Ateles Belzebuth Research Articles

HOW VISITATION AFFECTS THE BEHAVIOR AND WELFARE OF DIFFERENT SPECIES OF CAPTIVE AMAZONIAN PRIMATES?

This study had the purpose of understanding the effects of visitation on behavioral patterns and on the well-being of primates in captivity. Five Amazonian primate species were observed using the focal animal method: Ateles chamek, Ateles belzebuth, Ateles paniscus, Lagothrix cana, and Sapajus apella. Two categories of visitor behavioral observations were adopted - active and passive. From the total number of records, the behavior of primates could be observed in 53.7% of the notes in the presence of visitors. The behavior of the visitors in front of the cages was considered passive in 91.2% of those records. The three species of Ateles reacted in different ways in the presence and absence of visitors. The type of visitor behavior had influence on the behavior of the primate (Chi-square=22.9, p0.001). Stress indicating behaviors (CIE) represented 3.3% of the behavioral repertoire of the species (n=253 records). The primates presented a varied number of CIE, which included indexes of reduced well-being levels. A. belzebuth was ranked first as the species most affected by visitation. These results show the importance of understanding the stress effects on the behavioral pattern of captive primates in relation to visitation and other factors, leading to alternative actions for the zoo in order to improve the level of their welfare.

Color vision and niche partitioning in a diverse neotropical primate community in lowland Amazonian Ecuador.

A recent focus in community ecology has been on how within‐species variability shapes interspecific niche partitioning. Primate color vision offers a rich system in which to explore this issue. Most neotropical primates exhibit intraspecific variation in color vision due to allelic variation at the middle‐to‐long‐wavelength opsin gene on the X chromosome. Studies of opsin polymorphisms have typically sampled primates from different sites, limiting the ability to relate this genetic diversity to niche partitioning. We surveyed genetic variation in color vision of five primate species, belonging to all three families of the primate infraorder Platyrrhini, found in the Yasuní Biosphere Reserve in Ecuador. The frugivorous spider monkeys and woolly monkeys (Ateles belzebuth and Lagothrix lagotricha poeppigii, family Atelidae) each had two opsin alleles, and more than 75% of individuals carried the longest‐wavelength (553–556 nm) allele. Among the other species, Saimiri sciureus macrodon (family Cebidae) and Pithecia aequatorialis (family Pitheciidae) had three alleles, while Plecturocebus discolor (family Pitheciidae) had four alleles—the largest number yet identified in a wild population of titi monkeys. For all three non‐atelid species, the middle‐wavelength (545 nm) allele was the most common. Overall, we identified genetic evidence of fourteen different visual phenotypes—seven types of dichromats and seven trichromats—among the five sympatric taxa. The differences we found suggest that interspecific competition among primates may influence intraspecific frequencies of opsin alleles. The diversity we describe invites detailed study of foraging behavior of different vision phenotypes to learn how they may contribute to niche partitioning.

Mamíferos medianos y grandes del Espacio Territorial de Capacitación y Reincorporación (ETCR) Playa Rica, La Macarena, Meta, Colombia

Las sabanas del Yarí son una importante área biogeográfica cuya biodiversidad no ha sido explorada. Esta zona estuvo históricamente bajo el control de los grupos armados ilegales que restringían su acceso e investigación. Con el proceso de paz, las sabanas del Yarí se abrieron a la investigación, pero también a procesos antrópicos que amenazan su biodiversidad. Aquí, presentamos un listado preliminar que incluye los primeros registros de mamíferos medianos y grandes del sector noroccidental de las sabanas del Yarí, como resultado de un programa de monitoreo comunitario con excombatientes de las FARC. Reportamos 24 especies pertenecientes a 18 familias y 8 órdenes de mamíferos. Resaltamos la presencia de diez especies amenazadas incluidas Priodontes maximus, Tapirus terrestris y Ateles belzebuth. Esto representa el 96 % de los mamíferos terrestres en el río Yarí. A partir de las entrevistas semiestructuradas y notas de campo consideramos a la deforestación, el avance de la frontera agrícola, la ganadería y la caza como las principales amenazas para los mamíferos.

