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Investigations on manual laterality in non-human primates can help clarify human evolutionary origins of hand preference and cerebral cognition. Although body posture can influence primate hand preference, investigations on how posture affects hylobatid manual laterality are still in their infancy. This study focused on how spontaneous bipedal behavioral tasks affect hand preference in Hylobatidae. Ten captive northern white-cheeked gibbons (Nomascus leucogenys) were chosen as focal subjects. Unimanual grooming during sitting posture and supported bipedal posture were applied as behavioral tasks. The gibbons displayed a modest tendency on left-hand preference during sitting posture and right-hand preference during supported bipedal posture, although no group-level hand preference was detected for either posture. From the sitting to supported bipedal posture, 70% of individuals displayed different degrees of right-side deviation trends. The strength of manual laterality in the supported bipedal posture was higher than that in the sitting posture. We found significant sex differences in manual laterality during supported bipedal posture but not during sitting posture. Thus, to a certain degree, bipedal posture in N. leucogenys facilitates stronger hand preference, elicits a rightward trend in manual laterality, and produces sex-specific hand preference.

Preparation for gibbons before being released into their habitat is crucial. Thus, there is a need for readiness assessment of Javan gibbon with several criteria derived from other species of gibbons to determine individual readiness. Pre-release assessment study for Javan gibbon (Hylobates moloch) had been conducted in January – February 2014, November – December 2014, and March-April 2016 in the Javan Gibbon Center, Mount Gede Pangrango National Park, West Java, Indonesia. The objective of this research was to assess the readiness of Javan gibbon behavior prior to release. Data collection was conducted by focal animal sampling method with 5-minute interval recording time and ad libitum method. The average time allocations of Javan Gibbon activities were as follow: feeding (18.17±3.34%); moving (22.34±0.53%); resting (46.24±3.84%); socializing (10.13±4.33%); sexual activity (0.59±0.58%); and vocalizing (2.54±0.88%). The similarities of activity allocation from this study compared by wild Javan gibbons data found as follows: feeding by 33.03%, moving by 90.97%, resting by 61.52%, socializing by 38.09%, vocalizing by 75.02%, and sexual by 44.24%. Based on readiness assessment of 11 Javan gibbons, 3 individuals were considered almost ready for release, while 8 individuals were considered ready. The assessment of behaviors criteria for the readiness of Javan gibbons before release has not existed before. The results of this research are important as a recommendation for the management of wildlife rehabilitation and as a guideline in implementing the rehabilitation and reintroduction program of Javan gibbons.

Our study presents the first evidence on how target animacy impacts on manual laterality in the Hylobatidae and contributes to filling the knowledge gap between monkeys and great apes in primate evolution of emotional lateralization. Eleven captive individuals of northern white-cheeked gibbons (Nomascus leucogenys) were chosen as focal subjects. There were significantly more ambipreferent individuals than left/right-handed individuals for both inanimate (χ2(1, n = 11) = 7.364, p = 0.007) and animate (χ2(1, n = 11) = 4.455, p = 0.035) targets, meaning no significant group-level hand preference. The right hand was more frequently used than the left hand for inanimate targets whereas the left hand was more frequently used than the right hand for animate targets, although the interaction between target animacy and hand use was not significant (proportion: F1, 10 = 0.283, p = 0.607; rate: F1, 10 = 0.228, p = 0.643). Our findings in N. leucogenys could not fully support either the tool use theory or the right hemisphere hypothesis.

We surveyed Bornean white-bearded gibbon, Hylobates albibarbis, population densities in lowland and hill dipterocarp forests within the Sari Bumi Kusama and Suka Jaya Makmur logging concessions. These surveys were conducted from 20 to 30 March 2018 in Sari Bumi Kusuma areas and 14 to 24 April 2018 in Suka Jaya Makmur. We used a fixed-point count method to detect and plot morning song bouts of gibbon groups at systematically placed listening posts. At each location in Sari Bumi Kusuma and Suka Jaya Makmur, 18 listening posts were established, and 2 observers noted and plotted gibbon morning great calls. Gibbon group density was higher at Suka Jaya Makmur than at Sari Bumi Kusuma; we estimated that there were 2.29 groups per square kilometre in the former area and 1.86 groups/km2 in the latter. Since Bornean white-bearded gibbons are strictly protected by the Government of Indonesia and listed as an Endangered species by the International Union for Conservation of Nature (IUCN), we need better management practices to protect the populations of this species within production forests (outside protected areas).

Low back pain is experienced by a large number of people in western countries and may be caused and influenced by many different pathologies and psychosocial factors including disc degeneration. Disc degeneration involves the increased expression of proinflammatory cytokines and matrix metalloproteinases (MMPs) in the disc environment, which leads to the loss of extracellular matrix (ECM) and the viability of the native disc cells (DCs). Treatment approaches using growth factors and cell therapy have been proposed due to the compelling results that growth factors and mesenchymal stem cells (MSCs) can influence the degenerated discs. The aim of this study was to investigate the effects of conditioned media (CM) from human MSCs (hMSCs) and connective tissue growth factor (CTGF) and TGF-β on disc cells, and hMSCs isolated from patients with degenerative discs and severe low back pain. The aim was also to examine the constituents of CM in order to study the peptides that could bring about intervertebral disc (IVD) regeneration. DCs and hMSC pellets (approx.. 200,000 cells) were cultured and stimulated with hMSC-derived CM or CTGF and TGF-β over 28 days. The effects of CM and CTGF on DCs and hMSCs were assessed via cell viability, proteoglycan production, the expression of ECM proteins, and chondrogenesis in 3D pellet culture. To identify the constituents of CM, CM was analyzed with tandem mass spectrometry. The findings indicate that CM enhanced the cellular viability and ECM production of DCs while CTGF and the control exhibited nonsignificant differences. The same was observed in the hMSC group. Mass spectrometry analysis of CM identified >700 peptides, 129 of which showed a relative abundance of ≥2 (CTGF among them). The results suggest that CM holds potential to counter the progression of disc degeneration, likely resulting from the combination of all the substances released by the hMSCs. The soluble factors released belong to different peptide families. The precise mechanism underlying the regenerative effect needs to be investigated further, prior to incorporating peptides in the development of new treatment strategies for low back pain that is potentially caused by IVD degeneration.

