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The common marmoset (Callithrix jacchus), also called white-tufted marmoset or white-tufted-ear marmoset, is a New World monkey. It originally lived on the northeastern coast of Brazil, in the states of Piauí, Paraíba, Ceará, Rio Grande do Norte, Pernambuco, Alagoas, and Bahia.<ref>Template:Cite book</ref> Through release (both intentional and unintentional) of captive individuals, it has expanded its range since the 1920s to Southeast Brazil (its first sighting in the wild for Rio de Janeiro was in 1929), where it became an invasive species, raising concerns about genetic pollution of similar species, such as the buffy-tufted marmoset (Callithrix aurita), and predation upon bird nestlings and eggs.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The whole genome sequence of a female common marmoset was published on 20 July 2014.<ref name=genome>Template:Cite journal</ref> It became the first New World monkey to have its genome sequenced.<ref name=baylor>Template:Cite news</ref>
Physical description and morphologyEdit
Common marmosets are very small monkeys with relatively long tails. Males are slightly larger than females; males have an average height of Template:Convert and females have an average height of Template:Convert. Males weigh Template:Convert on average and females weigh Template:Convert on average.<ref name= "Rowe 1996">Template:Cite book</ref> The pelage of the marmoset is multicolored, being sprinkled with brown, grey, and yellow. It also has white ear tufts and the tail is banded. Its face has black across the nose-area skin and a white blaze on the forehead.<ref>Groves C. (2001) Primate taxonomy. Washington DC: Smithsonian Inst Pr.</ref> The coats of infants are brown and yellow with the ear tuft developing later.
As with other members of the genus Callithrix, the common marmosets have claw-like nails known as tegulae on most of their fingers. Only their halluces (big toes) have the flat nails or ungulae that most other primates have.<ref>Garber PA, Rosenberger AL, Norconk MA. (1996) "Marmoset misconceptions". In: Norconk MA, Rosenberger AL, Garber PA, editors. Adaptive radiations of neotropical primates. New York: Plenum Pr. pp. 87–95.</ref> Marmosets have an arboreal locomotion similar to squirrels. They can hang onto trees vertically and leap between them, and run across branches quadrupedally.<ref name= "Rowe 1996"/><ref name= "Kinzey 1997">Kinzey WG. 1997. "Synopsis of New World primates (16 genera) ". In: Kinzey WG, editor. New world primates: ecology, evolution, and behavior. New York: Aldine de Gruyter. pp. 169–324.</ref> Tegulae are an adaptation for this type of locomotion. Other Callithrix traits shared include enlarged, chisel-shaped incisors and ceca specialized for their diet.<ref name= "Rowe 1996"/>
Range and ecologyEdit
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Common marmosets are native only to east-central Brazil. They have been introduced into other areas and live within the cities of Rio de Janeiro and Buenos Aires, Argentina.<ref>Rylands AB, Coimbra-Filho AF, Mittermeier RA. 1993. "Systematics, geographic distribution, and some notes on the conservation status of the Callitrichidae". In: Rylands AB, editor. Marmosets and tamarins: systematics, behaviour, and ecology. Oxford (England): Oxford Univ Pr. pp. 11–77.</ref> Marmosets can be found in a number of forest habitats. They live in Atlantic coastal forests as well as semideciduous forests farther inland. They can also inhabit savanna forests and riverine forests.<ref name= "Rylands 1993">Rylands AB, de Faria DS. (1993) "Habitats, feeding ecology, and home range size in the genus Callithrix". In: 'Rylands AB, editor. Marmosets and tamarins: systematics, behaviour, and ecology. Oxford (England): Oxford Univ Pr. pp. 262–72.</ref> Marmosets are successful in dry secondary forests and edge habitats.<ref name= "Kinzey 1997"/>
DietEdit