Reproductive seasonality in two sympatric primates (Ateles belzebuth and Lagothrix lagotricha poeppigii) from Amazonian Ecuador.

With their large body size and "slow" life histories, atelin primates are thought to follow a risk-averse breeding strategy, similar to capital breeders, in which they accumulate energy reserves in anticipation of future reproductive events such as gestation and lactation. However, given the paucity of longitudinal data from wild populations, few studies to date have been able to compare the timing of reproductive events (e.g., copulations, conceptions, and births) in relation to shifting resource availability over multiple years. We examined the reproductive patterns of two atelin species-white-bellied spider monkeys (Ateles belzebuth) and lowland woolly monkeys (Lagothrix lagotricha poeppigii)-in relation to habitat-wide estimates of fruit availability at the Tiputini Biodiversity Station (TBS) in Amazonian Ecuador. Our sample included 4 years of data on births (N = 36) and copulations (N = 170) for Lagothrix, 10 years of data on births (N = 35)and copulations (N = 74) for Ateles, and 7 years of data on ripe fruit availability. Reproductive events were distinctly seasonal. For both species, births were concentrated between May and September, a time period in which ripe fruit was relatively scarce, while inferred conceptions occurred between September and January, when ripe fruit availability was increasing and maintained at high-levels throughout the forest. Interannual variation in births was relatively stable, except for in 2016 when twice as many infants were born following a strong El Niño event that may have led to unusually high levels of fruit productivity during the 2015 breeding season. Although copulations were observed year-round, an overwhelming majority (>90% for Lagothrix and >80% for Ateles) took place between August and February when females were most likely to conceive. Collectively, these data follow the reproductive patterns observed in other atelin primates, and, as proposed by others, suggest that atelins may follow a risk-averse breeding strategy.

Calls for concern: Matching alarm response levels to threat intensities in three Neotropical primates

Various species of animals maximise energy gained through foraging by minimising excessive energy spent on nonessential activities. Avoiding predation is key for maximising an individual's lifespan, as well as that of its kin; however, anti-predation behaviours can be energetically costly. We investigated the relationship between the potential threat levels by predators, pseudo-predators, and non-predators, and the subsequent energetic cost of behavioural reactions to these threats, in the white-bellied spider monkey (Ateles belzebuth), golden-backed uacari (Cacajao ouakary), and red-nosed cuxiú (Chiropotes albinasus). We analyzed a total of 270 interactions across three independent field studies of the three primate species. Our results revealed significant differences in the behavioural response to predators and non-predators for both C. ouakary and C. albinasus, but not for A. belzebuth. In terms of risk-categorized behaviours, response to predators differed from response to non-predators (being much more intense and energy intensive), while there was no difference in response to predators versus pseudo-predators. Thus, response to potential predators represents an integral part of the time-management and defence strategies of two of the three studied species, and should be integrated into future studies of primate responses to varying levels of predation threat.

Sperm Morphology in Neotropical Primates.

Simple SummaryThe spermatozoon is a highly differentiated cell, whose morphology has been affected throughout evolution by selective forces such as the competition between the sperm of rival males (sperm competition) and the joint evolution of male and female reproductive tracts (coevolution). The study of its morphology is important when analyzing the relationships between different species. In this contribution we analyzed new specimens and produced a database with all the spermatozoa dimensions recorded to date, comprising 75 individuals from 20 species and 8 genera, representing 2 families of neotropical primates (Cebidae and Atelidae). After an evolutionary analysis, we observed two different trends for the Cebidae and Atelidae families. Narrower and shorter spermatozoa seem to be the ancestral (oldest) form for Cebidae, with an evolutionary trend toward spermatozoa with wider and larger heads in the derived (younger) species. In Atelidae, on the contrary, narrower heads are observed in the more derived groups. We analyzed these results in the context of sperm competition and mating systems in these groups. More studies are needed to improve our knowledge of the evolution of the spermatozoa in neotropical primates.The morphological and morphometric characterization of spermatozoa has been used as a taxonomic and phylogenetic tool for different species of mammals. We evaluated and compared the sperm morphometry of five neotropical primate species: Alouatta caraya, Ateles belzebuth and Ateles chamek of family Atelidae; and Cebus cay (=Sapajus cay) and Cebus nigritus (=Sapajus nigritus) of family Cebidae. After the collection of semen samples, the following parameters were measured on 100 spermatozoa from each specimen: Head Length, Head Width, Acrosome Length, Midpiece Length, Midpiece Width and Tail Length. Considering the available literature on sperm morphometry, we gathered data of 75 individuals, from 20 species, 8 genera and 2 families. These data were superimposed on a phylogeny to infer the possible direction of evolutionary changes. Narrower and shorter spermatozoa seem to be the ancestral form for Cebidae, with a trend toward wider and larger heads in derived groups. The spermatozoa of Atelidae may show an increase in total length and midpiece length. Sperm heads would have become narrower in the more derived groups of Ateles. Sperm length may increase in the more derived species in both families. Our results are discussed in the context of sperm competition and sexual selection.

