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Behavior

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Perception Channels: tactile ; chemical

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Ciszek, D. and P. Myers 2000. "Tenrecidae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Tenrecidae.html
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Deborah Ciszek, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Morphology

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Other Physical Features: endothermic ; bilateral symmetry

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Ciszek, D. and P. Myers 2000. "Tenrecidae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Tenrecidae.html
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Reproduction

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Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual

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Ciszek, D. and P. Myers 2000. "Tenrecidae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Tenrecidae.html
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Deborah Ciszek, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tenrecs (Family Tenrecidae)

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Tenrrecs are widely diverse, due to convergent evolution; various species resemble hedgehogs, shrews, opossums, mice and otters, but are not closely related to any of these groups. Their closest living relatives are African, insectivorous mammals such as golden moles and elephant shrews, which share a common ancestry with aardvarks, hyraxes, elephants, and sea cows in the group Afrotheria (3-9). All Madagascan species seem to have evolved from a single, common ancestor, with the mainland tenrecs comprising the next, most-closely related mammalian species (11,12). Some fossil specimens from the early Miocene of Kenya show close affinities to living species from Madagascar (13), such as Geogale aurita. The fossil record of tenrecids is relatively poor. The oldest known fossils are from the Miocene in East Africa and the Pleistocene in Madagascar, but the group is certainly considerably older. Recent molecular evidence (Murphy et al. 2001) suggests that they should be removed from the Insectivora and placed within a group of African mammals, the Afrotheria, which includes aardvarks, elephants, hyraxes, sea cows, elephant shrews, and golden moles as well as tenrecs. Tenrecs live in Madagascar and western central Africa and occupy aquatic, arboreal, terrestrial and fossorial environments. Some live in Madagascar's dry deciduous forests, while otter shrews live in fast-running streams of the African tropics. Tenrecs have radiated to include species that resemble, morphologically and ecologically, widely diverse mammals including hedgehogs, shrews, opossums, mice and otters. Tenrecs lack jugals, and their zygomatic arches are incomplete. Their tympanic bones are annular, and the squamosal contributes to the roof of the tympanic cavity. The dental formula varies consirably among species: 2-3/2-3, 1/1, 2-3/2-3, 2-4/2-3 = 32-40. The permanent dentition in tenrecs tends not to completely erupt until well after adult body size is reached (14). This features is shared by elephants, hyraxes, sengis and golden moles (but apparently not aardvarks), consistent with their descent from a common ancestor. The upper molars are zalambdodont, except in the otter shrews (Potamogalinae), where they are dilambdodont. The urogenital and anal apertures are included in a common opening or cloaca, a feature more commonly seen in birds, reptiles, and amphibians. The eyes are small. Many tenrecs do not maintain a constant body temperature, but let their bodies cool down while they are at rest. At least one species hibernates. Male tenrecids do not need a scrotum to cool their sperm as most other mammals do (2), so the testes remain within the body cavity. Most species are nocturnal and have poor eyesight. Their other senses are well developed and they have especially sensitive whiskers. During abnormally hot summer weather, tenrecs enter a state of inactivity, called aestivation and resembling hibernation. Before the start of the Austral winter (May-September), tenrecs eat more and lay down fat reserves in their bodies or tails before hibernating, which they usually do in burrows with the entrance plugged with soil. Madagascan winters are quite mild and could be termed the cool, dry season, but the vegetation and hence the food supplies, suffer from lack of rain and the tenrecs become dormant. Dormant tenrecs dug from their burrows are stiff and cold to the touch, have a very low breathing rate and lack food in the stomach or faeces in the intestine. When active, the body temperature that ranges from 75.2° F (24°C) to 95°F (35°C), much lower than most mammals.The body temperature of hibernating tenrecs is usually just 1.8° F (1°C) above the ambient temperature (17). This behaviour occurs with captive zoo specimens in countries with cooler average temperatures than their tropical Madagascan homeland (16). At least some species of tenrecs are social, living in multigenerational family groups with over 12 individuals. All species seem to be at least somewhat omnivorous, with invertebrates forming most the largest part of their diets. Tenrecs have a gestation period of 50-64 days and give birth to a relatively undeveloped young. Otter shrews have two young per litter, but the tailless tenrec has up to 29 teats and can have 32 young, more than other mammals (2). Some inhabitants of Mauritius eat tenrec meat. Subfamily Geogalinae: Large-eared tenrec (Geogale aurita) Subfamily Oryzorictinae: These small tenrecs lack spines. Most are shrew-like or mole-like, but Limnogale is aquatic. Some are highly fossorial. Web-footed tenrec (Limnogale mergulus); Short-tailed shrew tenrec (Microgale brevicaudata); Cowan's shrew tenrec (M. cowani); Dobson's shrew tenrec (M. dobsoni); Drouhard's shrew tenrec (M. drouhardi); Dryad shrew tenrec (M. dryas); Pale shrew tenrec (M. fotsifotsy); Gracile shrew tenrec (M. gracilis); M. grandidieri; Naked-nosed shrew tenrec (M. gymnorhyncha); Jenkins' shrew tenrec (M. jenkinsae); Northern shrew tenrec (M. jobihely); Lesser long-tailed shrew tenrec (M. longicaudata); M. macpheei (extinct); Major's long-tailed tenrec (M. majori); Montane shrew tenrec (M. monticola); Nasolo's shrew tenrec (M. nasoloi); Pygmy shrew tenrec (M. parvula); Greater long-tailed shrew tenrec (M. principula); Least shrew tenrec (M. pusilla); Shrew-toothed shrew tenrec (M. soricoides); Taiva shrew tenrec (M. taiva); Talazac's shrew tenrec (M. talazaci); Thomas's shrew tenrec (M. thomasi); Mole-like rice tenrec (Oryzorictes hova); Four-toed rice tenrec (O. tetradactylus) Subfamily Potamogalinae: Otter shrews are modified for an aquatic life and probably represent an early branch of the family. Nimba otter shrew (Micropotamogale lamottei); Ruwenzori otter shrew (M. ruwenzorii); Giant otter shrew (Potamogale velox) Subfamily Tenrecinae: These tenrecs are relatively large (up to the size of a cat) and highly variable in body form. All have spines, which are barbed and detachable in some forms and are controlled by a well-developed muscle, the panniculus carnosus. Tenrecines are mostly nocturnal and mostly omnivorous. Lesser hedgehog tenrec (Echinops telfairi); Highland streaked tenrec (Hemicentetes nigriceps); Lowland streaked tenrec (H. semispinosus); Greater hedgehog tenrec (Setifer setosus); Common tenrec (Tenrec ecaudatus)