Objectives Semenogelin 1 and 2 (SEMG1 and SEMG2) are known as semen coagulating proteins in primates with a repetitive structure of 60-amino acids. The number of repeats varies among species and is hypothesized to be related to the level of primate sperm competition. Gibbons until recently were thought to be monogamous primates, but it is now known that gibbon social structure is flexible. Thus, hypotheses of the relationship between the SEMGs evolution and mating systems were tested. Materials and methods The sequences of the exon 2 of the SEMG1 and SEMG2 were obtained from 50 captive gibbons comprising six species belonging to three genera (Hylobates, Symphalangus, and Nomascus). Then we quantified the levels of polymorphism and estimated rates of protein evolution by calculating d N /d S ratio. Results Several mutations that create a premature stop codon in the SEMG1 and a reduction in the repeats of the SEMG2 in the genus Hylobates were observed and may alter the coding properties for these proteins. We also found different level of nucleotide diversity in each gene and between genera. Strikingly, in Nomascus leucogenys we discovered a high d N /d S ratio in the SEMG1 and SEMG2. The Nomascus SEMG2 also showed significantly lower nucleotide diversity than the other two genera. Discussion These results are consistent with the presence of a strong positive selection in the Nomascus lineage even if the exact selective forces acting on these genes are not yet conclusively known. We were not able to demonstrate, among gibbons, unambiguous relationships between the SEMGs evolution and mating systems.

Natural hybridization has played various roles in the evolutionary history of primates. Its consequences range from genetic introgression between taxa, formation of hybrid zones, and formation of new lineages. Hylobates lar, the white-handed gibbon, and Hylobates pileatus, the pileated gibbon, are largely allopatric species in Southeast Asia with a narrow contact zone in Khao Yai National Park, Thailand, which contains both parental types and hybrids. Hybrid individuals in the zone are recognizable by their intermediate pelage and vocal patterns, but have not been analyzed genetically. We analyzed mitochondrial and microsatellite DNA of 52 individuals to estimate the relative genetic contributions of the parental species to each individual, and the amount of introgression into the parental species. We obtained fecal samples from 33 H. lar, 15 H. pileatus and four phenotypically intermediate individuals in the contact zone. Both mitochondrial and microsatellite markers confirmed distinct differences between these taxa. Both H. lar and H. pileatus contributed to the maternal lineages of the hybrids based on mitochondrial analysis; hybrids were viable and present in socially normal reproductive pairs. The microsatellite analysis identified ten admixed individuals, four F1 hybrids, which corresponded to phenotypic hybrids, and six H. lar-like backcrosses. All 15 H. pileatus samples were identified as originating from genetically H. pileatus individuals with no H. lar admixture; hence, backcrossing is biased toward H. lar. A relatively low number of phenotypic hybrids and backcrossed individuals along with a high number of parental types indicates a bimodal hybrid zone, which suggests relatively strong bias in mate selection between the species.

Centromeres are functionally conserved chromosomal loci essential for proper chromosome segregation during cell division, yet they show high sequence diversity across species. Despite their variation, a near universal feature of centromeres is the presence of repetitive sequences, such as DNA satellites and transposable elements (TEs). Because of their rapidly evolving karyotypes, gibbons represent a compelling model to investigate divergence of functional centromere sequences across short evolutionary timescales. In this study, we use ChIP-seq, RNA-seq, and fluorescence in situ hybridization to comprehensively investigate the centromeric repeat content of the four extant gibbon genera (Hoolock, Hylobates, Nomascus, and Siamang). In all gibbon genera, we find that CENP-A nucleosomes and the DNA-proteins that interface with the inner kinetochore preferentially bind retroelements of broad classes rather than satellite DNA. A previously identified gibbon-specific composite retrotransposon, LAVA, known to be expanded within the centromere regions of one gibbon genus (Hoolock), displays centromere- and species-specific sequence differences, potentially as a result of its co-option to a centromeric function. When dissecting centromere satellite composition, we discovered the presence of the retroelement-derived macrosatellite SST1 in multiple centromeres of Hoolock, whereas alpha-satellites represent the predominate satellite in the other genera, further suggesting an independent evolutionary trajectory for Hoolock centromeres. Finally, using de novo assembly of centromere sequences, we determined that transcripts originating from gibbon centromeres recapitulate the species-specific TE composition. Combined, our data reveal dynamic shifts in the repeat content that define gibbon centromeres and coincide with the extensive karyotypic diversity within this lineage.

Social primates face conflicts of interest with other partners when their individual and collective interests collide. Despite living in small, primarily bonded, groups compared to other social primates, gibbons are not exempt from these conflicts in their everyday lives. In the current task, we asked whether dyads of gibbons would solve a conflict of interest over food rewards. We presented dyads of gibbons with a situation in which they could decide whether to take an active role and pull a handle to release food rewards at a distance or take a passive role and avoid action. In this situation, the passive partner could take an advantageous position to obtain the rewards over the active partner. Gibbons participated in three conditions: a control condition with no food rewards, a test condition with indirect food rewards and a test condition with direct food rewards. In both test conditions, five rewards were released at a distance from the handle. In addition, the active individual could obtain one extra food reward from the handle in the direct food condition. We found that gibbons acted more often in the two conditions involving food rewards, and waited longer in the indirect compared to the direct food condition, thus suggesting that they understood the task contingencies. Surprisingly, we found that in a majority of dyads, individuals in the active role obtained most of the payoff compared to individuals in the passive role in both food conditions. Furthermore, in some occasions individuals in the active role did not approach the location where the food was released. These results suggest that while gibbons may strategize to maximize benefits in a competitive food task, they often allowed their partners to obtain better rewards. Our results highlight the importance of social tolerance and motivation as drivers promoting cooperation in these species.

