Hylobates Lar Research Articles

Interactions between lar gibbons and pig-tailed macaques at fruit sources.

Interactions are reported between white-handed gibbons (Hylobates lar) and pig-tailed macaques (Macaca nemestrina) in Khao Yai National Park, Thailand, in which gibbons selected ripe fruit from sources before macaques arrived on 4 occasions during June and July of 1989. The macaques foraged near gibbons or from shared fruit sources during 13% of gibbon observation time. Gibbons made their presence known in fruit trees when macaques approached on 3 occasions and macaques did not enter fruit trees occupied by gibbons. An aggressive interaction is reported in which a single white-handed gibbon vigorously excluded 22-28 macaques from a rare and valuable fruit tree (Sandoricum koetjape). The observations suggest that exploitative and interference competition may exist between these species.

Comparison of Muscle Fiber Types in the M. Biceps Brachii of White-handed Gibbon and Crab-eating Monkey

Comparison of Muscle Fiber Types in the M. Biceps Brachii of White-handed Gibbon and Crab-eating Monkey

Scaling of postcranial joint size in hominoid primates

The scaling of sixteen articular dimensions in the locomotor skeleton of hominoid primates is examined with special reference to a recently proposed model of geometric similarity. Seven species are included in the analysis (gorillas, common chimpanzees, bonobos, orang-utans, siamang, lar gibbons, and modern humans of European descent); all specimens are adult individuals of known body mass (N=87). No significant sexual dimorphism in the scaling of joint size was observed. Overal results are compatible with the biomechanical model predictions of isometry, and lend additional support to the suggestion that joint stresses are of the same order of magnitude in animals differing vastly in body size and locomotor adaptations. The hindlimb and lumbosacral joints of humans, however, are consistently much larger than expected for their body mass. Full-time bipedality obviously precludes the sharing of weight support and propulsion with the forelimbs, and this fundamental difference is accurately reflected in the relative joint size of humans.

Sympatry between white-handed gibbons (Hylobates lar) and pileated gibbons (H. pileatus) in Southeastern Thailand

White-handed gibbons (Hylobates lar) are not known to occur to the east or southeast of Bangkok. The reliably documented localities ofH. lar nearest to this area are about 120 km northeast of Bangkok. There, in the Kao Yai National Park, is the only known zone of contact betweenH. lar and the pileated gibbon (H. pileatus), another species of the so-calledlar group. Unpublished documents dating from 1925 indicate, however, that sympatry between these two species may also have existed in the region of Sriracha, about 80 km southeast of Bangkok. Therefore, a large zone of overlap in the distribution of the two species may originally have existed. In most parts of this hypothetical zone, gibbon habitat appears to have been destroyed, with the Khao Yai Park possibly representing the last remnant of the once large contact zone.

Homosexual behaviour in wild white-handed gibbons (Hylobates lar)

Homosexual mounting in apes and prosimians is rare. Male-male mounting was observed between an adult male white-handed gibbon and an adolescent male in the same group. The behaviour is discussed in terms of the gibbon group's social structure and the development of the adolescent. It is suggested that this behaviour provides reassurance for the adolescent gibbon.

Molecular evolution of the psi eta-globin gene locus: gibbon phylogeny and the hominoid slowdown.

An 8.4-kb genomic region spanning both the psi eta-globin gene locus and flanking DNA was sequenced from the common gibbon (Hylobates lar). In addition, sequencing of the entire orthologous region from galago (Galago crassicaudatus) was completed. The gibbon and galago sequences, along with published orthologous sequences from 10 other species, were aligned. These noncoding nucleotide sequences represented four human alleles, four apes (chimpanzee, gorilla, organgutan, and gibbon), an Old World monkey (rhesus monkey), two New World monkeys (spider and owl monkeys), tarsier, two strepsirhines (galago and lemur), and goat. Divergence and maximum parsimony analyses of the psi eta genomic region first groups humans and chimpanzees and then, at progressively more ancient branch points, successively joins gorillas, orangutans, gibbons, Old World monkeys, New World monkeys, tarsiers, and strepsirhines (the lemuriform-lorisiform branch of primates). This cladistic pattern supports the taxonomic grouping of all extant hominoids into family Hominidae, the division of Hominidae into subfamilies Hylobatinae (gibbons) and Homininae, the division of Homininae into tribes Pongini (orangutans) and Hominini, and the division of Hominini into subtribes Gorillina (gorillas) and Hominina (chimpanzees and humans). The additional gibbon and galago sequence data provide further support for the occurrence of a graded evolutionary-rate slowdown in the descent of simian primates, with the slowing rate being more pronounced in the great-ape and human lineages than in the gibbon or monkey lineages. A comparison of global versus local molecular clocks reveals that local clock predictions, when focused on a specific number of species within a narrow time frame, provide a more accurate estimate of divergence dates than do those of global clocks.

