Tupaia (mammal)

Tupaia is a treeshrew genus in the family Tupaiidae that was first described by Thomas Stamford Raffles in 1821.^[1][2] The name of this genus derives from the Malay word tupai meaning squirrel or small animal resembling a squirrel.^[3]

Tupaia
Pygmy treeshrew
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Scandentia
Family:	Tupaiidae
Genus:	Tupaia Raffles, 1821
Type species
Tupaia ferruginea [1] Raffles, 1821
Species
See text.
Synonyms
Chladobates Schinz, 1824 Cladobates F. Cuvier, 1825 Gladobates Schinz, 1824 Glipora Jentink, 1888 Glirisorex Scudder, 1882 Glisorex Desmarest, 1822 Glisosorex Giebel, 1855 Hylogale Temminck, 1827 Hylogalea Schlegel and Mueller, 1843 Lyonogale Conisbee, 1953 Palaeotupaia Chopra and Vasishat, 1979 Sorex-glis É. Geoffroy and F. Cuvier, 1822 Tana Lyon, 1913 Tapaia Gray, 1860 Tupaja Haeckel, 1866 Tupaya É. Geoffroy and F. Cuvier, 1822

Characteristics

Raffles described the genus as having an elongated snout, eight to 10 incisors, well-developed limbs, five-toed naked feet, and the sole furnished with projecting pads and sharp claws, with a habit and tail of a squirrel.^[2]

Marcus Ward Lyon published a revision of the genus in 1913, and also noted the squirrel-like appearance of Tupaia species, which only lack the long black whiskers and have smaller ears. They do not have any markings on the face, the naked area of the nose is finely reticulated, an oblique stripe on the shoulder is more or less distinct, and the tail is haired but not tufted. The braincase is about as wide as the maxillary tooth row is long. The temporal fossa is smaller than the orbit. The dental formula is 2.1.3.33.1.3.3. The first pair of upper incisors is longer than the second, while the second pair of lower incisors is slightly larger than the first and third pairs. The lower canines are better developed than the upper ones and stand high above the adjacent premolars. The size of head, body, and tail varies between species.^[4]

One outstanding characteristic of Tupaia species is their color vision. They have rod and cone visual receptors similar to humans and other primates.^[5]

Classification and taxonomic history

See also: List of scandentians

When Diard and Duvaucel described the first specimen of the common treeshrew Tupaia glis in 1820, they considered it a species of Sorex.^[6] T. everetti was moved back into the genus from Urogale, disbanding the latter, based on a 2011 molecular phylogeny.^[7]

The following species are in the genus Tupaia:^[1]

• Northern treeshrew T. belangeri — (Wagner, 1841)^[8]
• Golden-bellied treeshrew T. chrysogaster — G. S. Miller, 1903^[9]
• Bangka Island treeshrew T. dicolor — Lyon, 1906^[10]
• Striped treeshrew T. dorsalis — Schlegel, 1857^[11]
• Mindanao treeshrew T. everetti — Thomas, 1892^[12]
• Sumatran treeshrew T. ferruginea — Raffles 1821^[13]
• Common treeshrew T. glis — Diard & Duvaucel, 1820^[6]
• Slender treeshrew T. gracilis — Thomas, 1893^[14]
• Javan treeshrew T. hypochrysa — Thomas, 1895^[15]
• Horsfield's treeshrew T. javanica — Horsfield, 1821^[4][16]
• Long-footed treeshrew T. longipes — Thomas, 1893^[17]
• Pygmy treeshrew T. minor — Günther, 1876^[18]
• Mountain treeshrew T. montana — Thomas, 1892^[12]
• Nicobar treeshrew T. nicobarica — (Zelebor, 1868)^[19]
• Palawan treeshrew T. palawanensis — Thomas, 1894^[20]
• Painted treeshrew T. picta — Thomas, 1892^[12]
• Kalimantan treeshrew T. salatana — Lyon, 1895^[21]
• Ruddy treeshrew T. splendidula — J. E. Gray, 1865^[22]
• Large treeshrew T. tana — by Thomas Stamford Raffles, 1821^[2]
• †Tupaia miocenica — Mein & Ginsburg, 1997^[23]

