Gibbon

Last updated

Gibbons [1] [2]
Temporal range: 13.8–0  Ma
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Pg
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Late Miocene–Recent
Hylobates lar - Kaeng Krachan WB.jpg
Lar gibbon (Hylobates lar)
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Parvorder: Catarrhini
Superfamily: Hominoidea
Family: Hylobatidae
Gray, 1870
Type genus
Hylobates
Illiger, 1811
Genera


sister: Hominidae

Distribucion hylobatidae.png
Distribution in Southeast Asia

Gibbons ( /ˈɡɪbənz/ ) are apes in the family Hylobatidae ( /ˌhləˈbtəd/ ). The family historically contained one genus, but now is split into four extant genera and 18 species. Gibbons live in subtropical and tropical rainforest from eastern Bangladesh to Northeast India to southern China and Indonesia (including the islands of Sumatra, Borneo, and Java).

Contents

Also called the lesser apes or small apes, gibbons differ from great apes (chimpanzees, bonobos, gorillas, orangutans and humans) in being smaller, exhibiting low sexual dimorphism, and not making nests. [3] Like all apes, gibbons are tailless. Unlike most of the great apes, gibbons frequently form long-term pair bonds. Their primary mode of locomotion, brachiation, involves swinging from branch to branch for distances up to 15 m (50 ft), at speeds as high as 55 km/h (34 mph). They can also make leaps up to 8 m (26 ft), and walk bipedally with their arms raised for balance. They are the fastest and most agile of all tree-dwelling, nonflying mammals. [4]

Depending on the species and sex, gibbons' fur coloration varies from dark to light brown shades, and any shade between black and white, though a completely "white" gibbon is rare.

Gibbon species include the siamang, the white-handed or lar gibbon, and the hoolock gibbons.

Etymology

The English word 'gibbon' is said to be a reborrowing from French, and folk etymology (cf. Gibbon (surname)) [5] originally from an Orang Asli word. [6]

Evolutionary history

Whole genome molecular dating analyses indicate that the gibbon lineage diverged from that of great apes around 16.8 million years ago (Mya) (95% confidence interval: 15.9 – 17.6 Mya; given a divergence of 29 Mya from Old World monkeys). [7] Adaptive divergence associated with chromosomal rearrangements led to rapid radiation of the four genera 5-7 Mya. Each genus comprises a distinct, well-delineated lineage, but the sequence and timing of divergences among these genera has been hard to resolve, even with whole genome data, due to radiative speciations and extensive incomplete lineage sorting. [7] [8] An analysis based on morphology suggests that the four genera are ordered as (Symphalangus, (Nomascus, (Hoolock, Hylobates))) [9]

Hominoidea  (hominoids, apes)
Hylobatidae
(gibbons)

Symphalangus

Nomascus

Hoolock

Hylobates

Hominidae (hominids, great apes)
Ponginae
(Orangutans)
Homininae
Gorillini
(Gorilla)
Hominini
Panina
(chimpanzees)
Hominina  (Humans)

A coalescent-based species tree analysis of genome-scale datasets suggests a phylogeny for the four genera ordered as (Hylobates, (Nomascus, (Hoolock, Symphalangus))). [10]

Hominoidea  (hominoids, apes)
Hylobatidae
(gibbons)

Hylobates

Nomascus

Hoolock

Symphalangus

Hominidae (hominids, great apes)
Ponginae
(Orangutans)
Homininae
Gorillini
(Gorilla)
Hominini
Panina
(chimpanzees)
Hominina  (Humans)

At the species level, estimates from mitochondrial DNA genome analyses suggest that Hylobates pileatus diverged from H. lar and H. agilis around 3.9 Mya, and H. lar and H. agilis separated around 3.3 Mya. [8] Whole genome analysis suggests divergence of Hylobates pileatus from Hylobates moloch 1.5-3.0 Mya. [7] The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related to the hoolock gibbons. [2]

Taxonomy

Family Hylobatidae: gibbons [1] [11] [12]