A study on the variation in great-call structure of hybrid gibbons (Hylobates agilis x H. muelleri) was conducted throughout the headwaters of the Barito River in Central Kalimantan, Indonesia. A total of 88 females from 22 sites were recorded between September– November, 2004 and May– August, 2005. A detailed spectrographic analysis was made on 469 great-calls, which revealed that six of the 45 variables measured could accurately differentiate between agile and Muller’s gibbons: (1) Number of great-call notes, (2) Great-call rate of emission, (3) Number of climax notes, (4) Climax rate of emission, (5) Mid-climax note duration, and (6) Inter-climax note interval. Of these, only the variable "climax rate of emission" could reliably distinguish between the calls of agile (n = 23 females), Muller’s (n = 14 females) and hybrid gibbons (n = 51 females). A coefficient of variation indicated that intra-individual variation in great-call structure was low for each of the six variables. Non-parametric tests revealed that intra-population variation in great-call structure varied significantly (P< 0.05). A discriminant function analysis found that great-calls could be correctly assigned to the individual that produced them at a rate higher than would be expected by chance (cross-validated classification rate: hybrid = 81.9%; agile = 54.4%; Muller’s = 52.4%). There was a significant (P < 0.05) level of inter-population variation in great-call structure. The cross-validated correct assignment rate was 94%, indicating that the agile, Muller’s, and hybrid populations could be reliably distinguished by the two functions of the discriminant function analysis. One of the main variables in each of the two functions was "climax rate of emission". Within the hybrid population, females located on the western side of the hybrid zone had a slower climax rate of emission (mean = 2.07 notes/s) than those located on the eastern side (mean = 4.55 notes/s). This finding is likely due to a larger proportion of agile genes on the western side of the hybrid zone, and a larger proportion of Muller’s genes on the eastern side. It appears that the average climax rates of emission on both sides of the hybrid zone have increased since last surveyed by Mather (1992), indicating that the rate of emission of hybrid great-calls is accelerating. There was a significant level of variation between mother-daughter pairs, one generally having a faster climax rate of emission than the other. It appeared that the regular participation of daughters in song bouts was to practice their own song, rather than learn that of their mother. Female neighbours also varied significantly in their call structure. The wide range of inter-individual variation indicates that great-call structure is inherited and not learnt. The hybrid zone appears to have increased in size since it was last surveyed (Mather, 1992). Fifteen of the 29 females recorded between the western side of the Busang River and the northern side of the Joloi River were hybrids. These females were sparsely distributed from the village of Parahau down to the northern banks of the Joloi River. They had a faster climax rate of emission (range = 0.67-4.89 notes/s) than the agile gibbons in the same region (range = 0.37-0.65 notes/s). It is likely that limited hybridisation has long been present in this region, but that hybrids have become more abundant than when last surveyed.

Forest structure, defined as the three-dimensional vertical and horizontal distribution of canopy vegetation, has a great influence on the distribution patterns and abundance of forest primates. The complexity of this structural canopy produces a diverse range of microhabitats and distinct ecological niches, allowing ecologically similar species to coexist. Degradation of forests through anthropogenic factors significantly alters forest structure, and arboreal species such as gibbons are particularly vulnerable to these changes because of their reliance on canopy for survival. We investigated how forest structural variables influenced the density of two sympatric gibbon species (siamangs, Symphalangus syndactylus and lar gibbons, Hylobates lar) in Sikundur, a historically disturbed tropical lowland forest in north Sumatra. We used auditory sampling to establish group density in 10 locations and assessed structural characteristics of forest within 4–6 vegetation plots in each location. Lar gibbon group densities were 0.53–3.10 groups/km2 and siamang group densities were lower, with 0.0–1.0 groups/km2. The densities of both species were positively influenced by median height of first bole and the percentage of canopy connectivity. Lar gibbon group density was positively related to large (diameter at breast height 30–100 cm), tall (20–25 m) trees with a large crown area (100–300 m2), while siamang group density showed no significant relationships with these variables. These findings show canopy connectivity and height to first bole are significant structural variables for the continued presence of both gibbon species although, ecologically similar species can be influenced by different levels of structural disturbance. This canopy structural variation between sympatric species existing in the same ecosystem allows for home range overlap, low interspecific competition, and coexistence.

Parasitic nematodes of Oesophagostomum spp., commonly known, as 'nodular worms' are emerging as the most widely distributed and prevalent zoonotic nematodes. Oesophagostomum infections are well documented in African non-human primates; however, the taxonomy, distribution and transmission of Oesophagostomum in Asian non-human primates are not adequately studied. To better understand which Oesophagostomum species infect Asian non-human primates and determine their phylogeny we analysed 55 faecal samples from 50 orangutan and 5 gibbon individuals from Borneo and Sumatra. Both microscopy and molecular results revealed that semi-wild animals had higher Oesophagostomum infection prevalence than free ranging animals. Based on sequence genotyping analysis targeting the Internal transcribed spacer 2 of rDNA, we report for the first time the presence of O. aculeatum in Sumatran apes. Population genetic analysis shows that there is significant genetic differentiation between Bornean and Sumatran O. aculeatum populations. Our results clearly reveal that O. aculeatum in free-ranging animals have a higher genetic variation than those in semi-wild animals, demonstrating that O. aculeatum is circulating naturally in wildlife and zoonotic transmission is possible. Further studies should be conducted to better understand the epidemiology and dynamics of Oesophagostomum transmission between humans, non-human primates and other wild species and livestock in Southeast Asia.