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Tenrec

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A taxidermy mount of a tenrec in defensive mode, Horniman Museum and Gardens, London

A tenrec (/ˈtɛnrɛk/) is any species of mammal within the afrotherian family Tenrecidae, which is endemic to Madagascar.[2] Tenrecs are a very diverse group; as a result of convergent evolution[3] some resemble hedgehogs, shrews, opossums, rats, and mice. They occupy aquatic, arboreal, terrestrial, and fossorial environments. Some of these species including the greater hedgehog tenrec, can be found in the Madagascar dry deciduous forests. However, the speciation rate in this group has been higher in humid forests.[4]

All tenrecs are believed to descend from a common ancestor that lived 29–37 million years ago[4][5][6] after rafting over from Africa.[7][8] The split from their closest relatives, African otter shrews, is estimated to have occurred about 47–53 million years ago.[4][5][6]

Etymology

The word tenrec is borrowed, via French,[9] from the Malagasy word tandrakacode: mlg promoted to code: mg (variant of trandrakacode: mlg promoted to code: mg [10]), which refers to the tailless tenrec (Tenrec ecaudatus); it has been speculated that the Malagasy word is related to Malay: landak, lit.'porcupine'.[11]

Evolution

Tenrecs are believed to have evolved from a single species that colonized Madagascar between 42 and 25 million years ago. The question of how this family reached Madagascar is still unresolved, but the leading hypothesis suggests a small number of individuals may have found themselves on floating vegetation and crossed the Mozambique Channel, which separates Madagascar from southeastern Africa.[2] The Tenrecidae family is one of only four extant terrestrial mammal lineages to have colonized and diversified on Madagascar.[12]

Once established on Madagascar, tenrecs diversified to occupy various niches on the island. Many evolved resemblances to familiar but unrelated mammals that are not found on Madagascar. For instance, the two species of hedgehog tenrec possess coats of hardened spines and the ability to roll into a ball when threatened, characteristics similar to those of true hedgehogs. This example, along with others, demonstrates convergent evolution; it has provided evolutionary biologists with opportunities to study adaptation over evolutionary timescales.[2]

Characteristics

Tenrecs are small mammals of variable body form. The smallest species are the size of shrews, with a body length of around 4.5 cm (1.8 in), and weighing just 5 g (0.18 oz), while the largest, the common or tailless tenrec, is 25 to 39 cm (9.8 to 15.4 in) in length, and can weigh over 1 kilogram (2.2 lb).[13] Although they may resemble shrews, hedgehogs, or opossums, they are not closely related to any of these groups, their closest relatives being the otter shrews, and after that other African insectivorous mammals including golden moles and elephant shrews. The common ancestry of these animals which is in the group Afrotheria, was not recognized until the late 1990s.[14] Continuing work on the molecular[15][16] and morphological[17][18][19][20] diversity of afrotherian mammals has provided ever increasing support for their common ancestry.

