1,000 new bird species?

2007 February 19
by David J. Ringer

DUNCANVILLE, TEXAS — A paper titled “Comprehensive DNA barcode coverage of North American birds” recently appeared in Molecular Ecology Notes and may cause a whole new wave of splits and lumps in the bird world.

The authors suggest that, of 643 North American bird species sampled, fifteen currently recognized species actually contain populations with significant genetic differences. This, of course, suggests that the populations have not interbred for quite a long time, which could make them different species under the Biological Species Concept.

Extrapolating their results, the authors suggest there could be 1,000 as-yet unrecognized bird species around the world.

But before you get carried away by visions of armchair lifers, read on. The team’s research also suggests that some populations currently recognized as species (like some of the big gulls and various waterfowl) are very, very similar genetically.

It will be interesting to see how the ornithological community reacts to these data. One of the problems with Charles Sibley’s work, for example, was that he assumed genes change at relatively predictable rates as populations diverge, which apparently is not true.

That, as you can see, has bearing on this new study. Can we define bird species solely by measuring their genetic divergence from one another? Probably not, and the authors of the paper do not advocate such a simplistic approach. But all the same, this study probably foreshadows more big changes to come. If nothing else, it’s good news for the field guide publishers, who will not run out of excuses for new editions for many more years.

This research on birds is part of the Barcode of Life project, which I had not heard of before today. Apparently, the idea is to reduce DNA samples to a string of digits that is unique for each species.

This “barcode” encodes only a tiny fraction of all the information contained in a species’ DNA, of course, and I’m left wondering how scientists know which sections to choose. If you had a very short, incomplete list of my sister’s and my physical attributes, you might conclude that we were the same individual. In fact, you’d be looking at all the wrong things. However, I’m sure this objection is due to my ignorance of the process and not a problem with the theory.

Speaking of misunderstandings, when I first read this article’s description of a futuristic handheld device that allows identification of any species, I imagined Star Trek explorers scanning alien forests for life signs. (“Yep, my scans show three Blackburnian Warblers and a Scarlet Tanager. What’d you get?”) Surely, though, what the author means is that such a device could identify a species based on a DNA sample, which is a bit different from Star Trek but still pretty cool. Ever wonder what kind of bird a feather came from? Help could be on the way.

Yes, we live in interesting times my friends.

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