Initiation of feeding by four sympatric Neotropical primates (Ateles belzebuth, Lagothrix lagotricha poeppigii, Plecturocebus (Callicebus) discolor, and Pithecia aequatorialis) in Amazonian Ecuador: Relationships to photic and ecological factors.

We examined photic and ecological factors related to initiation of feeding by four sympatric primates in the rain forest of Amazonian Ecuador. With rare exceptions, morning activities of all taxa began only after the onset of nautical twilight, which occurred 47–48 min before sunrise. The larger spider and woolly monkeys, Ateles belzebuth and Lagothrix lagotricha poeppigii, left their sleeping trees before sunrise about half the time, while the smaller sakis and titi monkeys, Pithecia aequatorialis and Plecturocebus (formerly Callicebus) discolor, did not emerge until sunrise or later. None of the four taxa routinely began feeding before sunrise. Pithecia began feeding a median 2.17 h after sunrise, at least 0.8 h later than the median feeding times of the other three taxa. The early movement of Ateles and Lagothrix, and late initiation of feeding by Pithecia are consistent with temporal niche partitioning. Among most New World primate species, all males and many females, have dichromatic color vision, with only two cone photopigments, while some females are trichromats with three cone photopigments. Current evidence indicates that the dichromats have a foraging advantage in dim light, which could facilitate utilization of twilight periods and contribute to temporal niche partitioning. However, in our study, dichromatic males did not differentially exploit the dim light of twilight, and times of first feeding bouts of female Ateles and Lagothrix were similar to those of males. First feeding bouts followed a seasonal pattern, occurring latest in May-August, when ripe fruit abundance and ambient temperature were both relatively low. The most frugivorous taxon, Ateles, exhibited the greatest seasonality, initiating feeding 1.4 h later in May-August than in January-April. This pattern may imply a strategy of conserving energy when ripe fruit is scarcer, but starting earlier to compete successfully when fruit is more abundant. Lower temperatures were associated with later feeding of Ateles (by 26 min / °C) and perhaps Pithecia, but not Lagothrix or Plecturocebus. The potential for modification of temporal activity patterns and temporal niche partitioning by relatively small changes in temperature should be considered when predicting the effects of climate change.

Demography and life history of a group of white-bellied spider monkeys (Ateles belzebuth) in western Amazonia.

Species-specific demographic parameters and life history variables are important for understanding how individual primate taxa have adapted to evolutionary and ecological pressures and for conducting interspecific comparisons as well as for conducting population viability analyses and for managing captive populations. Here, we describe results from a 12+ year study of the demographic dynamics of a wild group of white-bellied spider monkeys (Ateles belzebuth belzebuth) living near the Tiputini Biodiversity Station in a largely pristine rainforest in western Amazonia. Across the study period, group size varied between 25 and 37 individuals, and there was a clearly female-biased sex ratio within all age classes. Females were the dispersing sex, as 19 females born into the group disappeared close to reaching adult body size and were presumed to have emigrated, while seven subadult or adult females joined the group during the study period. We estimated the age of dispersal for females at 5.9 ± SD 0.4 years (N = 13). Our study confirms that males are the philopatric sex, as all natal males have remained in the group and some have begun to reproduce, while no males have immigrated. Males began ranging independently from their mothers at ∼4.5 years of age and began copulating with adult females by the age of ∼5 years. Females had long inter-birth intervals (44.2 ± SD 7.8 months; range: 32-64 months, N = 21). Based on our data, female spider monkeys might have longer life spans than males, as only one out of six adult males but 9 out of 11 adult females present in the group in mid 2005 were still present in January 2018. The slow development and extended life histories of wild spider monkeys pose significant challenges for the ability of these primates to cope with habitat degradation and hunting throughout their geographical distribution.