In the past, various authors proposed to place treeshrews in the ordinal rank Insectivora, or considered them close relatives of primates. Since 1972, the treeshrew families Tupaiidae and Ptilocercidae are grouped in the order Scandentia.^[24][25][26]

Distribution and habitat

Tupaia species range from northeastern India, Myanmar, Nicobar Islands eastward to some of the Philippine Islands, and from central China south to Java, Borneo and Sumatra, including islands on the southwest coast. They do not occur on Celebes, nor on islands to the east of Java, with the possible exception of Bali.^[4]

They inhabit the dense undergrowth of tropical forests. With the exception of T. minor, they are primarily terrestrial and forage on the forest floor, usually below 1.5 m (4 ft 11 in). Since they are rarely seen crossing wide roads, populations likely are negatively affected by fragmentation of forests caused by logging operations.^[27]

Ecology and behaviour

Early naturalists described wild-caught captive Tupaia specimens as restless, nervous, and rapidly reacting to sounds and movements.^[4] Their auditory sensitivity is highly developed as the broad frequency range of their hearing reaches far into the ultrasonic.^[28]

The shape of the cheek-teeth of Tupaia species indicate they are foremost insectivores. Captive specimens were reported to hunt ants, flies, crickets, grasshoppers, cockroaches, and small beetles. They hold their food between their forelegs while sitting on their haunches. After feeding, they smooth their heads and faces with both forepaws, and lick their lips and palms. They are also fond of water, both to drink and to bathe.^[4] They fortify their diet with soft fruits that are mostly dispersed by birds. They swallow the pulp, but reject fibrous components, which they cannot digest due to their long and small intestines and rudimentary ceca.^[29]

The well-developed olfactory perception of treeshrews enables them to easily detect food among the leaf litter on the forest floor. Their sensitivity for odours coupled with scent-marking of their territories is important in their interaction with conspecifics.^[30][31]

Observations of Tupaia species in their natural habitats suggest they usually form monogamous pairs. Social behaviour differs between species and the available food resources in their territories. Where food is adequate and sufficient, they tolerate conspecifics without engaging in territorial disputes.^[27] Common treeshrews observed in the Bukit Timah Nature Reserve defended diminishing food resources by chasing away residents of adjacent areas.^[31]

Birds of prey, snakes, and small carnivores are known to hunt treeshrews. Humans have no interest in killing them for food because of their unpleasant taste, and they are rarely seen as pests.^[32]

Reproduction and development

Treeshrews share more similarity with rodents and squirrels than with primates in regards to their reproduction and development. In contrast to primates, which produce one baby with longer gestation periods, treeshrews generally have litters of two or three young and are only in utero about 45 days. Female treeshrews give birth in nests made of many dry leaves, and are known to leave the young unattended while returning occasionally to give them milk. Parental care of Tupaia is relatively limited.^[33]

The young remain in the nest for 33 days on average, developing gradually before they exit the nest. Ten identified embryonic developmental stages are seen in Tupaia species.^[34] Baby treeshrews are sexually immature until about 90 days after birth.^[25]

Medical research

Their close relationship to primates makes treeshrews important model organisms in human medical research. A study investigating the effects of the Borna disease virus on treeshrews has given new insight into neurological disease.^[35]

Since Tupaia species share so many similarities with primates, yet are more abundant and have more plentiful progeny than them, interest is increasing in using them as an alternative model for use in human medical research. Successful psychosocial studies were carried out, and dramatic behavioral, neuroendocrinal, and physiological changes occurred in subordinate males of Tupaia, similar to depressed human patients. Their susceptibility to viruses has also piqued interest in using them to study immune responses to infections such as hepatitis B.^[36] Tupaia species have been used to overcome the limitations of using rodent models in the study of human biology and disease mechanisms, as well as the development of new drugs and diagnostic tools. Recent studies have used treeshrews to study infectious, metabolic, neurological, and psychiatric diseases, as well as cancers.^[37]

In 2013, the Virology Journal published an article that documents the use of the northern treeshrew (T. belangeri) as medical models for the H1N1 influenza virus. This was advantageous because other possible candidates such as guinea pigs, rats, mice, and other rodents leave gaps in the information, especially regarding clinical symptoms and transmission. Tupaia, though, displays moderate systemic and respiratory symptoms, as well as pathological changes in the respiratory tract, supporting its use as a beneficial model in H1N1 research.^[38]