The common marmoset's claw-like nails, incisor shape, and gut specialization reflect their unique diet, which is primarily made of plant exudates and insects. Common marmosets feed on gum, sap, latex, and resin.<ref name= "Kinzey 1997"/><ref name= "Rylands 1993"/> They use their nails to cling to the side of a tree, and with their long lower incisors, chew a hole in the tree.<ref name= "Ferrari 1989">Template:Cite journal</ref> The marmoset then licks up the exudates or swoops them with the teeth.<ref name= "Stevenson 1988">Stevenson MF, Rylands AB. (1988) "The marmosets, genus Callithrix". In: Mittermeier RA, Rylands AB, Coimbra-Filho AF, da Fonseca GAB, editors. Ecology and behavior of neotropical primates, Volume 2. Washington DC: World Wildlife Fund. pp. 131–222.</ref> From 20 to 70% of the marmoset's feeding behavior includes eating exudates.<ref name= "Rowe 1996"/><ref name= "Ferrari 1989"/>
Exudates provide marmosets with a reliable food source in their seasonal habitat. They rely on these foods particularly between January and April, when fruit is not abundant. A marmoset may visit a tree hole multiple times, including those made by other animals. In addition to exudates, insects also prove an important food source for marmosets, making up 24-30% of their food. The small size of marmosets allows them to stalk and ambush them.<ref name= "Rylands 1993"/> Marmosets also eat fruits, seeds, flowers, fungi, nectar, snails, lizards, tree frogs, bird eggs, nestlings, and infant mammals.<ref name= "Stevenson 1988"/> Marmosets may compete for fruit with birds, such as parrots and toucans, and with woolly opossums.<ref name= "Stevenson 1988"/>
BehaviorEdit
Social organizationEdit
Common marmosets live in stable extended families, with only a few members allowed to breed.<ref name= "Digby 1995">Template:Cite journal</ref><ref name= "Ferrari 1996">Template:Cite journal</ref> A marmoset group can contain as many as 15 members, but a more typical number is nine.<ref name= "Stevenson 1988"/> A marmoset family usually contains one or two breeding females, a breeding male, their offspring, and their adult relatives, be they their parents or siblings.<ref name= "Ferrari 1996"/> The females in a group tend to be closely related, and males less so. Males do not mate with breeding females to which they are related. Marmosets may leave their natal groups when they become adults, in contrast to other primate species, which leave at adolescence. Not much is known of the reasons marmosets leave their natal groups.<ref name= "Ferrari 1996"/> Family groups fuse into new groups when a breeding male dies.<ref name= "Lazaro 2001">Template:Cite journal</ref> Within the family groups, the breeding individuals tend to be more dominant. The breeding male and female tend to share dominance. Between two breeding females, though, one is more dominant. In addition, the subordinate female is usually the daughter of the dominant one. For the other members, social rank is based on age.<ref name="Digby 1995"/> Dominance is maintained though various behaviors, postures, and vocalizations, and subordinates groom their superiors.<ref name= "Digby 1995"/>
Reproduction and parentingEdit
Common marmosets have a complex mating system. They were thought to be monogamous, but both polygamy and polyandry have been observed.<ref name= "Digby 1995"/> Nevertheless, most matings are monogamous. Even in groups with two breeding females, the subordinate female often mates with males from other groups. Subordinate females usually do not give birth to fit offspring.<ref name= "Arruda 2005">Template:Cite journal</ref> Mating with extra-group males may allow the female to find potential mates in the future. Females that mate successfully but lose their young move to other groups and may gain dominant breeding positions.<ref name= "Arruda 2005"/>
The breeding individuals in a group need the other members to help raise their young. Thus, the pair behaviorally and physiologically suppresses the reproduction of the other members of the group.<ref>Template:Cite journal</ref><ref name= "Saltzman 1997"/> Since these suppressed individuals are likely related to the breeding pair, they have an incentive to care for the young, as they share genes with them.<ref name= "Saltzman 1997">Template:Cite journal</ref> In addition, the presence of a related male affects female ovulation. Female ovulation does not occur when their fathers are around, but does occur when an unrelated male is nearby, instead. They also display aggressive behavior towards their mothers,<ref name= "Saltzman 1997"/> possibly to displace them.