A semiautomated image analysis procedure for the quantification of dental microwear

AbstractDifferent diets have been shown to leave characteristic patterns of microwear on the teeth of various mammalian species. The quantification of microwear features facilitates the comparison of taxa, and allows the discrimination of wear patterns associated with specific diets. The current study reports on a semiautomated image analysis procedure designed to expedite microwear quantification by engaging an IBM PS/2 running OS/2 Presentation Manager to compute and record the density, dimensions, and orientations of features defined by a user employing a mouse‐driven cursor. This technique is used to distinguish microwear patterns on the maxillary central incisors (I1s) of four Sumatran primate species (n=5 per taxon) with known dietary differences (Hylobates lar, Macaca fascicularis, Pongo pygmaeus, and Presbytis thomasi). However, although developed for a particular problem area, the analytical routines described are of general interest.

Group harmony in gibbons: Comparison between white-handed gibbon (Hylobates lar) and siamang (H. syndactylus)

The siamang (Hylobates syndactylus) is exceptional among gibbons in that its area of distribution almost completely overlaps those of other gibbons, namely the white-handed gibbon (H. lar) and the agile gibbon (H. agilis) of the lar group. The siamang has almost twice the body weight of the gibbons of the lar group (ca. 11 kg vs. 5–6 kg), and it has been suggested that distinct ecological and behavioural differences exist between the siamang and its two sympatric species. The siamang has been claimed to differ from the white-handed gibbon “in the closer integration and greater harmony of group life” (Chivers, 1976, p. 132). However, few quantitative data exist to support this hypothesis. In the present study, intra-group interactions in captive family groups of white-handed gibbons and siamangs (two groups of each species) were recorded by focal-animal sampling. These data failed to show a consistent association between species and most of the behavioural patterns recorded, such as frequency of aggression, percentage of successful food transfer, frequency of social grooming bouts, and duration of social grooming/animal/hr. A significant difference was found for only two of the variables: Individual siamangs in this study showed longer grooming bout durations, and made fewer food transfer attempts than lar individuals. Only the first of these two differences is consistent with the hypothesis mentioned above, whereas the lower frequency of food transfer attempts in siamangs is the opposite of what should be expected under the hypothesis. On the other hand, two of these behavioural patterns showed a significant correlation with the parameters group size and individual age: Both individuals in larger groups and younger individuals tended to show shorter grooming bouts and a smaller proportion of successful food transfers. Our findings indicate that social cohesion within these gibbon groups may be much more flexible according to and depending on social or ecological influences and less rigidly linked to specific gibbon taxa than previously assumed. A considerably larger number of gibbon groups would have to be compared to provide reliable evidence for or against species-specific differences in group cohesion. Another finding of this study—a positive correlation between the frequency of aggression and grooming—is discussed in the light of the functional interpretations commonly attributed to allogrooming behaviour in primates.

The involucrin gene of the gibbon: the middle region shared by the hominoids.

The evolution of the anthropoid involucrin gene has resulted largely from a process of vectorial addition of short tandem repeats. The coding region of the involucrin gene of the gibbon (Hylobates lar), including the segment of repeats, has been cloned and sequenced, and its repeat structure can now be compared with that of the other hominoids. In the gibbon, as in the others, repeat additions in the past can be assigned to early, middle, and late regions of the present-day segment of repeats. All 10 repeats of the gibbon early region were completed in a common anthropoid ancestor. All 17 repeats of the gibbon middle region were completed in a common hominoid ancestor. After divergence of the gibbon lineage, eight repeats were added to the middle region of the great ape-human lineages. Seven of these are shared by two to four species, according to the order of their divergences from each other. After its divergence, the gibbon lineage added a short species-specific late region. The gibbon also possesses an incomplete repeat just 3' of the early region, the only addition in this region in any hominoid. Comparison of the number of repeats added with the number of nucleotides substituted shows an inconstant relation between the two.

Molecular history of gene conversions in the primate fetal gamma-globin genes. Nucleotide sequences from the common gibbon, Hylobates lar.

