-------------------------------------------------------------------------------------
Here's a relatively recent online paper (pdf) in which the authors report evidence from the mitochondrial DNA of both the N. American and Cuban Ivory-bill to measure their relationship to one another, as well as to other Campephilus woodpeckers:
http://www.hmnh.harvard.edu/ivorybilled.pdf
--- a bit technical, but among other things they do make the point that they have established a "DNA barcoding resource" which can be used in identifying the source of future (genetic) material that might require testing.
...and now for something totally different, have to give credit to "DocMartin" over at BirdForum for giving me a chuckle on Tue. with the following:
................................................
- Knock knock
- Who's there?
- Ivor
- Ivor who?
- Ivory-billed Woodpecker
- Can you prove that?
- No I kent
...............................................
...okay, so maybe I'm an easy audience, or just not getting enough sleep lately!!
anyway, for now, back to sipping some (cheap) red wine, munching M&Ms, and looking over some maps of the southeast U.S., while doing a little arithmetic.
---------------------------------------------------------------------------------
4 comments:
The most significant bit in that study is that the Cuban Ivorybill is as different from the North American Ivorybill as either Ivorybill is from the Imperial. This that (a) the cluster of "Ivorybills" probably represent THREE closely related but distinct species (Imperial, North American Ivorybill, and Cuban Ivorybill), not just two, and (b) the Ivorybill was NOT introduced to Cuba by humans as Jackson hypothesized.
Let's hope that when the AOU revises the checklist to split the Ivorybill they don't give us another monstrous name like "North American Ivory-billed Woodpecker." Having to deal with "Salt Marsh Sharp-tailed Sparrow" is atrocious enough already, thank you! How about, maybe, just calling the group the "Ivorybills" instead of the "Ivory-billed Woodpeckers?" That's what everyone calls them anyway. Then we could have simply the Imperial Ivorybill, the Northern Ivorybill, and the Cuban Ivorybill ("Northern" instead of "North American" since Mexico is North America, too).
That's a really interesting paper. I like that they thanked Jerome Jackson, even though they refuted his hypothesis about the Cuban Ivory Bill. I did not see any molecular analysis of the Magellanic Woodpecker--I found that odd. I've seen the Magellanic, Imperial, and IBWO referred to as Campephilus sensu strictu (in the narrow sense--see this ID Frontiers post), but perhaps the Magellanic is no longer considered to be closely related to the northern Ivory-bills. (Winkler's work on Woodpeckers does place the three in sequence.) Anybody know anything about that?
I was also curious to see them postulating colonization of Cuba from the Yucatan--I would think Florida would have been closer. During Pleistocene glacial maxima, the straits of Florida were pretty narrow, and South Florida would have been much larger. But perhaps the Yucatan straits would have been about as wide, or even narrower. I love biogeography--there are a couple of interesting popular works out there: The Monkey's Bridge, by Wallace--about Central America, and After the Ice Age, by Pielou--about North America. Neither mentions the Campephilus woodpeckers, that I recall, but they do get you thinking about how different things were during the glacial periods--especially sea levels.
just one minor, cautionary comment, since people so often find genetic arguments very compelling: I think it worth noting that this sort of genetic analysis is always based on certain assumptions being made (which may seem totally reasonable at the time), and on probabilistic analysis. That means there is always a certain leftover probability the conclusions are simply mistaken, or that 100 years from now the assumptions made or analysis carried out will have been demonstrated false as our understanding of genetics advances. (Of course this could be said for most of science!)
I think they hypothesize colonization from the south because during the glacial maximum the "tropics" were farther south, and that would seem the likeliest source direction for a genus that is primarily tropical. They could have then spread north across the very narrow Florida Strait into what is now the continental US, become isolated when sea levels rose, and diverged genetically for the last million years.
Post a Comment