Deep incursion and use of a mineral lick within a neighboring territory by a group of white-bellied spider monkeys (<i>Ateles belzebuth</i>) in eastern Ecuador


 
 
 One convergent aspect of the societies of chimpanzees and spider monkeys is the fact that members of a social group jointly conduct territorial boundary patrols and raids into home ranges of neighboring groups. Boundary patrols are usually perpetrated by subgroups of adult and subadult males who travel in silence into neighboring territories. Only rarely do females participate in these incursions. Moreover, for spider monkeys living in the western Amazon, mineral licks (or ‘salados’) seem to be key areas where animals descend to the ground and consume water and soils, most likely to acquire minerals not readily available in their diet. Based on 10 years of behavioral research, here we document a unique case in which most members of one group of white-bellied spider monkeys (Ateles belzebuth) collectively made a deep incursion into a neighboring group’s territory and used a mineral lick well within a that group ́s range. This particular event raises the intriguing questions of what knowledge group members might possess about locations of key resources in adjacent territories, how they acquire this knowledge, and what motivates the use of those resources, especially when groups have other mineral licks they can frequent within their own territories. Although occasional deep incursions into other group’s ranges may be part of the repertoire of intergroup interactions engaged in by wild spider monkeys, the underlying explanation behind the decision to visit and consume soil from mineral licks in neighboring territories remains largely unexplained.
 
 

Diversidad y estado de conservación de la mastofauna terrestre del municipio de San Vicente del Caguán, Caquetá, Colombia

Objetive : Determine the diversity and conservation status of land mammals of the municipality of San Vicente del Caguan, Caqueta, Colombia. Methodology : The research was conducted in 4 vegetation patches of characterized by high dense forest od solid land, gallery forest, secondary vegetation and weedy grasses surrounded by clean pasture. Visual sampling technique was used in day runs for recording arboreal mam- mals and ightless; for bats catching 4 mist nets were installed in each patch by ad libitum way, between 17:30 to 23:00. The obtained information was analyzed by an accumulation curve, Margaleft s diversity index, Shanon H, Simpson, Dominance and evenness, similarity and correspondence analysis. Results : 105 individuals of mammals, distributed in eight orders, 15 families and 23 species were recorded. the greatest diversity (H) and richest (M) was founded in high dense forest of solid land patches surrounded by grasses and secondary vegetation and greater evenness in Gallery Forest surrounded by clean pastu- re. Three species of special interest for conservation were identi ed, Tapirus terrestris , Ateles belzebuth y Lagothrix lagothricha. Conclusions : The study area is a place of high mammals diversity, with forest remaining shelter which are important areas for mammals. It is so important to make conservation initia- tives, because stress conditions (hunting, wood and oil extraction) are dangerous for the maintenance of this community in the department of Caqueta.

Genetic consequences of seed dispersal to sleeping trees by white-bellied spider monkeys

