Ecological and reproductive variance in serum leptin in wild vervet monkeys

Leptin was originally thought to be an antiobesity hormone, but increasing evidence suggests that its ancestral role was to mobilize neuroendocrine responses to starvation. Research on wild primates is critical for interpreting the high leptin values seen in Western human populations and captive animals. This study examined natural variation in serum leptin in wild vervet monkeys (Chlorocebus aethiops), testing the hypothesis that serum leptin in vervets varies with sex, adiposity, ecology, and reproductive state. Analyses made use of a unique dataset comprised of serum and morphometric measurements obtained from vervet monkeys in four Kenyan sites differing in altitude, temperature, rainfall, and access to human foods. Leptin and gonadal steroid concentrations were analyzed in serum samples from 116 adults. Low leptin levels in males and acyclic females support the contention that levels seen in captivity are not typical for wild primates. Measures of adiposity were not correlated with serum leptin, reflecting the extremely low fat storage in wild cercopithecine primates. Associations with habitat and season, however, indicate that leptin does register ecological variation in energy balance. Leptin levels were higher in sites and seasons with higher rainfall. Moreover, leptin varied significantly with reproductive state, with higher levels in pregnant than in acyclic females. Changes in leptin with gestation stage and duration of lactation suggest that transitory and reversible elevations were an important part of its ancestral role. These data show that in this wild primate population leptin is a sensitive index of natural variation in habitat and seasonally fluctuating reproductive state.     

Social organization of wild talapoin monkeys

A troop of wild talapoins in Cameroon had 70 members including all age-sex classes. Observed between the birth season and the next mating season, it was habitually divided into subgroups. Subgroups most commonly observed were (1) adult and large juvenile males: (2) adult females with infants, small juveniles, and large juvenile females; (3) medium sized juveniles with a single adult male. Adult females and adult males were rarely sighted together and never seen to interact. From observations of caged groups, predictions are made about the changes in this organization which might be expected during the breeding season. A possible parallel with the ecologically similar squirrel monkey is suggested.     

Intragroup lethal aggression in wild spider monkeys

We report the first evidence of intragroup coalitionary aggression leading to the death of a wild young adult male spider monkey. During a long-term study of a well-habituated community at the Otoch Ma'ax Yetel Kooh reserve in Yucatan, Mexico, a young adult male sustained severe injuries repeatedly between January and March 2002. On 1 April 2002 the same male was the victim of an intragroup attack by at least one adult male that resulted in his death. We highlight several causes of intragroup aggression that may account for the killing.     

Scream-embrace displays in wild black-horned capuchin monkeys

Reintroduction of capuchin monkeys (Cebus apella) into their social group in captivity can elicit sirena screams and embraces. Captive scream-embrace displays are male biased, and females never perform sirena screams. One hypothesis is that scream-embrace displays serve a tension-reduction or reconciliatory function between males with conflicting interests. Alternatively, these displays may function to maintain strong affiliative bonds between friendly male dyads. Scream and/or embrace displays in wild Brazilian black-horned capuchins were analyzed for social and ecological contexts, behavioral components, and individuals involved. Seventy-two displays were observed during the 199-day study period. Among the 66 displays for which both members could be identified by sex, there were 42 occurrences of male-male dyads, 17 of male-female dyads, and seven of female-female dyads. Scream-embrace dyads were male-male pairs significantly more often than expected from group membership, and the alpha male was the only male to engage in scream-embrace displays with females. Female-female pairs did embrace, but never emitted sirena screams. Displays most commonly occurred in "reunion" contexts, primarily the reuniting of subgroups after hours or days out of contact, but also after intergroup encounters, and across groups in "intergroup" displays. Displays were rare, but socially contagious, and subgroup reunions could elicit multiple displays in rapid succession. Although the occurrence of screams and embraces was positively correlated, both behaviors also occurred independently, and their functions may be different. Male sirena screams may be honest advertisements of united alliances, directed toward a third party, whereas the embrace may be a risky affiliative signal, directed primarily within the dyad.     

Sexual transmission of SIVagm in wild grivet monkeys

This study reports the prevalence of simian immunodeficiency virus and the relationship of serostatus to age and sex among a wild population of Ethiopian grivet monkeys (Cercopithecus aethiops aethiops). Seropositivity paralleled patterns of sexual activity, being nearly universal in females of reproductive age, and absent in all males except those that were fully adult. One female seroconverted between two capture seasons at an age consistent with first breeding. Our findings support a predominantly sexual mode of transmission among SIV_agm infected grivets.     