Unusually among placental mammals, the anus and urogenital tracts of tenrecs share a common opening, or cloaca which is a feature more commonly seen in birds, reptiles, and amphibians. They have a low body temperature, sufficiently low enough that they do not require a scrotum to cool their sperm as do most other mammals.[13][21]

All species appear to be at least somewhat omnivorous, with invertebrates forming the largest part of their diets. One species, Microgale mergulus, is semiaquatic (similar to the lifestyle of their closest relatives, the otter shrews).[22] All of the species, semiaquatic or not, appear to have evolved from a single, common ancestor with the otter shrews comprising the next, most-closely related mammalian species.[23][24] While the fossil record of tenrecs is scarce, at least some specimens from the early Miocene of Kenya show close affinities to living species from Madagascar,[25] such as Geogale aurita.

Most species are nocturnal and have poor eyesight. Their other senses are well developed, however and they have especially sensitive whiskers. As with many of their other features, the dental formula of tenrecs varies greatly between species; they can have from 32 to 42 teeth in total. Unusual for mammals, the permanent dentition in tenrecs tends not to completely erupt until well after adult body size has been reached.[26] This is one of several anatomical features shared by elephants, hyraxes, sengis, and golden moles (but apparently not aardvarks), consistent with their descent from a common ancestor.

Tenrecs have a gestation period of 50 to 64 days, and give birth to a number of relatively undeveloped young. While the otter shrews have just two young per litter, the tailless tenrec can have as many as 32, and females possess up to 29 teats, more than any other mammal.[13] Some tenrec species are social, living in multigenerational family groups with over a dozen individuals.

Interaction with humans

In the island nation of Mauritius, and also on the Comoran island of Mayotte some of the inhabitants eat tenrec meat, although it is difficult to obtain (as it is not sold in shops or markets) and difficult to prepare correctly.

The lesser hedgehog tenrec (Echinops telfairi) is one of 16 mammalian species that will have its genome sequenced as part of the Mammalian Genome Project. It is increasingly popular in the pet trade, and in the future may serve as an important model organism in biomedicine, as it is only distantly related to the mice, rats, guinea pigs, and rhesus macaques which comprise the most common research animals.

Threats

Of the 31 species assessed, 24 (77%) are categorized by the IUCN Red List as Least Concern, 1 species as Data Deficient, 4 species as Vulnerable, and 2 species as Endangered.[27]

The conservation status of many tenrec species is of concern due to an increase of threats within the last 50 years. The main threats facing tenrecs include habitat loss due to deforestation, fragmentation and degradation, hunting, incidental capture, and climate change. Slash-and-burn agriculture, as well as commercial logging and mining of metals is negatively affecting tenrec species that inhabit forests. Five of the six threatened Tenrec species are dependent on forest habitats.[27]

Conservation

As of 2022, conservation of the tenrec population is not being prioritized. Because most tenrecs are dependent on forest habitats, conservation efforts would need to include a focus on reduction in deforestation on Madagascar as well as habitat restoration.[27] Current conservation efforts include that of the Madagascar Ankizy Fund, started by a paleontological team from Stony Brook University to improve access to health care and education facilities for villagers in remote areas of Madagascar. A healthy and educated local human population will in the long term, benefit the Malagasy fauna, such as tenrecs.[28]

Species

The three subfamilies, eight genera, and 31 extant species of tenrecs are:[29]