Sleep in the primate order remains understudied, with quantitative estimates of sleep duration available for less than 10% of primate species. Even fewer species have had their sleep synchronously quantified with meteorological data, which have been shown to influence sleep-wake regulatory behaviors. We report the first sleep duration estimates in two captive gibbon species, the Javan gibbon (Hylobates moloch) and the pileated gibbon (Hylobates pileatus) (N = 52 nights). We also investigated how wind speed, humidity, temperature, lunar phase, and illumination from moonlight influence sleep-wake regulation, including sleep duration, sleep fragmentation, and sleep efficiency. Gibbons exhibited strict diurnal behavior with little nighttime activity and mean total average sleep duration of 11 h and 53 min for Hylobates moloch and 12 h and 29 min for Hylobates pileatus. Gibbons had notably high sleep efficiency (i.e., time score asleep divided by the time they spent in their sleeping site, mean of 98.3%). We found illumination from moonlight in relation to lunar phase and amount of wind speed to be the strongest predictors of sleep duration and high-quality sleep, with increased moonlight and increased wind causing more fragmentation and less sleep efficiency. We conclude that arousal threshold is sensitive to nighttime illumination and wind speed. Sensitivity to wind speed may reflect adaptations to counter the risk of falling during arboreal sleep.

Gibbons (Family Hylobatidae) are a suitable model for exploring hybridization in pair-living primates as several species form hybrid zones. In Khao Yai National Park, Thailand, white-handed gibbons (Hylobates lar) and pileated gibbons (Hylobates pileatus) are distributed parapatrically and hybridize in a narrow zone. Their phenotypic characteristics suggest limited inter-species gene flow, although this has never been assessed. To uncover the history and degree of gene flow between the two species, we studied the genetic structure of gibbons in the hybrid zone by analyzing fecal DNA samples, phenotypic characteristics, vocalizations and individuals’ social status. We determined eight autosomal single nucleotide variant (SNV) loci, and mitochondrial DNA (mtDNA) and Y-chromosomal haplotypes of 72 gibbons. We compared these markers with reference types of wild pureblood white-handed gibbons (n = 12) in Kaeng Krachan National Park and pureblood pileated gibbons (n = 4) in Khao Soi Dao Wildlife Sanctuary. Autosomal genotypic analyses confirmed the various levels of mixed ancestry for several adult gibbons with or without atypical phenotypic traits in Khao Yai National Park. In some other adult gibbons, the mixed ancestry was not detected in either autosomal SNVs or their phenotypic traits but the mtDNA. Both male and female adult hybrids formed reproductive units mainly with a phenotypic pureblood partner and many of them produced offspring. Taken together, our results suggest that once hybridization occurs, white-handed-pileated-gibbon hybrids can reproduce with either parental species and that the backcrossing and thus introgression may occur in successive generations, with no drastic changes in phenotypic appearance.

Clostridium ventriculi (syn. Sarcina ventriculi) is a Gram-positive opportunistic pathogen with sarcina morphology. In the case of gastrointestinal disorders, the treatment is often empirical. Due to the common occurrence in primates and the potential risk of dysbiosis; the antibiotic susceptibility screening of C. ventriculi strains isolated from guenon monkeys and crested gibbons to 58 antibiotics was performed to reduce potentially ineffective antibiotic use in case of disease. Isolates were found to be susceptible to the majority of the tested antibiotics, mainly to (fluoro)quinolones, macrolides, penicillins, and tetracyclines. The susceptibility profiles were similar despite the hosts. Tested strains showed also natural resistance to a few antibiotics on the genus level. Detected in vitro antibiotic efficiency is consistent with documented human treatment cases.

Javan gibbon (Hylobates moloch) is one of endemic primates in Java Island, which listed as endangered and facing the high risk of extinction. Conservation efforts need to be taken immediately in regard to the decrease of this species population. One of aspects that support conservation effort is data on daily activity of this species. The aim of this study was to determine the daily activities of Javan gibbon juvenile at Citalahab Forest Gunung Halimun Salak National Park. We used focal sampling method to collect behavioral data and recording the activity of each individual Javan gibbon by continuous recording. Average time the daily activities of the three groups is 9 hours 56 minutes. Percentage of daily activity from the highest to the lowest is the resting (36.21%), feeding (33.33%), moving (23.05%), socializing (4.94%) and undetected (2.47%). Mostly social activities that do by javan gibbon is play with most frequently performed is wrestling. Javan gibbon in Cikaniki – Citalahab used 11 species as food resource. There are four types of trees used as sleeping tree over the research. The dominant tree strata for sleeping tree is strata A (over 30 m).

Within a month, all five individuals of a pileated gibbon (Hylobates pileatus) family presented the same symptoms: diarrhoea, vomiting and severe apathy. During this first outbreak, three of them died acutely and a fourth died during another outbreak 7 months later. Extensive virology, bacteriology and parasitology undertaken on faeces did not reveal any pathogen. Haematology and extensive biochemistry did not demonstrate any obvious medical disorder. Necropsy revealed a severe proliferative enteropathy, and rare argyrophilic bacteria were noted within the lumen of hyperplastic colonic glands on histology with silver staining. Specific faecal PCR was positive for Lawsonia intracellularis infection. These combined elements led to a strong suspicion of L intracellularis epizooty, despite the absence of large numbers of argyrophilic bacteria, as usually expected in this disease process. L intracellularis has mostly been described in pigs even if reported in a broad range of mammalian species including primates. L intracellularis may be underdiagnosed in zoos as it requires a faecal PCR for identification and silver staining for histological visualisation.