When conditions are right for them to breed, adult females breed regularly for the rest of their lives. Females flick their tongues at males to solicit mating. The gestation period lasts for 5 months, and females are ready to breed again around 10 days after giving birth. Five months pass between each parturition, so they can give birth twice a year.<ref name= "Stevenson 1988"/> Marmosets commonly give birth to nonidentical twins. Because of this, females are under stress during pregnancy and lactation, and need help from the other members of the family.<ref name= "Kinzey 1997"/><ref name= "Stevenson 1988"/> Infant marmosets instinctively cling to their mother's back and do not voluntarily let go for the first two weeks. After that, they become very active and explore their environment.<ref name= "Stevenson 1988"/> The breeding male (likely the father) begins handling the twins, and all members of the family care for them.<ref name= "Yamamoto 1993">Yamamoto ME. (1993) From dependence to sexual maturity: the behavioural ontogeny of Callitrichidae". In: Rylands AB, editor. Marmosets and tamarins: systematics, behaviour, and ecology. Oxford (England): Oxford Univ Pr. pp. 235–54.</ref> In the following weeks, the young spend less time on their mother's back and more time moving around and playing.<ref name= "Stevenson 1988"/> Infants are weaned at 3 months. At 5 months, they enter their juvenile stage, when they have more interactions with family members other than their parents, and rough play helps to establish their future status. Another set of infants may be born and the previous young carry and play with them.<ref name= "Yamamoto 1993"/> Marmosets become subadults between 9 and 14 months old, act like adults, and go through puberty. At 15 months, they reach adult size and are sexually mature, but cannot breed until they are dominant.<ref name= "Yamamoto 1993"/>
CommunicationEdit
Common marmosets employ a number of vocal and visual communications. To signal alarm, aggression, and submission, marmosets use the "partially open mouth stare", "frown", and "slit-stare", respectively. To display fear or submission, marmosets flatten their ear tufts close to their heads.<ref name= "Stevenson 1988"/> Marmosets have two alarm calls - a series of repeating calls that get higher with each call, known as "staccatos", and short, trickling calls given either intermittently or repeatedly, called "tsiks". Marmoset alarm calls tend to be short and high-pitched.<ref name= "Lazaro 2001"/> Marmosets monitor and locate group members with vibrato-like, low-pitched, generic calls called "trills".<ref name="Jones 1997">Jones CB. (1997) "Quantitative analysis of marmoset vocal communication". In: Pryce C, Scott L, Schnell C, editors. Marmosets and tamarins in biological and biomedical research: proceedings of a workshop. Salisbury (UK): DSSD Imagery. pp. 145–51.</ref> Marmosets also employ "phees", which are whistle-like, generic calls. These serve to attract mates, keep groups together, defend territories, and locate missing group members. Marmosets were recently found to encode the identity of the receiver in their phee calls<ref>Template:Cite journal</ref> — a behavior similar to the human use of names, and one that has been observed in only a few species: humans, dolphins, and African elephants. Marmosets use scent glands on their chests and anogenital regions to mark objects. These are meant to communicate social and reproductive status.<ref name= "Stevenson 1988"/>
StatusEdit
The common marmoset remains an abundant species and is not currently threatened, but its habitat had been degraded at a fast rate, with around 67% of the Cerrado region cleared for human use in the 1990s and around 80% cleared for cultivation more recently.<ref>Cavalcanti RB, Joly CA. (2002) "Biodiversity and conservation priorities in the cerrado region". In: Oliveira PS, Marquis RJ, editors. The cerrados of Brazil: ecology and natural history of a neotropical savanna. New York: Columbia Univ Pr. pp. 351–67.</ref> In addition, marmosets are captured and traded as pets. Though popular as pets, they become difficult to control as they get older and may be abandoned or killed.<ref>Template:Cite journal</ref> Common marmosets have also been used for medical experiments. They are used as such in Europe more so than in the United States, and are the most common nonhuman primates to be experimented on.<ref name= "Abbott 2003">Template:Cite journal</ref> They are used as model organisms in areas of research such as teratology, periodontal disease, reproduction, immunology, endocrinology, obesity, and aging.<ref name= "Abbott 2003"/><ref>Rylands AB. (1997) "The callitrichidae: a biological overview". In: Pryce C, Scott L, Schnell C, editors. Marmosets and tamarins in biological and biomedical research: proceedings of a workshop. Salisbury (UK): DSSD Imagery. pp. 1–22.</ref>
GenomeEdit
In 2014, a female became the first nonhuman primate, among the New World monkeys, to have its complete genome sequenced.<ref name=baylor/> The genome size is 2.26 Gbp, and contains 21,168 genes.<ref name=genome/> Segmental duplications added a total of 138 Mb of nonredundant sequences (4.7% of the whole genome), slightly fewer than observed in humans<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> or chimpanzees (about 5%),<ref>Template:Cite journal</ref> but more than in orangutans (3.8%).<ref>Template:Cite journal</ref>
ReferencesEdit
External linksEdit
- Common Marmoset Care
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- View the Marmoset genome in Ensembl.
- Template:UCSC genomes