FAMILY TENRECIDAE

See also

References

  1. ^ Martin Pickford (2015). "Late Eocene Potamogalidae and Tenrecidae (Mammalia) from the Sperrgebiet, Namibia" (PDF). Communications of the Geological Survey of Namibia. 16: 114–152.
  2. ^ a b c Olson, Link E. (2013). "Tenrecs". Current Biology. 23 (1): R5–R8. doi:10.1016/j.cub.2012.11.015. PMID 23305671.
  3. ^ Olson, Link E (2013). "Tenrecs". Current Biology. 23 (1): R5–R8. doi:10.1016/j.cub.2012.11.015. PMID 23305671.
  4. ^ a b c d e Everson, K. M.; Soarimalala, V.; Goodman, S. M.; Olson, L. E. (2016). "Multiple Loci and Complete Taxonomic Sampling Resolve the Phylogeny and Biogeographic History of Tenrecs (Mammalia: Tenrecidae) and Reveal Higher Speciation Rates in Madagascar's Humid Forests". Systematic Biology. 65 (5): 890–909. doi:10.1093/sysbio/syw034. PMID 27103169.
  5. ^ a b Douady, C. J.; Catzeflis, F.; Kao, D. J.; Springer, M. S.; Stanhope, M. J. (2002). "Molecular Evidence for the Monophyly of Tenrecidae (Mammalia) and the Timing of the Colonization of Madagascar by Malagasy Tenrecs". Molecular Phylogenetics and Evolution. 22 (3): 357–363. doi:10.1006/mpev.2001.1055. PMID 11884160.
  6. ^ a b Poux, C.; Madsen, O.; Glos, J.; de Jong, W. W.; Vences, M. (2008). "Molecular phylogeny and divergence times of Malagasy tenrecs: Influence of data partitioning and taxon sampling on dating analyses". BMC Evolutionary Biology. 8 (1): 102. doi:10.1186/1471-2148-8-102. PMC 2330147. PMID 18377639.
  7. ^ Kinver, M. (2010-01-20). "Mammals 'floated to Madagascar'". BBC News web site. BBC. Retrieved 2010-01-20.
  8. ^ Ali, J. R.; Huber, M. (2010-01-20). "Mammalian biodiversity on Madagascar controlled by ocean currents". Nature. 463 (4 Feb. 2010): 653–656. Bibcode:2010Natur.463..653A. doi:10.1038/nature08706. PMID 20090678. S2CID 4333977.
  9. ^ "tenrec". Merriam-Webster Dictionary. Merriam-Webster. 2021. Retrieved 4 December 2021.{{cite web}}: CS1 maint: url-status (link)
  10. ^ "Rakibolana malagasy sy Rakipahalalana momba an' i Madagasikara : trandraka". mg.mondemalgache.org. Retrieved 2022-06-12.
  11. ^ Blench, Roger; Walsh, Martin (2011), "Faunal names in Malagasy: their etymologies and implications for the prehistory of the East African coast", 11th International Conference on Austronesian Linguistics, Aussois, France, CiteSeerX 10.1.1.467.8453
  12. ^ Everson, Kathryn M.; Soarimalala, Voahangy; Goodman, Steven M.; Olson, Link E. (2016-04-21). "Multiple Loci and Complete Taxonomic Sampling Resolve the Phylogeny and Biogeographic History of Tenrecs (Mammalia: Tenrecidae) and Reveal Higher Speciation Rates in Madagascar's Humid Forests". Systematic Biology. 65 (5): 890–909. doi:10.1093/sysbio/syw034. ISSN 1063-5157. PMID 27103169.
  13. ^ a b c Nicholl, Martin (1984). Macdonald, D. (ed.). The Encyclopedia of Mammals. New York: Facts on File. pp. 744–747. ISBN 978-0-87196-871-5.
  14. ^ Stanhope, MJ; Waddell, VG; Madsen, O; de Jong, W; Hedges, SB; Cleven, GC; Kao, D; Springer, MS (1998). "Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals". PNAS. 95 (17): 9967–9972. Bibcode:1998PNAS...95.9967S. doi:10.1073/pnas.95.17.9967. PMC 21445. PMID 9707584.
  15. ^ Springer MS, Stanhope MJ, Madsen O, de Jong WW (2004). "Molecules consolidate the placental mammal tree". Trends Ecol Evol. 19 (8): 430–438. doi:10.1016/j.tree.2004.05.006. PMID 16701301. S2CID 1508898.
  16. ^ Robinson, T. J. Fu, B. Ferguson-Smith, M. A. Yang, F. (2004). "Cross-species chromosome painting in the golden mole and elephant-shrew: support for the mammalian clades Afrotheria and Afroinsectiphillia but not Afroinsectivora". Proceedings of the Royal Society B. 271 (1547): 1477–1484. doi:10.1098/rspb.2004.2754. PMC 1691750. PMID 15306319.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ^ Asher RJ; Bennet N; Lehmann T. (2009). "The new framework for understanding placental mammal evolution". BioEssays. 31 (8): 853–864. doi:10.1002/bies.200900053. PMID 19582725. S2CID 46339675.