Establishing protected areas (PAs) is an essential strategy to reduce biodiversity loss. However, many PAs do not provide adequate protection due to poor funding, inadequate staffing and equipment, and ineffective management. As part of China's recent economic growth, the Chinese government has significantly increased investment in nature reserves over the past 20 years, providing a unique opportunity to evaluate whether PAs can protect threatened species effectively. We compiled data from published literature on populations of gibbons (Hylobatidae), a threatened taxon with cultural significance, that occurred in Chinese reserves after 1980. We evaluated the ability of these PAs to maintain gibbon habitat and populations by comparing forest cover and human disturbance between reserves and their surrounding areas and modeling the impact of reserve characteristics on gibbon population trends. We also assessed the perspective of reserve staff concerning PA management effectiveness through an online survey. Reserves effectively protected gibbon habitat by reducing forest loss and human disturbance; however, half the reserves lost their gibbon populations since being established. Gibbons were more likely to survive in reserves established more recently, at higher elevation, with less forest loss and lower human impact, and that have been relatively well studied. A larger initial population size in the 1980s was positively associated with gibbon persistence. Although staff of all reserves reported increased investment and improved management over the past 20-30 years, no relationship was found between management effectiveness and gibbon population trends. We suggest early and emphatic intervention is critical to stop population decline and prevent extinction.Efectos de las Áreas Protegidas sobre la Supervivencia de Gibones Amenazados en China Resumen El establecimiento de áreas protegidas (APs) es una estrategia esencial para la reducción de la pérdida de la biodiversidad. Sin embargo, muchas APs no proporcionan una protección adecuada debido a un mal financiamiento, personal y equipamientos inadecuados y un manejo poco efectivo. Como parte del reciente crecimiento económico en China, el gobierno del país ha incrementado significativamente la inversión en las reservas naturales durante los últimos 20 años, proporcionando así una oportunidad única para evaluar si las APs pueden proteger a las especies amenazadas de manera efectiva. Recopilamos datos de la literatura publicada sobre las poblaciones de gibones (Hylobatidae), un taxón amenazado que cuenta con importancia cultural, que se presentaron en las reservas chinas después de 1980. Evaluamos la habilidad de estas APs para mantener el hábitat y las poblaciones de gibones al comparar la cobertura del bosque y la perturbación humana entre las reservas y las áreas vecinas y al modelar el impacto de las características de la reserva sobre las tendencias poblacionales de los gibones. También evaluamos la perspectiva del personal de la reserva con respecto a la efectividad en el manejo de la AP por medio de una encuesta en línea. Las reservas protegieron efectivamente al hábitat de los gibones mediante la reducción de la pérdida del bosque y de la perturbación humana; sin embargo, la mitad de las reservas perdieron su población de gibones desde su establecimiento. Los gibones tuvieron mayores probabilidades de sobrevivir en las reservas establecidas más recientemente, a una elevación más alta, con menor pérdida de bosque y menor impacto humano, y las cuales han sido relativamente bien estudiadas. Un tamaño de población inicial mayor durante la década de 1980 estuvo asociado positivamente con la permanencia de los gibones. Aunque el personal de todas las reservas reportó un incremento en la inversión y mejoras en el manejo durante los últimos 20-30 años, no encontramos una relación entre la efectividad en el manejo y las tendencias poblacionales de los gibones. Sugerimos que una intervención temprana y empática es crítica para detener la declinación poblacional y prevenir la extinción.建立保护区是缓解生物多样性丧失的重要手段。然而, 因为缺乏资金、人员和设备, 以及缺乏有效的管理, 很多保护区并没有为生物多样性提供足够的保护。过去 20 年中, 随着中国经济的发展, 中国政府极大地增加了对保护区的投入, 为我们提供了独特的机会来评估保护区能否有效地保护濒危物种。长臂猿科的物种均属于濒危物种, 在中国具有重要的文化意义。我们从已发表的文献中收集了 1980 年后生活在保护区内的长臂猿种群相关数据, 并评估了这些保护区能否维持长臂猿的种群和栖息地。我们比较了保护区与其周边地区的森林覆盖率和人为干扰, 并使用模型分析了影响长臂猿种群变化的保护区特征。同时, 我们通过线上问卷调查了保护区员工对于其所在保护区管理有效性的评价。结果显示, 保护区通过减少森林丧失和人为干扰, 能够有效地保护长臂猿的栖息地; 然而同时, 长臂猿在将近一半的保护区中消失了。长臂猿更多地存活在在较近成立的, 具有更高的海拔、更少的森林丧失、更少的人为干扰, 以及更多的科学研究的保护区中, 80 年代起始种群更大的长臂猿种群也更有可能存活下来。虽然所有保护区的员工均表示在过去 20-30 年间, 其所在保护区的投入和管理有效性均在增加, 但我们没有发现管理有效性和长臂猿种群变化趋势之间存在相关性。我们建议, 对濒危物种进行尽早且有力的干预, 对于制止种群下降、防止灭绝具有重要的作用。.

