Tuesday, August 17, 2010

Where have all the dodos gone?

Where have all the dodos gone?

Dead as a dodo ... you've heard that phrase before, but is the dodo really gone? Is it really extinct?

Well, is our good friend, Raphus cucullatus, aka Didus ineptus, really gone? If so, how would you know, statistically speaking that is?

When I was in Canberra recently, I learned a little bit more about just what it means to be extinct, and it's not quite as clear-cut as you may think.

While attending some meetings for the Biodiversity Heritage Library (specifically, the kick-off meeting for the BHL-Australia project), a colleague, knowing my fondness for dodos, gave me a copy of Decision Point (a monthly magazine of the Applied Environmental Decision Analysis research hub.

In this April 2010 issue was a great article by Tracy Rout, "Dead as a Dodo?" that gave some very interesting statistical models of how scientists can determine if a species is, indeed, extinct.

By using a number of quantifiable metrics (e.g. confirmed sightings, time since last confirmed sighting, commonality of sighting, etc.), the statistical probability that a given species is extinct can be calculated and assigned a value. For the dodo, the likelihood of finding one (outside of my blogposts and avatars of course!) is a tiny 3.07 x 10^-6.

Why is this important? Well, for some species with a high probability of extinction, there's not really much value in this calculation). But for other species, where there is still a statistical possibility of being extant, a range of other financial and environmental management factors come into play.

For instance, if it was known that the ivory billed woodpecker might still be alive, actions could be taken to preserve the habitat and investigate locating the survivors (sadly, the statistical probability of the ivory bill still being extant is a minimal 1.78 x 10 ^-13 - actually lower than the dodo because there were more historic sightings of the ivory bill than of dodos).

So, though there isn't much hope for the dodo or the ivory billed woodpecker, there are still surprises, the so-called "Lazarus Species", thought to be extinct, and in probability extinct, but which rise from the ultimate exit. Rout and his co-authors point out the yellow-spotted bell frog as an example (and don't forget one of my favorite species, the coelacanth).

For more, see the full article:
Rout, TM, D Heinze & M McCarthy (2010). Optimal allocation of conservation resources to species that may be extinct. Conservation Biology. DOI: 10.111/j.1523-1739.2010.01461.x

1 comment:

Chris Freeland said...

Fascinating post! But the real question is - were any other extinct animals as tasty as the dodo?