Hominoid family tree Hominoid taxonomy 7.svg
Hominoid family tree
Agile gibbon, Hylobates agilis Agilegibbon.jpg
Agile gibbon, Hylobates agilis
Siamang, Symphalangus syndactylus Suneko - shout (by).jpg
Siamang, Symphalangus syndactylus
Northern white-cheeked gibbon, Nomascus leucogenys Witwanggibbon M.jpg
Northern white-cheeked gibbon, Nomascus leucogenys
Lar gibbon (Hylobates lar) Hylobates lar sitting on a stump over water.jpg
Lar gibbon (Hylobates lar)

The family is divided into four genera based on their diploid chromosome number: Hylobates (44), Hoolock (38), Nomascus (52), and Symphalangus (50). [2] [11] There is an extinct fifth genus named Bunopithecus which is either a gibbon or gibbon-like ape. [2] An extinct sixth genus, Junzi , was identified in 2018 based on a partial skull found in China. [13]

Extant species

Extinct genera

Hybrids

Many gibbons are hard to identify based on fur coloration, so are identified either by song or genetics. [17] These morphological ambiguities have led to hybrids in zoos. Zoos often receive gibbons of unknown origin, so they rely on morphological variation or labels that are impossible to verify to assign species and subspecies names, so separate species of gibbons commonly are misidentified and housed together. Interspecific hybrids, hybrids within a genus, are also suspected to occur in wild gibbons where their ranges overlap. [18] However, no records exist of fertile hybrids between different gibbon genera, either in the wild or in captivity. [7]

Physical description

Gibbon arm skeleton (left) compared to average human male arm bone structure (right). Scapula (red), humerus (orange), ulna (yellow), and radius (blue) shown in both structures. Gibbon Arm vs. Human Arm.svg
Gibbon arm skeleton (left) compared to average human male arm bone structure (right). Scapula (red), humerus (orange), ulna (yellow), and radius (blue) shown in both structures.

One unique aspect of a gibbon's anatomy is the wrist, which functions something like a ball and socket joint, allowing for biaxial movement. This greatly reduces the amount of energy needed in the upper arm and torso, while also reducing stress on the shoulder joint. Gibbons also have long hands and feet, with a deep cleft between the first and second digits of their hands. Their fur is usually black, gray, or brownish, often with white markings on hands, feet, and face. Some species such as the siamang have an enlarged throat sac, which inflates and serves as a resonating chamber when the animals call. This structure can become quite large in some species, sometimes equaling the size of the animal's head. Their voices are much more powerful than that of any human singer, although they are at best half a human's height. [19]

Gibbon skulls and teeth resemble those of the great apes, and their noses are similar to those of all catarrhine primates. The dental formula is 2.1.2.32.1.2.3 [20] The siamang, which is the largest of the 18 species, is distinguished by having two fingers on each foot stuck together, hence the generic and species names Symphalangus and syndactylus. [21]

Behavior

Genus Hoolock Ulluk-2.jpg
Genus Hoolock

Like all primates, gibbons are social animals. They are strongly territorial, and defend their boundaries with vigorous visual and vocal displays. The vocal element, which can often be heard for distances up to 1 km (0.6 mi), consists of a duet between a mated pair, with their young sometimes joining in. In most species, males and some females sing solos to attract mates, as well as advertise their territories. [22] The song can be used to identify not only which species of gibbon is singing, but also the area from which it comes. [23]

Gibbons often retain the same mate for life, although they do not always remain sexually monogamous. In addition to extra-pair copulations, pair-bonded gibbons occasionally "divorce." [24] [25]

Gibbons are among nature's best brachiators. Their ball-and-socket wrist joints allow them unmatched speed and accuracy when swinging through trees. Nonetheless, their mode of transportation can lead to hazards when a branch breaks or a hand slips, and researchers estimate that the majority of gibbons suffer bone fractures one or more times during their lifetimes. [26] They are the fastest and most agile of all tree-dwelling, nonflying mammals. [26]

Diet

Gibbons' diets are about 60% fruit-based, [27] but they also consume twigs, leaves, insects, flowers, and occasionally bird eggs.