Captive breeding is vital for primate conservation, with modern zoos serving a crucial role in breeding populations of threatened species and educating the general public. However, captive populations can experience welfare issues that may also undermine their reproductive success. In order to enhance the well-being of endangered zoo primates, we conducted a study to assess the effects of a new scent enrichment programme on captive red-ruffed lemurs (Varecia rubra), black howler monkeys (Alouatta caraya), siamangs (Symphalangus syndactylus), Lar gibbons (Hylobates lar) and orangutans (Pongo pygmaeus pygmaeus). We combined behavioural observations and faecal endocrinology analyses to evaluate the effects of a series of essential oils (benzoin, lavender, lemongrass) on five captive troops (N = 19) housed at Dudley Zoo & Castle and Twycross Zoo (UK). We recorded observations of natural species-specific and abnormal stress-related behaviours for 480 hr using instantaneous scan sampling. We collected 189 faecal samples and measured the faecal cortisol concentrations using radioimmunoassay. We found a significant effect of the scent enrichment on behaviours, with red-ruffed lemurs and black howler monkeys reducing their social interactions, as well as red-ruffed lemurs and Lar gibbons decreasing their stress-related behaviours, after they were exposed to the series of essential oils. We also found that red-ruffed lemurs displayed a significant increase in faecal glucocorticoids following the exposure to essential oils. Our contradictory findings suggest that the effects of this series of essential oils may change depending on the species-specific social lives and olfactory repertoires of primates. In conclusion, we cannot recommend using these essential oils widely with zoo primates without additional evaluation.

Co-option of transposable elements (TEs) to become part of existing or new enhancers is an important mechanism for evolution of gene regulation. However, contributions of lineage-specific TE insertions to recent regulatory adaptations remain poorly understood. Gibbons present a suitable model to study these contributions as they have evolved a lineage-specific TE called LAVA (LINE-AluSz-VNTR-Alu(LIKE)), which is still active in the gibbon genome. The LAVA retrotransposon is thought to have played a role in the emergence of the highly rearranged structure of the gibbon genome by disrupting transcription of cell cycle genes. In this study, we investigated whether LAVA may have also contributed to the evolution of gene regulation by adopting enhancer function. We characterized fixed and polymorphic LAVA insertions across multiple gibbons and found 96 LAVA elements overlapping enhancer chromatin states. Moreover, LAVA was enriched in multiple transcription factor binding motifs, was bound by an important transcription factor (PU.1), and was associated with higher levels of gene expression in cis. We found gibbon-specific signatures of purifying/positive selection at 27 LAVA insertions. Two of these insertions were fixed in the gibbon lineage and overlapped with enhancer chromatin states, representing putative co-opted LAVA enhancers. These putative enhancers were located within genes encoding SETD2 and RAD9A, two proteins that facilitate accurate repair of DNA double-strand breaks and prevent chromosomal rearrangement mutations. Co-option of LAVA in these genes may have influenced regulation of processes that preserve genome integrity. Our findings highlight the importance of considering lineage-specific TEs in studying evolution of gene regulatory elements.

When resources are limited and defensible, inter-group encounters in animals are often of aggressive nature. Individuals can participate in inter-group encounters to defend mates, infants, and food resources, but also to attract out-group individuals for additional mating opportunities. Since inter-group conflicts have mainly been studied in group-living species, we examined the mate, infant, and food resource defense and mate attraction hypotheses in pair-living Javan gibbons (Hylobates moloch) in Gunung Halimun-Salak National Park, Indonesia. To this end, we investigated factors influencing male and female participation and outcome of encounters (i.e., win vs. lose). We observed 234 complete encounters between three habituated and five unhabituated gibbon groups over 43 months, of which 72% were aggressive. Males were the main participants and they were more likely to participate when cycling females or dependent infants were present, supporting the mate and infant defense hypotheses. Males were also more likely to participate when more fruits were available, contradicting the food resource defense hypothesis. Females participated by singing more often when they were cycling and when there were singing opponents, suggesting an advertisement function of their reproductive status through songs. The probability of winning an inter-group encounter was only higher when cycling females were present, supporting the mate defense hypothesis. The intensity of space use or aggression level had no effect on the outcome of inter-group encounters. Our results highlight that mate and infant defense are crucial for male Javan gibbons, especially in view of their pair-living system, long interbirth intervals, and slow infant development. While animal groups interact aggressively with each other to defend valuable resources, they can also interact to increase additional mating opportunities. Here, we examined male and female participation and the outcomes of inter-group encounters in a wild pair-living primate, the Javan gibbon. Crucially, we found that the presence of cycling females had a significant impact on male participation, female singing, and the outcome of encounters. Our findings suggest that Javan gibbon females may advertise their reproductive status through singing during inter-group encounters while Javan gibbon males rather participate to defend their mates and infants.

Understanding how niche differences evolve in ecologically similar species and how these differences are maintained is a fundamental question in ecology. We studied resource partitioning and niche overlap between the hoolock gibbon (Hoolock hoolock) and other frugivorous vertebrates from April 2016 to January 2018 in Satchari National Park, Sylhet, Bangladesh. We examined the differences in their diet, niche breadth, niche overlap, and characterization of patch use. We recorded feeding events of gibbons and other frugivorous vertebrates using ad libitum sampling. Gibbons consumed 76 plant species including 32 non-fig fruits and 14 figs. Twenty-one competing frugivorous vertebrate species shared 10-70% of their food species with hoolocks. Competition for fruits was intense among gibbons, macaques, and hornbills, as fruits comprised more than 50% of their diet. The niche breadth of the gibbons varied across seasons. It was lowest during the rainy season (B

