How Christmas Island rats became extinct


This video is called Christmas Island crabs.

From PLoS ONE:

Historical Mammal Extinction on Christmas Island (Indian Ocean) Correlates with Introduced Infectious Disease …

Abstract

It is now widely accepted that novel infectious disease can be a leading cause of serious population decline and even outright extinction in some invertebrate and vertebrate groups (e.g., amphibians).

In the case of mammals, however, there are still no well-corroborated instances of such diseases having caused or significantly contributed to the complete collapse of species.

A case in point is the extinction of the endemic Christmas Island rat (Rattus macleari): although it has been argued that its disappearance ca. AD 1900 may have been partly or wholly caused by a pathogenic trypanosome carried by fleas hosted on recently-introduced black rats (Rattus rattus), no decisive evidence for this scenario has ever been adduced.

Using ancient DNA methods on samples from museum specimens of these rodents collected during the extinction window (AD 1888–1908), we were able to resolve unambiguously sequence evidence of murid trypanosomes in both endemic and invasive rats. Importantly, endemic rats collected prior to the introduction of black rats were devoid of trypanosome signal. Hybridization between endemic and black rats was also previously hypothesized, but we found no evidence of this in examined specimens, and conclude that hybridization cannot account for the disappearance of the endemic species. This is the first molecular evidence for a pathogen emerging in a naïve mammal species immediately prior to its final collapse.

See also here.

BiologyCentric: Scientists discover key to Christmas Island’s red crab migration: here.

5 thoughts on “How Christmas Island rats became extinct

  1. Australia announces plans to save Christmas Island species

    Louise Yaxley

    Australia’s Environment Minister, Peter Garrett, has announced a rescue plan for the Christmas Island ecosystem off Australia’s north west coast.

    Mr Garrett says Christmas Island’s conservation problems are pervasive, chronic and increasing.

    He says his top priority is to prevent any further extinctions. There are fears the Island’s pipistrelle bats will die out soon.

    Mr Garrett says he can’t stand by and wait for their inevitable extinction, so he has agreed to a mission to catch the remaining animals and try to breed them in captivity. But he also warned there is a low chance of successful capture and breeding.

    There will also be an immediate attempt to save two reptile species, the blue-tailed and the forest skink.

    He also announced plans for aerial baiting of the island’s biggest threat, the yellow crazy ants.

    http://www.radioaustralianews.net.au/stories/200907/2614302.htm?desktop

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  2. Biological invasions can alter direct and indirect interactions between species, generating far-reaching changes in ecological networks that affect key ecological functions. We used model and real fruit assays to show that the invasion and formation of high-density supercolonies by the yellow crazy ant (YCA), Anoplolepis gracilipes, disrupt frugivory by endemic birds on Christmas Island, Indian Ocean. The overall handling rates of model fruits by birds were 2.2–2.4-fold lower in ant-invaded than in uninvaded rainforest, and pecking rates by two bird species declined by 2.6- and 4.5-fold, respectively. YCAs directly interfered with frugivory; their experimental exclusion from fruiting displays increased fruit handling threefold to sixfold, compounding indirect effects of ant invasion on resources and habitat structure that influence bird abundances and behaviours. This invasive ant, whose high densities are sustained through mutualism with introduced scale insects, rapidly decreases fruit handling by endemic island birds and may erode a key ecological function, seed dispersal. Because most other invasive ant species form expansive, high-density supercolonies that depend in part on association with hemipteran mutualists, the effects that we report here on avian frugivore–plant associations may emerge across their introduced ranges.

    http://rsbl.royalsocietypublishing.org/content/6/1/85.short?rss=1

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  3. Pingback: Oil spill threatens Christmas Island wildlife | Dear Kitty. Some blog

  4. Pingback: Christmas Island wildlife threatened by mining | Dear Kitty. Some blog

  5. Pingback: Christmas island wildlife, Asian or Australian | Dear Kitty. Some blog

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