Comparative and phylogenetic analyses of homologous sequences from closely related species reveal genetic events which have happened in the past and thus provide considerable insight into molecular genetic processes. One such process which has been especially important in the evolution of multigene families is gene conversion. The fetal gamma 1 and gamma 2-globin genes of catarrhine primates (humans, apes, and Old World monkeys) underwent numerous gene conversion events after they arose from a gene duplication event 25-35 million years ago. By including the gamma 1- and gamma 2-globin gene sequences from the common gibbon, Hylobates lar, the present work expands the gamma-globin data set to represent all major groups of hominoid primates. A computer-assisted algorithm is introduced which reveals converted DNA segments and provides results very similar to those obtained by site-by-site evolutionary reconstruction. Both methods provide strong evidence for at least 14 different converted stretches in catarrhine primates as well as five conversions in ancestral lineages. Features of gene conversions generalized from this molecular history are 1) conversions are restricted to regions maintaining high degrees of sequence similarity, 2) one gene may dominate in converting another gene, 3) sequences involved in conversions may accumulate changes more rapidly than expected, and 4) certain elements, such as polypurine/polypyrimidine [Y)n) and (TG)n elements, appear to be hotspots for initiating or terminating conversion events.

Eosinophilic Meningoencephalitis Due to Angiostrongylus Cantonensis as the Cause of Death in Captive Non-Human Primates

Fatal eosinophilic meningoencephalitis due to Angiostrongylus cantonensis is reported in captive non-human primates. A howler monkey (Alouatta caraya) at the Audubon Park and Zoological Gardens, New Orleans, LA, died 21 days after initial clinical symptoms. A white-handed gibbon (Hylobates lar) died at the Ardastra Gardens and Zoo, Nassau, Bahamas, 17 days after onset of symptoms. Both had access to free-ranging gastropods within the zoos. These are the first reported cases of natural infection by A. cantonensis in non-human primates in the western hemisphere.

Ancestry of a human endogenous retrovirus family

The human endogenous retrovirus type II (HERVII) family of HERV genomes has been found by Southern blot analysis to be characteristic of humans, apes, and Old World monkeys. New World monkeys and prosimians lack HERVII proviral genomes. Cellular DNAs of humans, common chimpanzees, gorillas, and orangutans, but not lesser ape lar gibbons, appear to contain the HERVII-related HLM-2 proviral genome integrated at the same site (HLM-2 maps to human chromosome 1). This suggests that the ancestral HERVII retrovirus(es) entered the genomes of Old World anthropoids by infection after the divergence of New World monkeys (platyrrhines) but before the evolutionary radiation of large hominoids.

The functional morphology of weight bearing: limb joint surface area allometry in anthropoid primates

Biomechanical scaling of long bone joint surface areas was investigated in 13 species of anthropoid primates. It was proposed that joint surface areas should scale with positive allometry with respect to body size in order to maintain relatively constant safety factors for joints in small and large animals and that modifications from the overall pattern of scaling may be expected in the limb joints of species exhibiting specialized locomotor behaviours that radically alter limb loading. Within anthropoids, the brachiating primates, white‐handed gibbons (Hylobates lar) and black‐handed spider monkeys (Ateles geoffroyi), were used to test this hypothesis. Total joint surface areas were found to scale with significant positive allometry in 11 of 12 limb joints. The observed pattern of interspecific allometry supports the hypothesis that weight bearing is a major constraint on the design of joints. This positive interspecific allometry is reflected at the intraspecific level as well, with larger joints of larger species showing significant intraspecific scaling. Suspensory species showed no significant deviations from the overall anthropoid pattern, despite their reduced compressive loading of the limb joints, even after controlling for joint mobility. These results suggest that, while evolutionary changes in locomotor behaviour that produce significant increases in loading of a joint may be accompanied by selection for increased joint surface areas, adoption of locomotor repertoires that reduce limb loading may have no selective effect on joint morphology, and joint design in these cases will reflect the biomechanics of the ancestral locomotor condition.

Functional analysis of the biceps femoris muscle during locomotor behavior in some primates

In order to investigate a correlation between morphological variations of the biceps femoris muscle and its homologues in four primate species (Japanese macaque, spider monkey, white-handed gibbon, and chimpanzee) and each type of species-specific locomotor behavior, I carried out both morphological and functional analyses of these muscles. The description of the level of insertion reveals interspecific variation is in the level of crural attachment, especially in species with a bicipital biceps femoris muscle. Electromyograms (EMGs) were induced from both the long and short head of the biceps femoris muscle during four kinds of locomotor behavior (horizontal quadrupedal walking, climbing on an inclined pole, vertical climbing, and bipedal walking). In the case of the monoceptual ischiocruralis lateralis muscle of the Japanese macaque, EMGs were induced from both the one-joint femoral part and the two-joint crural part. Though during horizontal quadrupedal locomotion the crural part of the monocipital-type muscle functioned to maintain the knee joint angle, it functioned to gain propulsive force when the kinematic load became larger, as in vertical climbing and bipedal walking. On the other hand, the long heads of the biceps femoris muscles were active in propulsion regardless of the kinematic load. But in bipedal walking, the long head muscle also acted with the short head muscle to maintain the knee joint angle. These functional features of various biceps femoris muscles of primates correlated with their species-specific locomotor behavior.