Gibbons in the genus Hylobates, which live in Southeast Asia, show great diversity, comprising seven to nine species. Natural hybridisation has been observed in the species contact zones, although the roles played by hybridisation and introgression in the evolution of these species remain unclear. To uncover the divergence history and the contributions of hybridisation and introgression to the evolution of Hylobates, random amplicon sequencing-direct (GRAS-Di) analysis was employed to genotype 47 gibbons, representing eight species from three genera. After quality filtering, over 300,000 autosomal single-nucleotide variant (SNV) sites were identified. The SNV-based autosomal phylogeny, together with the mitochondrial phylogeny, supported a divergence pattern beginning approximately 4.3 million years ago. First, the mainland species, H. pileatus and H. lar, consecutively diverged from the Sundaic island species. Second, H. moloch, in Java (and likely H. klossii, in the Mentawai Islands) diverged from the other species. Third, H. muelleri, in Borneo, and H. agilis/H. albibarbis, in Sumatra and southwestern Borneo, diverged. Lastly, H. agilis and H. albibarbis diverged from each other. The Patterson’s D-statistics indicated significant introgression between H. lar and H. pileatus, between H. lar and H. agilis, and between H. albibarbis and H. muelleri, and weak introgression was identified between H. moloch and H. albibarbis, and between H. moloch and H. muelleri abbotti, suggesting incomplete reproductive barriers among Hylobates species and that hybridisation and introgression occur whenever the distribution ranges contact. Some candidates for introgressed genomic regions were detected, and the functions of these would be revealed by further genome-wide studies.

Setiawan A, Simanjuntak C, Saumanuk I, Tateburuk D, Dinata Y, Liswanto D, Rafiastanto A. 2020. Distribution survey of Kloss’s Gibbons (Hylobates klosii) in Mentawai Islands, Indonesia. Biodiversitas 21: 2224-2232. The aim of this study was to assess the population density, distribution, habitats, and threats of Kloss’s gibbon (Hylobates klossii) in the Mentawai Islands, Indonesia. In 2011-2012 we conducted a survey on Siberut Island, outside of the National Park, as well as a short visit to Sipora, North Pagai, and South Pagai. From March to September 2017, we surveyed once again some previous localities on the Siberut and Sipora islands to keep up to date with recent developments on the ground. On Siberut we used an auditory sampling method through fixed point counts, combined with line transects, to estimate the gibbon densities. In total, 113-morning calls were recorded from 13 Listening Points; 75 of these were used for density calculations. We recorded 35 individuals based on direct sightings during 66.4 km of transect distance walked. We found 13 localities outside of Siberut National Park that still have Kloss's gibbons; densities varied between 1.04group/km2 to 4.16 group/km2. No gibbons were found and heard during the short survey in Sipora and South Pagai, though we found a group of gibbons in North Pagai. Our 2017 survey revealed massive habitat changes in South Siberut. Previously existing forest localities in South Siberut were gone due to road construction, agriculture expansion, and logging.

Evidence for compression, or minimization of code length, has been found across biological systems from genomes to human language and music. Two linguistic laws—Menzerath's Law (which states that longer sequences consist of shorter constituents) and Zipf's Law of abbreviation (a negative relationship between signal length and frequency of use)—are predictions of compression. It has been proposed that compression is a universal in animal communication, but there have been mixed results, particularly in reference to Zipf's Law of abbreviation. Like songbirds, male gibbons ( Hylobates muelleri ) engage in long solo bouts with unique combinations of notes which combine into phrases. We found strong support for Menzerath's Law as the longer a phrase, the shorter the notes. To identify phrase types, we used state-of-the-art affinity propagation clustering, and were able to predict phrase types using support vector machines with a mean accuracy of 74%. Based on unsupervised phrase type classification, we did not find support for Zipf's Law of abbreviation. Our results indicate that adherence to linguistic laws in male gibbon solos depends on the unit of analysis. We conclude that principles of compression are applicable outside of human language, but may act differently across levels of organization in biological systems.

Yersinia enterocolitica (YE) bioserotype 1B/O:8 (YE 1B/O:8) was identified in routine culture of a variety of zoo species housed at Omaha's Henry Doorly Zoo and Aquarium (OHDZA) from April to July 2011. Animal cases representing 12 species had YE detected from 34 cases during routine fecal monitoring and/or during postmortem examination: Coquerel's sifakas (Propithecus coquereli, two cases), black & white (BW) ruffed lemurs (Varecia variegata variegata, six cases), red ruffed lemurs (Varecia rubra, seven cases), white handed gibbon (Hylobates lar albimana, one case), black lemurs (Eulemur macaco, three cases), mongoose lemurs (Eulemur mongoz, two cases), African hunting dogs (Lycaon pictus, five cases), agile gibbons (Hylobates agilis, three cases), siamangs (Hylobates syndactylus, two cases), colobus monkey (Colobus angolensis palliates, one case), argus pheasant (Argusianus argus, one case), and orangutan (Pongo pygmaeus, one case). Most species were not symptomatic; however, three symptomatic cases in Coquerel's sifakas (two) and a white handed gibbon (one) showed clinical signs of diarrhea and lethargy that resulted in death for the Coquerel's sifakas. One unexpected death also occurred in a BW ruffed lemur. To the authors' knowledge, this is the first report of YE 1B/O:8 in such a large variety of zoo species. The source of the YE could not be identified, prompting the initiation of a diseases surveillance program to prevent further cases for the species that are sensitive to YE. To date, no additional cases have been identified, thus suggesting a single introduction of the YE 1B/O:8 strain into the zoo environment.

