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Friday, June 27, 2008

Birds: What you thought you knew about their evolution is ... wrong?


From both Science Daily and New Scientist comes the word that, in the words of New Scientist's Bob Holmes (June 26, 2008),

A new study – the largest analysis of birds to date using modern genetic methods – has turned up numerous surprising relationships that will force biologists to reevaluate much of what they thought they knew about avian evolution.

[ ... ]

This new tree contains several notable surprises. For example, falcons are more closely related to songbirds than to other hawks and eagles. The closest kin of the diving birds called grebes turn out to be flamingos. And tiny, flashy hummingbirds, according to the new tree, are just a specialised form of nighthawks, whose squat, bulky bodies make them an unlikely cousin.

and in the words of Science Daily, whose drudges toil nameless (June 27, 2008):

The results of the study are so broad that the scientific names of dozens of birds will have to be changed, and biology textbooks and birdwatchers' field guides will have to be revised. For example, we now know that:

Birds adapted to the diverse environments several distinct times because many birds that now live on water (such as flamingos, tropicbirds and grebes) did not evolve from a different waterbird group, and many birds that now live on land (such as turacos, doves, sandgrouse and cuckoos) did not evolve from a different landbird group.

Similarly, distinctive lifestyles (such as nocturnal, raptorial and pelagic, i.e., living on the ocean or open seas) evolved several times. For example, contrary to conventional thinking, colorful, daytime hummingbirds evolved from drab nocturnal nightjars; falcons are not closely related to hawks and eagles; and tropicbirds (white, swift-flying ocean birds) are not closely related to pelicans and other waterbirds.

Shorebirds are not a basal evolutionary group, which refutes the widely held view that shorebirds gave rise to all modern birds.
And, summing it up,

"With this study, we learned two major things," said Sushma Reddy, another lead author and Bucksbaum Postdoctoral Fellow at The Field Museum. "First, appearances can be deceiving. Birds that look or act similar are not necessarily related. Second, much of bird classification and conventional wisdom on the evolutionary relationships of birds is wrong."
Yeah. Wrong.

Or maybe not. This analysis depends on certain assumptions about bird genomes - and the assumptions may not be correct.

Here is what we now know for sure: No one living has any sure idea how different types of birds originated. Fanatics of one method clash with the fanatics of another.

And people wonder why there is an intelligent design controversy ...

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