  18. ^ Tabuce, R.; Marivaux, L.; Adaci, M.; Bensalah, M.; Hartenberger, J.-L.; Mahboubi, M.; Mebrouk, F.; Tafforeau, P.; Jaeger, J.-J. (2007). "Early tertiary mammals from North Africa reinforce the molecular Afrotheria clade". Proceedings of the Royal Society B. 274 (1614): 1159–1166. doi:10.1098/rspb.2006.0229. PMC 2189562. PMID 17329227.
  19. ^ Seiffert, E. (2007). "A new estimate of afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence". BMC Evol Biol. 7 (224): 13. doi:10.1186/1471-2148-7-224. PMC 2248600. PMID 17999766.
  20. ^ Sanchez-Villagra, M. R., Narita, Y. and Kuratani, S. (2007). "Thoracolumbar vertebral number: the first skeletal synapomorphy for afrotherian mammals". Syst Biodivers. 5 (1): 1–17. doi:10.1017/S1477200006002258. S2CID 85675984.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ Yin, Steph (29 June 2018). "The Evolutionary Origin of Descending Testicles". The New York Times. Retrieved 2018-07-10.
  22. ^ Benstead, J. P.; L. E. Olson (2003). "Limnogale mergulus, web-footed tenrec or aquatic tenrec". In S. M. Goodman; J. P. Benstead (eds.). The natural history of Madagascar. Chicago: University of Chicago Press. pp. 1267–1273. ISBN 978-0-226-30307-9.
  23. ^ Olson LE, Goodman SM (2003). "Phylogeny and biogeography of tenrecs". In Goodman SM, Benstead JP (eds.). The Natural History of Madagascar. Chicago: Chicago University Press. pp. 1235–1242. ISBN 978-0-226-30307-9.
  24. ^ Poux C; Madsen O; Glos J; de Jong WW; Vences M. (2008). "Molecular phylogeny and divergence times of Malagasy tenrecs: influence of data partitioning and taxon sampling on dating analyses". BMC Evol Biol. 8: 102. doi:10.1186/1471-2148-8-102. PMC 2330147. PMID 18377639.
  25. ^ Asher RJ, Hofreiter M (2006). "Tenrec phylogeny and the noninvasive extraction of nuclear DNA". Syst Biol. 55 (2): 181–194. doi:10.1080/10635150500433649. PMID 16522569.
  26. ^ Asher, R. J.; Lehmann, T. (2008). "Dental eruption in afrotherian mammals". BMC Biol. 6: 14. doi:10.1186/1741-7007-6-14. PMC 2292681. PMID 18366669.
  27. ^ a b c Stephenson, P. J.; Soarimalala, Voahangy; Goodman, Steven M.; Nicoll, Martin E.; Andrianjakarivelo, Vonjy; Everson, Kathryn M.; Hoffmann, Michael; Jenkins, Paulina D.; Olson, Link E.; Raheriarisena, Martin; Rakotondraparany, Felix (Jan 2021). "Review of the status and conservation of tenrecs (Mammalia: Afrotheria: Tenrecidae)". Oryx. 55 (1): 13–22. doi:10.1017/S0030605318001205. ISSN 0030-6053. S2CID 155184737.
  28. ^ "Afrotherian Conservation | IUCN Afrotheria Specialist Group". www.afrotheria.net. Retrieved 2022-04-23.
  29. ^ Bronner, G.N.; Jenkins, P.D. (2005). "Order Afrosoricida". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 72–77. ISBN 978-0-8018-8221-0. OCLC 62265494.

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Tenrec: Brief Summary

provided by wikipedia EN
A taxidermy mount of a tenrec in defensive mode, Horniman Museum and Gardens, London

A tenrec (/ˈtɛnrɛk/) is any species of mammal within the afrotherian family Tenrecidae, which is endemic to Madagascar. Tenrecs are a very diverse group; as a result of convergent evolution some resemble hedgehogs, shrews, opossums, rats, and mice. They occupy aquatic, arboreal, terrestrial, and fossorial environments. Some of these species including the greater hedgehog tenrec, can be found in the Madagascar dry deciduous forests. However, the speciation rate in this group has been higher in humid forests.

All tenrecs are believed to descend from a common ancestor that lived 29–37 million years ago after rafting over from Africa. The split from their closest relatives, African otter shrews, is estimated to have occurred about 47–53 million years ago.

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