Frugivorous animals frequently generate clumped distributions of seeds away from source trees via ‘destination-based’ dispersal processes. For example, use of traditional sleeping trees by white-bellied spider monkeys Ateles belzebuth generates high densities of seeds of a preferred food source, the palm Oenocarpus bataua, at these sites. Little is known about the maternal seed source diversity and population genetic metrics of seed pools encountered at these sites. Given the repeated use of sleeping trees over time, and the fluid social organization and wide ranging movements exhibited by spider monkeys, we predicted that O. bataua seed pools beneath sleeping trees would be characterized by relatively high values of maternal seed source diversity and standard metrics of genetic diversity. Contrary to these expectations, we found relatively low average maternal seed source diversity beneath each of 6 sleeping trees we studied (weighted mean α = 3.74), but considerable variation in diversity of maternal seed sources between sleeping trees (range = 1.75–10.1) and high heterogeneity in standard genetic diversity measures between sleeping trees. There was no evidence for overlap in maternal seed sources between sleeping tree sites (δ = 1.0), resulting in significant genetic differentiation (Fst = 0.055–0.319) between these sites. Observed variation between sleeping trees could not be explained by the number of individual spider monkeys whose core home ranges included a given tree, nor by distance to a central mineral lick, a focal point of spider monkey activity. These findings suggest that spider monkey seed dispersal to sleeping trees is spatially restricted, perhaps because the animals visit sleeping trees at the end of the day and therefore only disperse O. bataua fruits that they ingest late in the day. These results add to our growing appreciation of the ways frugivore behavior mechanistically shapes seed dispersal outcomes.

Crying Tapir: The Functionality of Errors and Accuracy in Predator Recognition in Two Neotropical High-Canopy Primates

Predation is often considered to be a prime driver in primate evolution, but, as predation is rarely observed in nature, little is known of primate antipredator responses. Time-limited primates should be highly discerning when responding to predators, since time spent in vigilance and avoidance behaviour may supplant other activities. We present data from two independent studies describing and quantifying the frequency, nature and duration of predator-linked behaviours in 2 high-canopy primates, Ateles belzebuth and Cacajao ouakary. We introduce the concept of ‘pseudopredators' (harmless species whose appearance is sufficiently similar to that of predators to elicit antipredator responses) and predict that changes in behaviour should increase with risk posed by a perceived predator. We studied primate group encounters with non-primate vertebrates across 14 (Ateles) and 19 (Cacajao) months in 2 undisturbed Amazonian forests. Although preliminary, data on both primates revealed that they distinguished the potential predation capacities of other species, as predicted. They appeared to differentiate predators from non-predators and distinguished when potential predators were not an immediate threat, although they reacted erroneously to pseudopredators, on average in about 20% of the responses given toward other vertebrates. Reacting to pseudopredators would be interesting since, in predation, one error can be fatal to the prey.

Twinning in titis (<i>Callicebus coimbrai</i>): stretching the limits of biparental infant caregiving?

No abstract

A Novel Use of Camera Traps to Study Demography and Life History in Wild Animals: A Case Study of Spider Monkeys (Ateles belzebuth)

* * ? ** * ** * * *** * **** * ** ? *? ** * * * * **** * ***** * ** ? *? * * * * * ********* * **** * * * * * * * ? *? * * * * * * ********* ? *? * * * * * * * * * ******** * ** * ***** * ****** * ** * * ? * ? *?? * * * * * * * * * * * * ******* * ***** * * * ** * **** * * ******* * * * ****** * * ** * * * * ?* * ? * * ** * ********** * * * ?* * ? * * ** * ********* * * * * ** * *** * ******** * * * * * * * * * * * * * * *** * ** * **** * *** * * ? * * * *** * *** * ******** * *** * ******** ???? * ********** * **** * ** * ** * *** * **** * **** * ** * **** * *** * * * * ** * **** * *** * * * ** * * * * * ******** * *

Response of frugivorous primates to changes in fruit supply in a northern Amazonian forest.