Auditory enrichment for Lar gibbons Hylobates lar at London Zoo

Auditory enrichment for Lar gibbons Hylobates lar at London Zoo

Back muscle function during bipedal walking in chimpanzee and gibbon: implications for the evolution of human locomotion.

The evolution of erect posture and locomotion continues to be a major focus of interest among paleoanthropologists and functional morphologists. To date, virtually all of our knowledge about the functional role of the back muscles in the evolution of bipedalism is based on human experimental data. In order to broaden our evolutionary perspective on the vertebral region, we have undertaken an electromyographic (EMG) analysis of three deep back muscles (multifidus, longissimus thoracis, iliocostalis lumborum) in the chimpanzee (Pan troglodytes) and gibbon (Hylobates lar) during bipedal walking. The recruitment patterns of these three muscles seen in the chimpanzee closely parallel those observed in the gibbon. The activity patterns of multifidus and longissimus are more similar to each other than either is to iliocostalis. Iliocostalis recruitment is clearly related to contact by the contralateral limb during bipedal walking in both species. It is suggested that in both the chimpanzee and gibbon, multifidus controls trunk movement primarily in the sagittal plane, iliocostalis responds to and adjusts movement in the frontal plane, while longissimus contributes to both of these functions. In many respects, the activity patterns shared by the chimpanzee and gibbon are quite consistent with recent human experimental data. This suggests a basic similarity in the mechanical constraints placed on the back during bipedalism among these three hominoids. Thus, the acquisition of habitual bipedalism in humans probably involved not so much a major change in back muscle action or function, but rather an improvement in the mechanical advantages and architecture of these muscles.

Female Primate Sexual Behavior and Conception: Are There Really Sperm to Spare? [and Comments and Reply

Female Primate Sexual Behavior and Conception: Are There Really Sperm to Spare? [and Comments and Reply

Responsiveness of a male Mueller's gibbon to his own species‐song, that of a lar gibbon, and a synthetic song of similar frequency

AbstractThe study compared the responsiveness of a captive male Mueller's gibbon to audio recordings of dawn songs of wild‐living male Mueller's gibbons and lar gibbons, and to a synthetic song constructed from screech owl vocalizations. Though wild‐caught, the subject had not been exposed to songs of his own species for at least 10 years, and in fact, only rarely performed the dawn song himself. Initially, the subject responded vigorously to all three recordings, with no preference being shown for the recording of his own species. However, a very strong preference for Mueller's vocalizations did develop following a period of concentrated and exclusive exposure to Mueller's songs.

Auditory enrichment for Lar gibbons Hylobates lar at London Zoo

Auditory enrichment for Lar gibbons Hylobates lar at London Zoo

Ecological and phytochemical diversity of arillate seeds inAglaia(Meliaceae): a study of vertebrate dispersal in tropical trees

The dispersal of ten species of equatorial rainforest tree, belonging to the genusAglaia, was studied in Malaysia and Indonesia. In three of these (Aglaiaspecies 2,A. oligocarpaandA. teysmanniana) the fruits are dehiscent capsules and the red-skinned arillate seeds are dispersed by birds. Nine species of bird, belonging to six families (Bucerotidae, Capitonidae, Corvidae, Eurylaimidae, Pycnonotidae and Sturnidae), were observed to swallow the seeds. The fruits of the remaining species are indehiscent and the seeds have a white, yellow or translucent aril. The seeds of five species (A. elliptica,A. odoratissima,A. speciosa,A. korthalsiiandA. ganggo) are dispersed by primates (includingPongo pygmaeus,Hylobates lar,Presbytis melalophusandMacaca fasicularis) and one species (A.aff.elaeagnoidea) by a civet (Paradoxurus hermaphroditus). Several species of squirrel feed on the seeds, but are thought not to be important dispersers. Published accounts suggest that pigeons (Columbidae) in West Malesia, and birds of paradise (Paradisaeidae) and cassowaries (Casuariidae) in Australasia, are also dispersal agents. The arils of six of theseAglaiaspecies and four species belonging to other genera (Tabernaemontana macrocarpa,Zingibersp.,Lansium domesticumandDurio zibethinus) were analysed for lipids, carbohydrates and amino acids. A high lipid content (27-60% dry mass) was found in arils of the bird-dispersedAglaiaseeds, those of primate-dispersed species were lower in lipids and higher in free carbohydrates (reducing sugars and sucrose).