21, 5/7a, 2b/16b, 8a/18, 14/15a and 10a/16a). Further, the monophyly of this subfamily is supported by three chromosomal synapomorphies (2a/10b, an acrocentric 15/14 and an acrocentric human 19 homolog). In addition, each species presents several autapomorphies. From this data set we established a chromosomal phylogeny of Pitheciinae, resulting in a single most parsimonious tree.

CONCLUSIONS

In our chromosomal phylogeny, the genus Pithecia occurred in a more basal position close to the inferred ancestor of Platyrrhini, while C. c. rubicundus and C. utahicki are closely related and are linked by exclusive synapomorphies.

Social behavior in fission-fusion groups of red uakari monkeys (Cacajao calvus ucayalii)

Primates living in large groups that divide to forage must have social systems compatible with this mode of living. Uakari monkeys (Cacajao spp.) live in large groups and exhibit a form of fission-fusion grouping, but their social organization is poorly understood. We present some of the first data on social behavior for this genus based on a study on Cacajao calvus ucayalii. They traveled in multimale multifemale groups of highly variable sizes, with bachelor units on the periphery. Adult males were affiliative, and adult females associated with more than one adult male. Adult females typically traveled with their dependent offspring and an older juvenile within the group. In parties of two or more males, individuals engaged in previously unreported display behaviors and acted together to aggressively chase other males. Breeding was seasonal, and mating occurred away from other group members. We speculate on the social organization of C. calvus ucayalii, in which dispersal may be bisexual and peripheral males are affiliative with one another. Affiliated males appear to cooperate in fighting and displaying to other males for access to females during the breeding season.

The golden-backed uacari on the upper Rio Negro, Brazil

The golden-backed uacari Cacajao melanocephalus ouakary is one of South America's least-known monkeys. Listed as Vulnerable by the IUCN, it lives in remote areas of north-western Amazonia, as yet relatively unaffected by ecologically disruptive economic and technological activities. It inhabits swamp forests on black-water rivers during the main fruiting season and may move to dry land forests at other times of the year. The authors' survey showed that the animal was still common in the vicinity of subsistence communities, but is subject to heavy hunting pressure. Although the political situation in the area and the region's remoteness make it difficult to implement conservation plans, the authors propose a possible basis for a conservation plan for the golden-backed uacari and its habitat.

Multi-directional chromosome painting maps homologies between species belonging to three genera of New World monkeys and humans

We mapped chromosomal homologies in two species of Chiropotes (Pitheciini, Saki Monkeys) and one species of Aotus (Aotinae, Owl Monkey) by multi-directional chromosome painting. Human chromosome probes were hybridized to Chiropotes utahicki, C. israelita and Aotus nancymae metaphases. Wooly Monkey chromosome paints were also hybridized to Owl Monkey metaphases. We established Owl Monkey chromosome paint probes by flow sorting and reciprocally hybridized them to human chromosomes. The karyotypes of the Bearded Saki Monkeys studied here are close to the hypothesized ancestral platyrrhine karytoype, while that of the Owl Monkey appears to be highly derived. The A. nancymae karyotype is highly shuffled and only three human syntenic groups were found conserved coexisting with 17 derived human homologous associations. A minimum of 14 fissions and 13 fusions would be required to derive the A. nancymae karyotype from that of the ancestral New World primate karyotype. An inversion between homologs to segments of human 10 and 16 suggests a link between Callicebus and Chiropotes, while the syntenic association of 10/11 found in Aotus and Callicebus suggests a link between these two genera. Future molecular cytogenetic work will be needed to determine whether these rearrangements represent synapomorphic chromosomal traits.

Morphologic, karyotypic, and molecular evidence of a new form of Chiropotes (primates, pitheciinae)

Morphologic, karyotypic, and molecular analyses were carried out in 25 specimens of a distinct morph of Chiropotes (henceforth termed Chiropotes sp.) obtained from a number of localities in the Brazilian Amazon. Pelage coloration clearly distinguishes the collected specimens and all other known species of this genus. A distinct karyotype was described for Chiropotes sp. It differs from C. satanas chiropotes by two pericentric inversions, and from C. satanas utahicki by three, which suggests that these taxa are reproductively isolated. Morphometric analyses did not show significant differentiation between these Chiropotes taxa. Molecular analyses confirmed the monophyly of the subfamily Pitheciinae and genera Chiropotes, Cacajao, and Pithecia (the latter appearing as the most basal lineage of the pithecine clade). The genetic distances between C. s. utahicki and Chiropotes sp. from Rio Negro were greater than those between three recognized species of Pithecia, but smaller than those between Cacajao calvus and Cacajao melanocephalus. The most appropriate name for Chiropotes sp. from Rio Negro is C. israelita. This species, C. s. chiropotes, and C. s. utahicki are allopatric. Pelage coloration, karyotype, and molecular analysis strongly indicate that C. chiropotes, C. utahicki, and Chiropotes israelita deserve species status.