Genetics

Gibbons were the first apes to diverge from the common ancestor of humans and apes about 16.8 million years ago. With a genome that has a 96 percent similarity to humans, the gibbon has a role as a bridge between Old World Monkeys like macaques and the great apes. According to a study that mapped synteny (genes occurring on the same chromosome) disruptions in the gibbon and human genome, humans and great apes are part of the same superfamily (Hominoidea) with gibbons. The karyotype of gibbons, however, diverged in a much more rapid fashion from the common hominoid ancestor than other apes.

The common ancestor of hominoids is shown to have a minimum of 24 major chromosomal rearrangements from the presumed gibbon ancestor’s karyotype. To reach the common gibbon ancestor’s karyotype from today’s various living species of gibbons, it will require up to 28 additional rearrangements. Adding up, this implies that at least 52 major chromosomal rearrangements are needed to compare the common hominoid ancestor to today’s gibbons. No common specific sequence element in the independent rearrangements was found while 46% of the gibbon-human synteny breakpoints occur in segmental duplication regions. This is an indication that these major differences in humans and gibbons could have had a common source of plasticity or change. Researchers view this unusually high rate of chromosomal rearrangement that is specific in small apes like gibbons could potentially be due to factors that increase the rate of chromosomal breakage or factors that allow derivative chromosomes to be fixated in a homozygous state while mostly lost in other mammals. [28]

The whole genome of the gibbons in Southeast Asia was first sequenced in 2014 by the German Primate Center (DPZ) including Christian Roos, Markus Brameier and Lutz Walter along with other international researchers. One of the gibbons that had its genome sequenced is a white-cheeked gibbon (Nomascus leucogenys, NLE) named Asia. The team found that a jumping DNA element named LAVA transposon (also called gibbon-specific retrotransposon) is unique to the gibbon genome apart from humans and the great apes. The LAVA transposon increases mutation rate and thus is supposed to have contributed to the rapid and greater change in Gibbons in comparison to their close relatives, which is critical for evolutionary development. The very high rate of chromosomal disorder and rearrangements (such as duplications, deletions or inversions of large stretches of DNA) due to the moving of this large DNA segment is one of the key features that are unique to the gibbon genome.

A special feature of the LAVA transposon is that it positioned itself precisely between genes that are involved in chromosome segregation and distribution during cell division, which results in a premature termination state leading to an alteration in transcription. This incorporation of the jumping gene near genes involved in chromosome replication is thought to make the rearrangement in the genome even more likely, leading to a greater diversity within the gibbon genera. [29]

In addition, there are characteristic genes in the gibbon genome which had gone through a positive selection and are suggested to give rise to specific anatomical features for gibbons to adapt to their new environment. One of them is TBX5, which is a gene that is required for the development of the front extremities or forelimbs such as long arms. The other is COL1A1, which is responsible for the development of collagen, a protein that is directly involved with the forming of connective tissues as well as bone and cartilage development. [29] This gene is thought to have a role in gibbons having stronger muscles. [30]

Researchers have found a coincidence between major environmental changes in southeast Asia about 5 million years ago that caused a cyclical dynamic of expansions and contracitons of their forest habitat; an instance of radiation experienced by the gibbon genera. This may have led to the development of a suite of physical characteristics, distinct from their great ape relatives, to adapt to their habitat of dense, canopy forest. [29]

These crucial findings in genetics have contributed to the use of gibbons as a genetic model for chromosome breakage and fusion, which is a type of translocation mutation. The unusually high number of structural changes in the DNA and chromosomal rearrangements could lead to problematic consequences in some species. [31] Gibbons, however, not only seemed to be free from problems but let the change help them effectively adapt to their environment. Thus, gibbons are organisms that genetics research could be focused on to broaden the implications to human diseases related to chromosomal changes like cancer, such as chronic myeloid leukemia. [32] [33]

Conservation status

Most species are either endangered or critically endangered (the sole exception being H. leuconedys , which is vulnerable), primarily due to degradation or loss of their forest habitats. [34] On the island of Phuket in Thailand, a volunteer-based Gibbon Rehabilitation Center rescues gibbons that were kept in captivity, and are being released back into the wild. [35] The Kalaweit Project also has gibbon rehabilitation centers on Borneo and Sumatra. [36] [37]