Few attempts have been made to understand how spatiotemporal changes in fruit supply influence frugivores in tropical forests. The marked spatiotemporal variation in fruit supply can affect frugivore abundance and distribution, but studies addressing the effects of this variation on primates are scarce. The present study aimed to investigate how the spatiotemporal distribution of fruits influences the local distribution of three frugivorous primates in the eastern part of the Maracá Ecological Station, a highly seasonal Amazonian rainforest. Specifically, it was hypothesised that primate distribution will track changes in fruit supply, resulting that sites with high fruit availability should be heavily used by primates. During a 1-year study, fruit supply (ground fruit surveys) and primate density (line-transects) were monitored in twelve 2 km-long transects at monthly intervals. Fruit supply varied seasonally, being low during the dry season. The density of Ateles belzebuth was positively related to fruit supply during fruit shortage, but Cebus olivaceus and Alouatta macconnelli did not follow the same pattern. The supply of Sapotaceae fruit was an important component determining local distribution of A. belzebuth during the overall fruit shortage. Highly frugivorous primates such as A. belzebuth respond to seasonal decline in fruit supply by congregating at places with high fruit supply in this forest, particularly, those with many individuals of species of Sapotaceae. This study underscores the importance of small-scale spatiotemporal changes of fruit supply as a key component of frugivorous primate ecology in highly seasonal environments.

Ecological factors predictive of wild spider monkey (Ateles belzebuth) foraging decisions in Yasuní, Ecuador.

Because fruiting trees are uncommon in tropical forests, frugivorous primates experience selective pressure to incorporate knowledge of where to find feeding trees, what to expect when they arrive there, and when they can return after depleting a tree. I investigated these abilities in wild spider monkeys (Ateles belzebuth) in Yasuní, Ecuador, by analyzing the characteristics of feeding trees that drive foraging decisions. Foraging data were derived from four 2-week follows of focal adult females, conducted between May and December 1999, during which I measured and mapped all trees in which the focal subject fed, feeding bout duration, and the number of conspecifics feeding simultaneously with the focal. Taking into account the order in which feeding trees were visited across each follow, I analyzed each foraging decision from the second week of a follow, treating all previously visited trees as options for visits. I scored each option tree in terms of nine ecological variables, including the distance from the decision to each location tree, DBH, recent feeding time and mean feeding times for the focal and other monkeys present, and the interval in hours between the foraging decision and the most recent visit to each option tree. I then examined the predictive strength of the model using logistic regression analysis, comparing characteristics of selected trees to those not selected. The overall model successfully predicted trees selected by focal monkeys (r(2) = 0.27). Monkeys preferentially moved to nearby, large canopy trees, in which previous feeding success was high, and which were visited after an interval of 3.5 days. Interval mattered most for medium and large trees, but did not predict selection for trees <10 cm DBH. Despite the large home range and large numbers of trees, Yasuní spider monkeys appeared to integrate spatial, value, and temporal information when deciding where to feed.

MOLECULAR TYPING OF Giardia duodenalis ISOLATES FROM NONHUMAN PRIMATES HOUSED IN A BRAZILIAN ZOO

Giardia infections in captive nonhuman primates (NHP) housed at a Brazilian zoo were investigated in order to address their zoonotic potential. Fresh fecal samples were collected from the floors of 22 enclosures where 47 primates of 18 different species were housed. The diagnosis of intestinal parasites after concentration by sedimentation and flotation methods revealed the following parasites and their frequencies: Giardia (18%); Entamoeba spp. (18%); Endolimax nana (4.5%); Iodamoeba spp. (4.5%); Oxyurid (4.5%) and Strongylid (4.5%). Genomic DNA extracted from all samples was processed by PCR methods in order to amplify fragments of gdh and tpi genes of Giardia. Amplicons were obtained from samples of Ateles belzebuth, Alouatta caraya, Alouatta fusca and Alouatta seniculus. Clear sequences were only obtained for the isolates from Ateles belzebuth (BA1), Alouatta fusca (BA2) and Alouatta caraya (BA3). According to the phenetic analyses of these sequences, all were classified as assemblage A. For the tpi gene, all three isolates were grouped into sub-assemblage AII (BA1, BA2 and BA3) whereas for the gdh gene, only BA3 was sub-assemblage AII, and the BA1 and BA2 were sub-assemblage AI. Considering the zoonotic potential of the assemblage A, and that the animals of the present study show no clinical signs of infection, the data obtained here stresses that regular coproparasitological surveys are necessary to implement preventive measures and safeguard the health of the captive animals, of their caretakers and of people visiting the zoological gardens.

