This one puzzles me

Human-caused climate change appears to have driven the Great Barrier Reef’s only endemic mammal species into the history books, with the Bramble Cay melomys, a small rodent that lives on a tiny island in the eastern Torres Strait, being completely wiped-out from its only known location.

Marsupials are of course mammals. Rodents are not marsupials. And Australia is rather famous for not having rodents but for having marsupials.

So, first order thought would be that this was an introduced species in the first place.

Second order thought is that this might not be quite true up around the Torres Strait and Cape York. Because that’s where those two biospheres, the one with rodents in and the one with marsupials in, sorta meet. Umm, maybe: as you can tell I’m not claiming expertise here.

Third thought is that any species which lives only on one 5 hectare (or whatever) island isn’t going to have a long run as a species. You only need a bit of erosion and it’s gone. Or a decent tsunami or summat.

Not quite the importance to it that some are claiming then I would have thought.

It is also the first recorded extinction of a mammal anywhere in the world thought to be primarily due to human-caused climate change.

Unconvinced to put it mildly.

Aha! Via twatter, I am enlightened:

The small population size means genetic drift, disease and introduced species all pose a threat to the species.

Habitat loss via erosion of the cay is the single most important threat, particularly given that sea levels are predicted to rise thanks to climate change. Bramble Cay is by no means stable. Between 1958 and 1987, the cay decreased in size; but in 2011 it had returned to a size comparable to 1958.

While the size of the cay varies, the vegetation on it is shrinking, and this might be the main cause of the melomys’ decline.

Climate change and rising sea levels not so much then perhaps?

4 thoughts on “This one puzzles me”

  1. So Much For Subtlety

    I am pretty sure Australia and New Zealand both have native rat species. And native bats.

    Australia has indigenous placental mammals from two orders: the bats—order Chiroptera—represented by six families; and the mice and rats—order Rodentia, family Muridae. Bats and rodents are relatively recent arrivals to Australia; bats are present in the fossil record only from as recently as 15 MYA, and probably arrived from Asia.[citation needed] There are only two endemic genera of bats,[45] although 7% of the world’s bats species live in Australia.[citation needed] Rodents first arrived in Australia 5–10 MYA,[45] undergoing a wide radiation to produce the species collectively known as the “old endemic” rodents.[46] The old endemics are represented by 14 extant genera.[citation needed] A million years ago, the rat entered Australia from New Guinea and evolved into seven species of Rattus, collectively called the “new endemics”.

    Rather than climate change being a threat to local native rats I would assume Norwegian rats, cats and foxes were the first order of suspects.

    But I find it hard to believe that an island so small could ever have supported a stable native rat population long enough for it to have evolved into a separate species.

  2. Note that they actually say, this bad thing might come true because sea-level is predicted to rise.

    Not that it has happened because sea-level has risen – too easy to disprove, they don’t like hostages to fortune like that.

    So it’s just computer models again.

    Back to sleep.

  3. If you read the original article (https://www.ehp.qld.gov.au/wildlife/threatened-species/documents/bramble-cay-melomys-survey-report.pdf), it says the following. Caveat: I’ve only skimmed it.

    1. The species seems to have disappeared from Bramble Cay.

    2. The cause is likely several inundations of the island over the past decade.

    3. “new information is provided in support of a previously presented hypothesis that the Fly River delta of Papua New Guinea is a possible source of the original melomys population on Bramble Cay, which would imply that the Bramble Cay melomys or a closely related species may occur in the Fly River region”

    4. “Available information about sea-level rise and the increased frequency and intensity of weather events producing extreme high water levels and damaging storm surges in the Torres Strait region over this period point to human-induced climate change being the root cause of the loss of the Bramble Cay melomys.”

    Thus, the original report actually states that the species could well exist in other locations; the species quite possibly wasn’t wiped out, and quite likely didn’t evolve in that location. (In biology, there is a continual debate about the definition of “species”, and whether a given “closely related species” is really a different species at all. This debate gets political at times, for reasons I don’t fully understand.)

    Personal view (out on the table here):
    a. Climate change is real.
    b. That it’s human-induced is likely.
    c. That we’re all doomed unless we do something dramatic about it is less likely.
    d. That we will actually do something dramatic about it is highly unlikely. (Words… words… words!)
    e. If that means humans therefore die out as a species, so be it.

  4. Bloke in Costa Rica

    If we make it through the next few decades (couple of centuries, max) without either greens or goat-botherers destroying civilisation, then if we decide we don’t want the planet to warm we’ll just tell it not to.

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