The IUCN Species Survival Commission Primate Specialist Group announced 2015 to be the Year of the Gibbon [38] and initiated events to be held around the world in zoos to promote awareness of the status of gibbons. [39]

In traditional Chinese culture

Two gibbons in an oak tree by the Song dynasty painter Yi Yuanji Yi-Yuanji-Two-gibbons-in-an-oak-tree.jpg
Two gibbons in an oak tree by the Song dynasty painter Yì Yuánjí

The sinologist Robert van Gulik concluded gibbons were widespread in central and southern China until at least the Song dynasty, and furthermore, based on an analysis of references to primates in Chinese poetry and other literature and their portrayal in Chinese paintings, the Chinese word yuán (猿) referred specifically to gibbons until they were extirpated throughout most of the country due to habitat destruction (circa 14th century). In modern usage, however, yuán is a generic word for ape. Early Chinese writers viewed the "noble" gibbons, gracefully moving high in the treetops, as the "gentlemen" (jūnzǐ, 君子) of the forest, in contrast to the greedy macaques, attracted by human food. The Taoists ascribed occult properties to gibbons, believing them to be able to live for several hundred years and to turn into humans. [40]

Gibbon figurines as old as from the fourth to third centuries BCE (the Zhou dynasty) have been found in China. Later on, gibbons became a popular object for Chinese painters, especially during the Song dynasty and early Yuan dynasty, when Yì Yuánjí and Mùqī Fǎcháng excelled in painting these apes. From Chinese cultural influence, the Zen motif of the "gibbon grasping at the reflection of the moon in the water" became popular in Japanese art, as well, though gibbons have never occurred naturally in Japan. [41]

Related Research Articles

Ape superfamily of apes

Apes (Hominoidea) are a branch of Old World tailless simians native to Africa and Southeast Asia. They are the sister group of the Old World monkeys, together forming the catarrhine clade. They are distinguished from other primates by a wider degree of freedom of motion at the shoulder joint as evolved by the influence of brachiation. In traditional and non-scientific use, the term "ape" excludes humans, and can include tailless primates taxonomically considered monkeys, and is thus not equivalent to the scientific taxon Hominoidea. There are two extant branches of the superfamily Hominoidea: the gibbons, or lesser apes; and the hominids, or great apes.

Catarrhini Parvorder of Old World monkeys and apes

The Catarrhini, catarrhine monkeys or Old World anthropoids are the sister group to the New World monkeys, the Platyrrhini. The Platyrrhini emerged within "monkeys" by migration to South America from Afro-Arabia, likely by ocean. With respect to the ones that stayed behind, Geoffroy in 1812 grouped the apes (Hominoidea) and the Cercopithecoidea together and established the name Catarrhini, "Old World monkeys",. Darwin in the late 19th century imagined correctly that apes were the sister to the Cercopithecoidea. There has been some resistance to directly designate apes as monkeys despite the scientific evidence, so "Old World monkey" may be taken to mean the Cercopithecoidea or the Catarrhini. That apes are monkeys was already realized by Georges-Louis Leclerc, Comte de Buffon in the 18th century. The apes are further divided into the lesser apes or gibbons and the great apes, consisting of the orangutans, gorillas, chimpanzees and humans. The Catarrhini are all native to Africa and Asia. Members of this parvorder are called catarrhines.

Siamang the fourth largest living species of ape in the world after the orangutans

The siamang is an arboreal black-furred gibbon native to the forests of Indonesia, Malaysia and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching 1 m in height, and weighing up to 14 kg. The siamang is the only species in the genus Symphalangus.

Lar gibbon species of mammal

The lar gibbon, also known as the white-handed gibbon, is an endangered primate in the gibbon family, Hylobatidae. It is one of the better-known gibbons and is often kept in captivity.

Hoolock gibbon genus of mammals

The hoolock gibbons are three primate species of genus Hoolock in the gibbon family, Hylobatidae, native to eastern Bangladesh, Northeast India, Myanmar and Southwest China.

Klosss gibbon Primate in the gibbon family, endemic to the Mentawai Islands

Kloss's gibbon, also known as the Mentawai gibbon or the bilou, is an endangered primate in the gibbon family, Hylobatidae. It is identifiable in that it is all black, resembling the siamang with its black fur, but is considerably smaller and lacks the siamang's distinctive throat pouch. Kloss's gibbon reaches a size 44 to 63 cm and weigh at most 6 kg. As is the case for all gibbons, they have long arms and no tail.