Primate Surveys in the Marañón-Huallaga Landscape, Northern Peru with Notes on Conservation

With about 50 species and subspecies, the diversity of primates in Peru is amongst the highest in the world. Primate field surveys, however, are still scarce for many areas. Peru's northern forests lie at the heart of the Tropical Andes and are home to four of the country's endemic primates: Aotus miconax, Callicebus oenanthe, Oreonax flavicauda, and Saguinus leucogenys. We present here an overview of results from more than five years of primate surveys in northern Peru. Surveys were carried out in the valleys and intervening highlands between the ríos Marañón and Huallaga in the departments of Amazonas, La Libertad, Huánuco and San Martín. Data were gathered between March 2007 and October 2012 from 36 locations at 26 sites. Surveys were carried out as part of biological inventories in proposed conservation areas. In all, 14 species were recorded from 11 genera. The presence or absence of a species was largely determined by altitude. The four endemic species were present in the majority of survey sites. The most common species encountered were Oreonax flavicauda, Ateles belzebuth, Cebus yuracus, and Aotus miconax. The highest species diversities were found at lower altitudes further from human development, although some species previously registered in these regions were not encountered. All areas visited suffered from at least some anthropogenic disturbance, with the majority showing high levels of habitat disturbance, deforestation and hunting.

A comparison of computer‐generated and naturally occurring foraging patterns in route‐network‐constrained spider monkeys

The attribution of goal-directed behavior to observations of primate foraging and ranging requires that simpler explanations for observed behavior patterns be eliminated. Computer-generated simulations of non-goal-directed foraging behavior can be used as null models for higher complexity cognitive foraging, and can provide quantifiable data against which to compare the observed behavioral patterns in wild primates. In this paper, we compare the results of two variations of computer simulated null models with observed foraging behavior of wild spider monkeys (Ateles belzebuth). One model simulates monkeys searching using a modified random-walk model in which monkeys alternate 100-m steps with turn angles derived from observed behavior. The second model constrains travel to an observed route system derived from observations of wild spider monkeys. Simulated monkeys in each model searched among increasing densities of feeding trees ranging from 10 to 1,000. We compared travel distance, travel directness, and accuracy of starting direction for each feeding tree discovered for the two models. We then compared these results with those derived from observations of wild spider monkeys. Route-model monkeys traveled shorter distances and more directly to feeding trees than did randomly foraging monkeys, and discovered trees in the direction they started more often. Observed spider monkeys outperformed simulated monkeys from both models in all variables, allowing us to reject the null hypothesis that observed foraging and ranging behavior could be explained by non-goal-directed travel.

Bimodal evolution of the killer cell Ig-like receptor (KIR) family in New World primates

The immunoglobulin-like receptor (KIR) gene family in New World primates (Platyrrhini) has been characterized only in the owl monkey (Aotus sp.). To gain a better understanding of the KIR system in Platyrrhini, we analyzed a KIR haplotype in Ateles geoffroyi, and sequenced KIR complementary DNAs (cDNAs) from other three Atelidae species, Ateles hybridus, Ateles belzebuth, and Lagothrix lagotricha. Atelidae expressed a variable set of activating and inhibitory KIRs that diversified independently from their Catarrhini counterparts. They had a unique mechanism to generate activating receptors from inhibitory ones, involving a single nucleotide deletion in exon 7 and a change in the donor splice site of intron 7. The A. geoffroyi haplotype contained at least six gene models including a pseudogene, two coding inhibitory receptors, and three coding activating receptors. The centromeric region was in a tail-to-tail orientation with respect to the telomeric region. The owl monkey KIR haplotype shared this organization, and in phylogenetic trees, the centromeric genes clustered together with those of A. geoffroyi, whereas their telomeric genes clustered independently. KIR cDNAs from the other Atelidae species conformed to this pattern. Signatures of positive selection were found in residues predicted to interact with the major histocompatibility complex. Such signatures, however, primarily explained variability between paralogous genes but not between alleles in a locus. Atelidae, therefore, has expanded the KIR family in a bimodal fashion, where an inverted centromeric region has remained relatively conserved and the telomeric region has diversified by a rapid process of gene duplication and divergence, likely favored by positive selection for ligand binding.