Birds of Different Feathers Evolve Together
Are pigeons like parrots? Are hummingbirds like hawks? And are falcons unlike eagles? Scientists are all a-flutter after results of a massive genetic comparison of birds has put some members in unlikely pigeonholes. “The largest ever study of bird genetics has not only shaken up but completely redrawn the avian evolutionary tree,” said Science Daily. “The study challenges current classifications, alters our understanding of avian evolution, and provides a valuable resource for phylogenetic and comparative studies in birds.”
That last clause seems unjustifiably optimistic considering what news reports are saying about this study. Here is a short list of quotations gleaned from Science Daily, New Scientist, Reuters, and the blog Living the Scientific Life. They give you a sense of the upheaval among scientists upon finding out that birds’ appearances tell little about their supposed evolutionary history.
- The findings challenge many assumptions about bird family relationships and suggest many biology textbooks and bird-watchers’ field guides may need to be changed.
- One of the lessons we’ve learned is appearances seem to be very deceiving. Things that are quite different-looking sometimes end up being related.
- [Sushma] Reddy said these quick changes have made bird evolution hard to pin down, and several smaller prior studies have led to conflicting results. “We didn’t have a good sense of how any of these major bird groups were related to each other,” said Reddy, who worked with researchers at several other labs.
- Their findings suggest birds can be grouped broadly into land birds, like the sparrow; water birds, like the penguin; and shore birds, like the seagull. But there are many paradoxes within these groupings.
- This analysis effectively redraws avian phylogeny, or family tree, thus shaking up our current understanding of the early, or “deep”, evolutionary relationships of birds.
- So why is avian taxonomy suddenly in such a state of upheaval?
- These analyses reveal two major findings: First, the classifications and conventional wisdom regarding the evolutionary relationships among many birds is wrong. Second, birds that have similar appearances or behaviors are not necessarily related to each other.
- Shorebirds are not a basal evolutionary group, which refutes the widely held view that shorebirds gave rise to all modern birds.
- This research also affect publishers and birders because biology textbooks and birdwatching field guides will have to be rewritten.
- 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.
- In fact, the new tree ended up regrouping about a third of all the orders in earlier phylogenies of birds.
- For example, the new tree puts an order of flying birds, the tinamous, squarely in the midst of the flightless ostriches, emus and kiwis. If true, this implies either that flightlessness evolved at least twice in this lineage, or else that the tinamous re-evolved flight from a flightless ancestor. “A lot of us actually don’t believe their result,” says [Joel] Cracraft, who says that further studies will be needed to resolve the issue.
- Similarly, distinctive lifestyles (such as nocturnal, raptorial and pelagic, i.e., living on the ocean or open seas) evolved several times.
- 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.
So what are scientists to believe – their eyes or their phylogenetic software? The results defy common-sense arrangements. They render morphological classification (the way Darwin and his followers did it before genetics became a science) unreliable. That is why Cracraft and others are finding it hard to believe. The anonymous writer of the “Living the Scientific Life” blog tried to explain why the data are so confusing:
So why is avian taxonomy suddenly in such a state of upheaval? The precise evolutionary relationships between major groups of birds have long been contentious because they underwent an explosive radiation event sometime between 65 million and 100 million years ago. Nearly all of the major avian groups arose within just a few million years — a very short period of evolutionary time. As a result, those groups of birds, such as parrots, doves and owls, that are united by distinct morphological characteristics seem to have appeared suddenly because there are few, or no, known evolutionary intermediates that provide clues to their deeper relationships with other avian groups.
She thus tried to “save the appearances” within the evolutionary framework by appealing to a lack of data. The hidden events that led to the “emergence” of groups of birds left no trace in the record. What’s more, the new phylogeny requires more appeals to “convergent evolution” Now, scientists will have to believe that unlikely events occurred multiple times in unrelated groups.
The five-year “Early Bird” study was part of the “Assembling the Tree of Life” (AToL) research project funded by the National Science Foundation (10/30/2002, 09/08/2006).
This entry falls in the category of “Everything you know is wrong.” Throw out the field guide and forget everything your teacher told you about how birds evolved. Now we know “the truth” about bird evolution. Evolutionists play this game every once in awhile to look busy. It provides job security. You need the evolutionist to interpret the world for you lest you be misled by your senses and common sense.
Evolutionary theory is looking more and more like divination (cf. 06/12/2008). The mystery religion of understanding the deep relationships in Darwin’s mythical tree requires faith in the professionals. Ordinary bird-watchers should not try this at home. It requires the skill of the duly possessed shaman who alone has the power to conjure up the image of Charlie in the crystal ball of the genes.