Overview

Distribution

Range Description

This species is found only on Amami-oshima island, of the Amami Islands in the Ryukyu Archipelago of Japan. Since 1980, the species has become restricted to the central part of Amami-oshima (Japan RDB, 2002). Currently the species is found in the southwest of Amami-oshima, but there is an isolated population in the northeast (Abe, et al., 2005). Its elevational range is from sea level up to 500 m asl.
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
The species prefers secondary broad-leaved forests, although it can also be found in intact forests (Abe, et al., 2005). It has not been observed in plantations.

Systems
  • Terrestrial
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Molecular Biology and Genetics

Genetics

Genetic Pecularity

On 22nd Feb 2012, NewScientist reported following information about genetic pecularity:

Male Japanese Ryukyu spiny rats (Tokudaia osimensis) lack a Y chromosome.

Source: http://www.newscientist.com/article/mg21328535.100-mens-y-chromosome-is-not-about-to-go-extinct.html

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
B1ab(iii,v)

Version
3.1

Year Assessed
2008

Assessor/s
Ishii, N. & Kaneko, Y.

Reviewer/s
Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Endangered as the extent of occurrence is less than 5,000 km², its range is severely fragmented, and there is a continuing decline in the extent and quality of the species' habitat due to deforestation, and a decline in the number of individuals due to predation and competition with introduced species.

History
  • 2000
    Endangered
  • 1996
    Endangered
  • 1996
    Endangered
    (Baillie and Groombridge 1996)
  • 1994
    Vulnerable
    (Groombridge 1994)
  • 1990
    Endangered
    (IUCN 1990)
  • 1988
    Indeterminate
    (IUCN Conservation Monitoring Centre 1988)
  • 1986
    Indeterminate
    (IUCN Conservation Monitoring Centre 1986)
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Population

Population
The species was common on Amami-oshima until the 1960s, when the population declined. The population has been shown to decline with reductions of chinquapin seedlings following some typhoons (Abe, et al., 2005).

Population Trend
Decreasing
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Threats

Major Threats
Habitat destruction has severely decreased the available forest habitat on the island (Japan RDB, 2002). Feral cats and dogs present on the island are known to predate this species (Japan RDB, 2002; Abe, et al., 2005). Introduced mongoose (Herpestes javanicus) are a major predator on the island, and competition also exists with Rattus rattus.
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Management

Conservation Actions

Conservation Actions
It is present in Amami Quasi National Park. The control of introduced predators is needed. It is listed as Endangered (EN) in the Japanese Red List (2007).
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Wikipedia

Ryukyu spiny rat

The Ryukyu spiny rat (Tokudaia osimensis) is a species of rodent in the family Muridae. It is found only on Amami (Ryukyu islands) in Japan. Its natural habitat is temperate forests. They have lost their Y chromosome.[1]

References[edit]

  1. ^ KAYOKO GEJI (August 23, 2012). "Y chromosome losing all genes, but men won't become extinct". The Asahi Shimbun. Retrieved 11 January 2014. 


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