References

1. Helgen, K.M. (2005). "Tupaia". In Wilson, D.E.; Reeder, D.M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 104. ISBN 978-0-8018-8221-0. OCLC 62265494.
2. Raffles, T. S. (1821). "Descriptive Catalogue of a Zoological Collection made on account of the Honourable East India Company, in the Island of Sumatra and its Vicinity, under the Direction of Sir Thomas Stamford Raffles, Lieutenant-Governor of Fort Marlborough; with additional Notices illustrative of the Natural History of those Countries". The Transactions of the Linnean Society of London. XIII. Linnean Society of London: 239–340.
3. Wilkinson, R. J. (1901). A Malay-English dictionary Kelly & Walsh Limited, Hongkong, Shanghai and Yokohama.
4. Lyon, M. W., Jr. (1913). Tree shrews: An account of the mammalian family Tupaiidae. Proceedings of the United States National Museum, 45:1–188.
5. Shriver, J .G., Noback, C. R. (1967). Color Vision in the Tree Shrew (Tupaia glis). Folia Primatologia 6: 161−169.
6. Diard, P.M., Duvaucel, A. (1820). "Sur une nouvelle espèce de Sorex — Sorex Glis". Asiatick researches, or, Transactions of the society instituted in Bengal, for inquiring into the history and antiquities, the arts, sciences, and literature of Asia, Volume 14: 470–475.
7. Roberts, T.E.; Lanier, H.C.; Sargis, E.J.; Olson, L.E. (2011). "Molecular phylogeny of treeshrews (Mammalia: Scandentia) and the timescale of diversification in Southeast Asia". Molecular Phylogenetics and Evolution. 60 (3): 358–372. doi:10.1016/j.ympev.2011.04.021. PMID 21565274.
8. Wagner, J. A. (1841). Das peguanische Spitzhörnchen. In: Die Säugethiere in Abbildungen nach der Natur mit Beschreibungen. Supplementband 2. Erlangen: Expedition des Schreber'schen Säugethier- und des Esper'schen Schmetterlingswerkes. Pp. 42–43.
9. Miller, G. S. Jr. (1903). Seventy New Malayan Mammals. Smithsonian Miscellaneous Collections 45: 1–73.
10. Lyon Jr, M. W. (1906). "Mammals of Banka, Mendanau, and Billiton Islands, between Sumatra and Borneo". Proceedings of the United States National Museum. 1906.
11. Schlegel, H. (1857). Tana dorsalis. In: Handleiding Tot de Beoefening der Dierkunde, Ie Deel. Boekdrukkerij van Nys, Breda. Page 59.
12. Thomas, Oldfield (1892). "On some new mammalia from the East-Indian Archipelago". Annals and Magazine of Natural History. 6 (9): 250–254. doi:10.1080/00222939208677313. ISSN 0374-5481.
13. Raffles, T. S. (1821). "XVII. Descriptive Catalogue of a Zoological Collection, Made on Account of the Honourable East India Company, in the Island of Sumatra and Its Vicinity, under the Direction of Sir Thomas Stamford Raffles, Lieutenant-Governor of Fort Marlborough; with Additional Notices Illustrative of the Natural History of Those Countries". Transactions of the Linnean Society of London. 1: 239–274.
14. Thomas, O. (1893). Description of a new Bornean Tupaia. The Annals and Magazine of Natural History 6 (12): 53–54.
15. Thomas, O. (1895). "On some mammals collected by Dr. E. Modigliani in Sipora, Mentawei Islands". Annali del Museo Civico di Storia Naturale Genova. Series 2. 14: 661–672.
16. Horsfield, T. (1824). Zoological researches in Java, and the neighbouring islands. London: Kingsbury, Parbury, & Allen.
17. Thomas, O. (1893). On some new Bornean Mammalia. The Annals and Magazine of Natural History, 6 (11): 341–347.
18. Günther, A. G. (1876). Remarks on some Indian and, more especially, Bornean Mammals. Proceedings of the general meetings for scientific business of the Zoological Society of London: 424–428.