A comparison of phenotypic variation and covariation patterns and the role of phylogeny, ecology, and ontogeny during cranial evolution of new world monkeys

Similarity of genetic and phenotypic variation patterns among populations is important for making quantitative inferences about past evolutionary forces acting to differentiate populations and for evaluating the evolution of relationships among traits in response to new functional and developmental relationships. Here, phenotypic co variance and correlation structure is compared among Platyrrhine Neotropical primates. Comparisons range from among species within a genus to the superfamily level. Matrix correlation followed by Mantel's test and vector correlation among responses to random natural selection vectors (random skewers) were used to compare correlation and variance/covariance matrices of 39 skull traits. Sampling errors involved in matrix estimates were taken into account in comparisons using matrix repeatability to set upper limits for each pairwise comparison. Results indicate that covariance structure is not strictly constant but that the amount of variance pattern divergence observed among taxa is generally low and not associated with taxonomic distance. Specific instances of divergence are identified. There is no correlation between the amount of divergence in covariance patterns among the 16 genera and their phylogenetic distance derived from a conjoint analysis of four already published nuclear gene datasets. In contrast, there is a significant correlation between phylogenetic distance and morphological distance (Mahalanobis distance among genus centroids). This result indicates that while the phenotypic means were evolving during the last 30 millions years of New World monkey evolution, phenotypic covariance structures of Neotropical primate skulls have remained relatively consistent. Neotropical primates can be divided into four major groups based on their feeding habits (fruit-leaves, seed-fruits, insect-fruits, and gum-insect-fruits). Differences in phenotypic covariance structure are correlated with differences in feeding habits, indicating that to some extent changes in interrelationships among skull traits are associated with changes in feeding habits. Finally, common patterns and levels of morphological integration are found among Platyrrhine primates, suggesting that functional/developmental integration could be one major factor keeping covariance structure relatively stable during evolutionary diversification of South American monkeys.

Primate natal coats: a preliminary analysis of distribution and function

Pelage coloration of infants was compiled for 138 species of primates. Three functional hypotheses--alloparental, infant defense, and paternity cloak--for primate natal coats are tested. Neonatal pelage contrasted with adult pelage in over half of the species examined. Subtle or inconspicuous contrast was more common than flamboyant contrast. Natal coats began to change at 5.7 weeks and disappeared by 18.0 weeks postpartum on average. The first body part to lose natal coloration was the head and/or dorsum in the majority of species. Functional analyses provided no support for the only published hypothesis--alloparental--while providing partial support for two new hypotheses--infant defense and paternity cloak. A significant association between testes weight and natal coat contrast supports a link between mating system and infant contrast. This is discussed in terms of infanticide avoidance. Natal coats are proposed to be categorically differentiated into inconspicuous and flamboyant types, not differentiated by a continuous gradation, such as color. Subspecific differentiation and patterns of shared ancestry are assessed.

The role of phylogeny and behavioral competition in the evolution of coexistence among primates

No analysis of coexistence among primates has ever considered phylogenetic distances and behavioral competition. The present model proposes that high levels of behavioral competition strongly incite divergence of the respective positions of sympatric species in niches, especially when these species are closely related. This divergence is then reflected in the morphologies of coexisting species (individuals exploit new dimensions of niches and their associated morphologies are selected for) and consequently in their phylogenetic distances. Sister species (defined here as those from the same subgenus or same species group) are phylogenetically closer than kin species (of the same genus but different subgenera or species groups). Accordingly, if a minimum phylogenetic distance is a condition of stable coexistence, then kin (and higher ranking) species, but not sister species, are expected to coexist in ecological communities. Moreover, the intensity of behavioral competition among coexisting species should be inversely proportional to phylogenetic distance. (Taxa are said to have high levels of behavioral competition if they display high rates of aggressive behaviors and simultaneous low rates of grooming behaviors.) To test these hypotheses, 41 ecological communities were reviewed. The conclusions are that (i) primate sister species do coexist, but very exceptionally compared with kin species (Wilcoxon's signed ranks test, p < 0.0001), suggesting that coexistence is possible provided a minimum phylogenetic distance is respected; (ii) there is a negative relationship between taxonomic distance and the rate of aggression among sympatric primates (p = 0.04) and a positive relationship between this distance and the rate of interspecific grooming behaviors (p = 0.028), supporting the hypothesis that stable coexistence is possible if sympatric species reduce and maintain low levels of behavioral competition.

Positional behavior of the white uakari (Cacajao calvus calvus)

The positional behavior and habitat use of a group of white uakaries (Cacajao calvus calvus) was observed for 6 weeks in the dry season at Lake Teiú, Brazil. Data are presented for feeding, traveling, and resting activities. The most common feeding posture is sit, followed by stand. Cacajao frequently exhibits locomotor behaviors while in feeding trees, using pronograde clamber and quadrupedal walk. The most frequently used locomotor behaviors in travel are quadrupedal walk, leap, and pronograde clamber. Quadrupedal run and drop also figure importantly in the behavioral repertoire. The most frequent resting posture was sit, followed by ventral lie. Compared to representative members of the other pitheciin genera, Pithecia and Chiropotes, Cacajao engages in more locomotion while feeding, and uses more pedal suspension. While traveling, pronograde clamber and drop are more frequently used by Cacajao. Multiple, deformable supports are used more by Cacajao than by the other pitheciins throughout all activities. Overall, the positional behavior of Cacajao is more similar to that of Chiropotes than of Pithecia. Cacajao's behavioral solutions to the problems of balance imposed by its greatly reduced tail are discussed.

A composite estimate of primate phylogeny

This paper presents an estimate of the phylogeny of all 203 species of primate. The composite tree is derived by applying a parsimony algorithm to over a hundred previous estimates, and is well resolved, containing 160 nodes. The ages of over half the clades in the tree have been estimated from information in the literature. Bootstrapping has been used to indicate the degree of certainty associated with each clade. The tree will be a useful framework for comparative biologists and shows which areas of primate phylogeny are still only sketchily known.