Stone tools improve diet quality in wild monkeys

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Causal knowledge of predators' behaviour in wild Diana monkeys

Wild Diana monkeys, Cercopithecus diana, of Ta? forest, Ivory Coast, are preyed upon by leopards, Panthera pardus, and chimpanzees, Pan troglodytes. These two predators differ in their main hunting tactic and Diana monkeys attempt to avoid predation with two distinct antipredator strategies: conspicuous alarm-calling behaviour to leopards and silent, cryptic behaviour to chimpanzees. However, the Diana monkeys' choice of the appropriate antipredator strategy is complicated by the fact that chimpanzees themselves also fall prey to leopards. Chimpanzees give loud and conspicuous alarm screams when they detect a leopard. When these chimpanzees' leopard alarm calls were played back to different groups of Diana monkeys, in about half of the cases recipients switched from a chimp-specific cryptic response to a leopard-specific conspicuous response, suggesting that some individuals assumed the presence of a leopard. Groups whose home range was in the core area of the resident chimpanzee community were more likely to respond this way than more peripheral groups, indicating between-group differences in semantic knowledge. In a follow-up experiment, the monkeys' understanding of the chimpanzee alarm calls was further assessed with a prime-probe technique. Monkeys were primed with chimpanzee alarm calls and then, 5 min later, tested with leopard growls to see whether they were able to anticipate the presence of a leopard. Results were consistent with the hypothesis that monkeys responding cryptically to chimpanzee alarm calls did so because they were not able to understand the calls' meaning. Data are discussed with respect to three possible cognitive mechanisms, associative learning, specialized learning programmes, and causal reasoning, that could have led to causal knowledge in some individuals but not others. Copyright 2000 The Association for the Study of Animal Behaviour.     

Ecological rigidity and the hardness of selection in the wild

Hutchinson's ecological theater and evolutionary play is a classical view of evolutionary ecology—ecology provides a template in which evolution occurs. An opposing view is that ecological and evolutionary changes are like two actors on a stage, intertwined by density and frequency dependence. These opposing views correspond to hard and soft selection, respectively. Although often presented as diametrically opposed, both types of selection can occur simultaneously, yet we largely lack knowledge of the relative importance of hard versus soft selection in the wild. I use a dataset of 3000 individual gall makers from 15 wild local populations over 5 years to investigate the hardness of selection. I show that enemy attack consistently favors some gall sizes over others (hard selection) but that these biases can be fine-tuned by density and frequency dependence (soft selection). As a result, selection is hard and soft in roughly equal measures, but the importance of each type varies as species interactions shift. I conclude that eco-evolutionary dynamics should occur when a mix of hard and soft selection acts on a population. This work contributes to the rapprochement of disparate views of evolutionary ecology—ecology is neither a rigid theater nor a flexible actor, but instead embodies components of both.     

Reproductive characteristics of wild female Phayre's leaf monkeys

Understanding female reproductive characteristics is important for assessing fertility, interpreting female behavior, and designing appropriate conservation and captive management plans. In primate species lacking morphological signs of receptivity, such as most colobines, determination of reproductive parameters depends on the analysis of reproductive hormones. Here, we use fecal hormone analysis to characterize cycle patterns (N=6 females) and gestation length (N=7 females) in a group of wild Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) in Phu Khieo Wildlife Sanctuary, Thailand. We found that both fecal estrogen (fE) and progestin (fP) levels showed clear biological patterns indicative of ovulation and conception. However, because fP patterns were inadequate in determining the end of the luteal phase, we used fE rather than fP patterns to delineate menstrual cycle parameters. We found a mean cycle length of 28.4 days (N=10), with follicular and luteal phases of 15.4 (N=10) and 12.5 days (N=14), respectively. On average, females underwent 3.57 (N=7) cycles until conception. Average gestation length was 205.3 days (N=7), with fE levels increasing over the course of pregnancy. Overall, the reproductive characteristics found for Phayre's leaf monkeys were consistent with results for other colobine species, suggesting that fecal hormone monitoring, particularly for fE metabolites, can provide useful reproductive information for this species. Am. J. Primatol. 72:1073–1081, 2010. © 2010 Wiley‐Liss, Inc.     

海南红树林的海陆蛙分布与种群密度调查

为掌握海南红树林中海陆蛙(Fejervarya cancrivora)分布和种群数量状况,于2008年4～8月选择12个红树林进行了海陆蛙分布状况调查,同时采用样带法对4个调查地点的海陆蛙生境和种群密度进行了调查.结果表明,海陆蛙只分布于海南东寨港红树林国家级自然保护区、文昌清澜港红树林省级自然保护区、儋州新英港红树林...     

Universal behaviors as candidate traditions in wild spider monkeys

Candidate traditions were documented across three communities of wild spider monkeys (Ateles geoffroyi) using an a priori approach to identify behavioral variants and a statistical approach to examine differences in their proportional use. This methodology differs from previous studies of animal traditions, which used retrospective data and relied on the 'exclusion method' to identify candidate traditions. Our a priori approach increased the likelihood that behavior variants with equivalent functions were considered and our statistical approach enabled the proportional use of 'universal' behaviors, i.e., used across all communities, to be examined for the first time in any animal species as candidate traditions. Among universal behaviors we found 14 'community preferred' variants. After considering the extent to which community preferred variants were due to ecological and, to a lesser degree, genetic differences, we concluded that at least six were likely maintained through social learning. Our findings have two main implications: (i) tradition repertoires could be larger than assumed from previous studies using the exclusion method; (ii) the relative use of universal behavior variants can reinforce community membership.