19. Zelebor, J. (1868). Cladobates Nicobaricus. In: Reise der österreichischen Fregatte Novara um die Erde. Zoologischer Theil, Band 1 Säugethiere. Wien: Kaiserliche Akademie der Wissenschaften. Pp. 17–19.
20. Thomas, O. (1894). On the Palawan Representative of Tupaia ferruginea. The Annals and Magazine of Natural History 6 (13): 367.
21. Lyon, M. W. (1913). Treeshrews: an account of the mammalian family Tupaiidae. Vol. 45. US Government Printing Office.
22. Gray, J. E. (1865). Notice of a Species of Tupaia from Borneo, in the Collection of the British Museum. Proceedings of the general meetings for scientific business of the Zoological Society of London: 322.
23. Mein, P. and Ginsburg, L. (1997). Les mammifères du gisement miocène inférieur de Li Mae Long, Thaïlande : systématique, biostratigraphie et paléoenvironnement Geodiversitas 19(4): 783–844|date=4 March 2024
24. Butler, P. M. (1972). The problem of insectivore classification. In: K. A. Joysey and T. S. Kemp (eds.) Studies in vertebrate evolution. Oliver and Boyd, Edinburgh. Pp. 253−265.
25. Martin, R. D. (1968). Reproduction and Ontogeny in tree-shrews (Tupaia belangeri), with reference to their general behaviour and taxonomic relationships. Zeitschrift für Tierpsychologie 25(4): 409–495.
26. McKenna, M. C., Bell, S. K. (1997). Classification of mammals above the species level. Columbia University Press, New York.
27. Emmons, L. (2000). Tupai: A field study of Bornean treeshrews. Berkeley and Los Angeles: University of California Press.
28. Peterson, E. A., Wruble, S. D., Ponzoli, V. I. (1968). Auditory responses in tree shrews and primates. Journal of Auditory Research 8(3): 345–355.
29. Emmons, L. H. (1991). Frugivory in Treeshrews (Tupaia). The American Naturalist. 138(3): 642–649.
30. Gould, E. (1978). The behavior of the moonrat, Echinosorex gymnurus (Erinaceidae) and the pentail shrew, Ptilocercus lowi (Tupaiidae) with comments on the behavior of other insectivora. Zeitschrift für Tierpsychologie 48(1): 1–27.
31. Kawamichi, T. and Kawamichi, M. (1979). Spatial Organization and Territory of Tree Shrews (Tupaia glis). Animal Behavior 27(2): 381–393.
32. Cisneros, L. (2005). "Tupaia glis" (On-line), Animal Diversity Web.
33. Collins, P. M. and Tsang, W. N. (1987). Growth and reproductive development in the male treeshrew (Tupaia belangeri) from birth to sexual maturity. Biology of reproduction 37(2): 261–267.
34. Kuhn, H, and Schwaier, A. (1973). Implantation, early placentation, and the chronology of embryogenesis in Tupaia belangeri. Zeitschrift für Anatomie und Entwicklungsgeschichte 142(3): 315–340.
35. Sprankel, H., Richarz, K., Ludwig, H. and Rott, R. (1978). Behavior Alterations in Tree Shrews Induced by Borna Disease Virus. Medical Microbiology and Immunology 165(1): 1–18.
36. Cao, J., Yang, E. B., Su, J. J., Li, Y., Chow, P. (2003). The Tree Shrew: Adjuncts and Alternatives to Primates as Models for Biomedical Research. Journal of Medical Primatology. 32(3): 123–130.
37. Xu, L., Zhang, Y., Liang, B., Lü, L. B., Chen, C. S., Chen, Y. B., Yao, Y. G. (2013). Tree shrews under the spot light: emerging model of human diseases. Dongwuxue Yanjiu 34(2): 59–69. (in Chinese)
38. Yang, Z. F., Zhao, J., Zhu, Y. T., Wang, Y. T., Liu, R., Zhao, S. S., Li, R. F., Yang, C., Li, J., Zhong, N. S. (2013). The tree shrew provides a useful alternative model for the study of influenza H1N1 virus. Virology Journal 10 (1): 111.