<i>Hylobates</i> genus of mammals

The genus Hylobates is one of the four genera of gibbons. Its name means "forest walker", from the Greek hūlē and bates.

<i>Nomascus</i> genus of mammals

Nomascus is the second-most speciose genus of gibbons. Originally, this genus was a subgenus of Hylobates, and all individuals were considered one species, Hylobates concolor. Species within Nomascus are characterized by 52 chromosomes. Some species are all black, some are light with a distinct black tuft of crown fur, and some have distinct, light-colored cheek patches. Nomascus is found from southern China (Yunnan) to southern Vietnam, and also on Hainan Island. One species, Nomascus nasutus, has been deemed "the most critically endangered ape species in the world". All species in this genus are either endangered or critically endangered.

Black crested gibbon species of mammal

The black crested gibbon is an endangered species of gibbon found in China, Laos, and northern Vietnam, with four subspecies.

Eastern black crested gibbon species of mammal

The eastern black crested gibbon, also known as the Cao-vit black crested gibbon or the Cao-vit crested gibbon, is a species of gibbon from southeast China and northern Vietnam.

Northern white-cheeked gibbon species of mammal

The northern white-cheeked gibbon is a species of gibbon native to South East Asia. It is closely related to the southern white-cheeked gibbon, with which it was previously considered conspecific. The females of the two species are virtually indistinguishable in appearance.

Eastern hoolock gibbon species of mammal

The eastern hoolock gibbon is a primate from the gibbon family, Hylobatidae. It is one of three species of hoolock gibbon. This species is found in extreme eastern corner of Assam and parts of Arunachal Pradesh, Myanmar east of the Chindwin River, such as the Mahamyaing Wildlife Sanctuary, and in south west Yunnan of China. The other hoolock gibbon, the western hoolock, occurs farther to the west. Indian records for the eastern species may actually represent the western hoolock.

Western hoolock gibbon species of mammal

The western hoolock gibbon is a primate from the gibbon family, Hylobatidae. The species is found in Assam, Mizoram & Meghalaya in India, Bangladesh and in Myanmar west of the Chindwin River.

Hainan black crested gibbon species of mammal

The Hainan black-crested gibbon or Hainan gibbon, is a species of gibbon found only on Hainan Island, China. It was formerly considered a subspecies of the eastern black crested gibbon from Hòa Bình and Cao Bằng provinces of Vietnam and Jingxi County in Guangxi Zhuang Autonomous Region, China. Molecular data, together with morphology and call differences, suggest it is a separate species. Its habitat consists of broad-leaved forests and semi-deciduous monsoon forests. It feeds on ripe, sugar-rich fruit, such as figs and, at times, leaves, and insects.

<i>Ficus neriifolia</i> species of plant

Ficus neriifolia is a species of fig (Ficus). It is native to Asia, including Bhutan, Burma, China, India, and Nepal.

Southern white-cheeked gibbon species of mammal

The southern white-cheeked gibbon is a species of gibbon native to Vietnam and Laos. It is closely related to the northern white-cheeked gibbon and the yellow-cheeked gibbon ; it has previously been identified as a subspecies of each of these.

The Sumatran lar gibbon, also known as the Sumatran white-handed gibbon, is a subspecies of the lar gibbon, a primate in the gibbon family Hylobatidae. It is native to the island of Sumatra, Indonesia. It shares the tree tops with orangutans, which, like the gibbon, rarely come out of the trees due to predators, such as tigers and possibly sun bears.

The Yunnan lar gibbon, also known as the Yunnan white-handed gibbon, is a subspecies of the lar gibbon, a primate in the gibbon family, Hylobatidae. This Chinese subspecies is thought to be extinct.

Gibbon–human last common ancestor Gibbon–human last common ancestor

The phylogenetic split of the superfamily Hominoidea (apes) into the Hylobatidae (gibbons) and Hominidae families is dated to the early Miocene, roughly 20 to 16 million years ago.

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