Primates live in very diverse environments and, as a consequence, show an equally diverse locomotor behaviour. During locomotion, the primate hand interacts with the superstrate and/or substrate and will therefore probably show adaptive signals linked with this locomotor behaviour. Whereas the morphology of the forearm and hand bones have been studied extensively, the functional adaptations in the hand musculature have been documented only scarcely. To evaluate whether there are potential adaptations in forelimb musculature to locomotor behaviour, we investigated the forearm and hand musculature of the highly arboreal gibbons (including Hylobates lar, Hylobates pileatus, Nomascus leucogenys, Nomascus concolor, Symphalangus syndactylus) and compared this with the musculature of the semi-terrestrial rhesus macaques (Macaca mulatta) by performing complete and detailed dissections on a sample of 15 unembalmed specimens. We found that the overall configuration of the upper arm and hand musculature is highly comparable between arboreal gibbons and semi-terrestrial macaques, and follows the general primate condition. Most of the identified differences in muscle configuration are located in the forearm. In macaques, a prominent m. epitrochleoanconeus is present, which potentially helps to extend the forearm and/or stabilize the elbow joint during quadrupedal walking. The m. flexor carpi radialis shows a more radial insertion in gibbons, which might be advantageous during brachiation, as it can aid radial deviation. The fingers of macaques are controlled in pairs by the m. extensor digiti secondi et tertii proprius and the m. extensor digiti quarti et quinti proprius-a similar organization can also be found in their flexors-which might aid in efficient positioning of the hand and fingers on uneven substrates during quadrupedal walking. In contrast, extension of the little finger in gibbons is controlled by a separate m. extensor digiti minimi, whereas digits 2 to 4 are extended by the m. extensor digitorum brevis, suggesting that simultaneous extension of digits 2-4 in gibbons might be important when reaching or grasping an overhead support during brachiation. In conclusion, the overall configuration of the forelimb and hand musculature is very similar in gibbons and macaques, with some peculiarities which can be linked to differences in forelimb function and which might be related to the specific locomotor behaviour of each group. ispartof: Journal Of Anatomy vol:237 issue:4 pages:774-790 ispartof: location:England status: published

Over the course of their long research history, a plethora of scientific names have been applied to the different species of apes (Hominoidea). Although numerous authors, past and present, have attempted to reconstruct hominoid nomenclatural history in detail, it appears that parts of it, mostly concerning the lesser apes or gibbons, still remain overlooked. Here I show thatSimia NanodesLichtenstein, 1791 is a senior synonym ofSimia MolochAudebert, 1797, otherwise regarded as the oldest binomen applicable to the Javan gibbon. However, sinceSimia Nanodesfailed to enter common usage, these names are subject to a reversal of precedence as defined by Article 23.9 of the International Code of Zoological Nomenclature.Simia MolochAudebert, 1797 must be maintained as anomen protectum, resulting inHylobates moloch(Audebert, 1797) staying the valid name of the species. Simia NanodesLichtenstein, 1791 is declared anomen oblitum. In compliance with this, I provide a complete scientific synonymy of the Javan gibbon and comment on its early research history.

The adaptive functions of food transfer from parents to their offspring have been explained mainly by two mutually non-exclusive hypotheses: the nutritional and informational hypotheses. In this study, we examined the functions of food transfer in wild Javan gibbons (Hylobates moloch) by testing these hypotheses from both infants’ and mothers’ perspectives. We observed 83 cases of food solicitations that resulted in 54 occasions of food transfers in three groups over a 19-month period in Gunung Halimun-Salak National Park, Indonesia. Infants initiated all solicitations directed at their mothers with one solicitation towards a father. Food solicitation rate decreased as infant age increased and ceased before weaning. As predicted by the informational hypothesis, infants solicited more food items difficult to obtain and preferred by their parents. On the contrary to the nutritional hypothesis, infants solicited low-quality items more often than high-quality items. Mothers did not change probability of food transfer according to the food characteristics or infant age. Hence, our results suggest that the primary function of food transfer from mother to infant Javan gibbons seems to be information transfer rather than nutritional aids, similarly to great apes.

Objectives We tested whether patterns of intraspecific variation in catarrhine vertebral shape are consistent with developmental or functional predictions. Intraspecific variation was compared across column regions, morphological features, and species. Transitional regions and later ossifying morphological features were predicted to exhibit increased variation. The lumbosacral region, biomechanically important morphological features, and species with high locomotor demand and/or dedicated pronogrady were predicted to exhibit decreased variation. Materials and methods We used a modified Levene's test to compare intraspecific variation in dimensions of the neural canal, vertebral bodies, and spinous and transverse processes in lower thoracic to proximal sacral vertebrae. The sample included all hominoid genera and one cercopithecoid (Chlorocebus). Results We found little difference in variation across regions of the vertebral column. In hominoids, vertebral body dimensions were the least variable, neural canal dimensions the most variable, with spinous and transverse processes generally intermediate. Among species, there was a general though not always significant pattern for Chlorocebus to exhibit the least variation, followed by Homo or Hylobates. Discussion Patterns of variation across morphological features may reflect the complex interaction of functional constraints, developmental timing, and/or variable biomechanical forces. Pongo's elevated variation in spinous process length suggests a release from functional constraint, consistent with its suspensory locomotion and reduced spinous processes. Interspecific differences in vertebral variation based on locomotor demand or posture are generally consistent with patterns previously reported for vertebral formula and other aspects of morphology. Future research would benefit from an expanded taxonomic sample and more detailed analyses of vertebral modularity and developmental timing.

The javan gibbon reintroduction program requires assessment of suitable habitat within release sites to assure the survival of released gibbons. We studied habitat suitability for javan gibbon beginning in April 2017, extending to June 2017 in the Mount Malabar Protected Forest (MMPF), West Java. The objectives of this study were to analyze the habitat suitability of the release site for javan gibbon in MMPF. Analysis of Geographical Information System (GIS) and Principal Component Analysis (PCA) approach were used to obtain habitat suitability values. Habitat suitability variables measured are elevation, Normalized Differential Vegetation Index (NDVI), Bareness Soil Index (BSI), distance from the road, farming, settlement, and open field. We found suitability valued areas consisting of high suitability covered 2,009.23 ha (22.31%), moderate suitability covered 2,497.46 ha (27.73%), and low suitability covered 4.499,65 ha (49.96%), from a total area ± 8.894,47 ha in MMPF.