| 词条 | Tawny-bellied cotton rat |
| 释义 |
| status = LC | status_system = IUCN3.1 | status_ref = [1] | genus = Sigmodon | species = fulviventer | authority = J.A. Allen, 1889 | synonyms = }} The tawny-bellied cotton rat (Sigmodon fulviventer) is a species of rodent in the family Cricetidae. It is found in Mexico and in the US states of Arizona and New Mexico.[1] DescriptionSexual dimorphism is not present, but the adult male weighs slightly more than the female at {{convert|222|g}} compared to {{convert|206|g}}. The tail has small scales and is covered in hair which distinguishes it from the larger scales of the closely related hispid cotton rat (Sigmodon hispidus).[2] Another characteristic distinguishing it from S. hispidus is a short and broad rather than elongated skull. The dentition is marked by well-developed maxillary incisors and high-crowned molars.[3] The fur is tawny on the belly (the origin of the species' common name), and black and tan speckled on the back. The fur body contains three types of hair: guard-awl hair, guard hair, and under hair. The guard hair is the longest with the guard-awl and under hair following in decreasing length.[2] Whiskers are located on the face and have been observed to play a role in maintaining body position while swimming.[4] Distribution and habitatThe species inhabits the grasslands of central Mexico, expanding north to the central and southwestern parts of New Mexico and southeastern parts of Arizona.[2] It prefers areas with dense grass, in which it makes navigational trails called runways that resemble a tunnel with a grass covering. It feeds on grasses, specifically bunchgrass, which they also use in nest-building.[8] Its range in central New Mexico is expanding westward due to an increase in precipitation and in temperature from climate change.[5] The tawny-bellied cotton rat occurs in the same area as the closely related hispid cotton rat, with the former occupying the moister areas and the latter the more arid areas.[5] When living in adjacent habitats, one species tends to become more numerous while the other maintains a smaller population. Even though both species seem to avoid one another, there is a passive, indirect competition between the species. In Durango, Mexico, S. fulviventer was found to be dominant, probably due to being a specialist compared to the generalist S. hispidus.[6] As a model animalThe tawny-bellied cotton rat is used as a model organism to develop and test human pathogen treatments.[6] It is affected by many of the same viral and bacterial infections that humans are susceptible to, which helps create vaccines and therapeutic treatments. Other factors that make the species a desirable test subject are the existence of inbred strains, ease of handling, and inexpensive upkeep.[7] Some of the diseases tested on the cotton rat are respiratory syncytial virus,[8] and pulmonary tuberculosis,[9] and HIV type-1.[7] In the case of HIV type-1, finding an animal with similar antibody response to the virus as humans can prove difficult. A study conducted in 1998 found that the tawny-bellied cotton rat can be infected by low-level HIV-1.[7] A similar immune response to humans is activated on infection. The degree of infection may be increased by altering the co-receptors on the animal's cells, which would improve the reliability of the test subject.[7] The species was found to undergo an equivalent infection to pulmonary tuberculosis as humans.[9] This is an upgrade over the previous animal models of other small rodents and rabbits. Cotton rats combine the best traits of human-like lung granuloma formation (trait of rabbits) and inexpensive care (trait of other small rodents) to provide a suitable host for this type of study. Future research is underway to use the cotton rat for studying pulmonary tuberculosis complicated by HIV-1 due to similarities with humans in both diseases.[9] References1. ^1 {{IUCN2009.2|assessor=Linzey, A.V.|assessor2=Timm, R.|assessor3=Álvarez-Castañeda, S.T.|assessor4=Castro-Arellano, I.|assessor5=Lacher, T.|last-assessor-amp=yes|year=2008|id= 20212|title=Sigmodon fulviventer|downloaded=6 February 2010}} 2. ^1 2 {{Cite journal|last=Baker|first=Rollin H.|last2=Shump Jr.|first2=Karl A.|year=1978|title=Sigmodon fulviventer|journal=Mammalian Species|volume=94|pages=1–4}} 3. ^{{Cite journal|last=Zelditch|first=Miriam L.|last2=Carmichael|first2=Christopher A.|year=1989|title=Ontogenetic Variation in Patterns of Developmental and Functional Integration in Skulls of Sigmodon fulviventer|url=|journal=Evolution|volume=43|pages=814–824|doi=10.2307/2409309}} 4. ^{{Cite journal|last=Ahi|first=Alwynelle S.|year=1982|title=Evidence of use of vibrissae in swimming in Sigmodon fulviventer|doi=10.1016/s0003-3472(82)80211-x|journal=Animal Behaviour|volume=30|pages=1203–1206|via=}} 5. ^1 2 {{Cite journal|last=Geluso|first=Keith|last2=Hoffman|first2=Justin D.|last3=Ashe|first3=Vikki A.|last4=White|first4=Jeremy A.|last5=Bogan|first5=Michael A.|year=2005|title=Westward Expansion of the Tawny-bellied Cotton Rat (Sigmodon fulviventer) in West-central New Mexico|url=|journal=The Southwestern Naturalist|volume=50|pages=273–277|via=BioOne|doi=10.1894/0038-4909(2005)050[0273:weottc]2.0.co;2}} 6. ^1 {{Cite journal|last=Petersen|first=Michael K.|year=1973|title=Interaction Between the Cotton Rats, Sigmodon fulviventer and S. hispidus|url=|journal=The American Midland Naturalist|volume=90|pages=319–333|doi=10.2307/2424456}} 7. ^1 2 3 {{Cite journal|last=Langley|first=Raymond J.|last2=Prince|first2=Gregory A.|last3=Ginsberg|first3=Harold S.|year=1998|title=HIV type-1 infection of the cotton rat (Sigmodon fulviventer and S. hispidus)|journal=The National Academy of Sciences|volume=95|pages=14355–14360|doi=10.1073/pnas.95.24.14355|pmid=9826704|pmc=24377}} 8. ^{{Cite journal|last=Prince|first=G.A.|last2=Hemming|first2=V.A.|last3=Horswood|first3=R.L.|last4=Baron|first4=P.A.|last5=Chanock|first5=R.M.|year=1987|title=Effectiveness of topically administered neutralizing antibodies in experimental immunotherapy of respiratory syncytial virus infection in cotton rats|url=|journal=Journal of Virology|volume=61|pages=1851–1854|via=}} 9. ^1 2 {{Cite journal|last=Elwood|first=Robert L.|last2=Wilson|first2=Samuel|last3=Blanco|first3=Jorge C.G.|last4=Yim|first4=Kevin|last5=Pletneva|first5=Luba|last6=Nikonenko|first6=Boris|last7=Samala|first7=Rowena|year=2007|title=The American cotton rat: A novel model for pulmonary tuberculosis|url=|journal=Tuberculosis|volume=87|pages=145–154|via=|doi=10.1016/j.tube.2006.07.001}} Further reading
3 : Cotton rats|Mammals described in 1889|Taxonomy articles created by Polbot |
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