The largest study ever of bird genetics has discovered some surprising facts about the avian evolutionary tree, including many that are bound to ruffle some feathers. For example, Falcons are not closely related to eagles and hawks, despite many similarities, while colorful hummingbirds that flit around in the day, evolved from a drab-looking nocturnal bird called a nightjar. In addition, songbirds and parrots are closer cousins than once thought.
Sushma Reddy of Chicago's Field Museum of Natural History, whose study appears in the journal Science, said one of the lessons we have learned is appearances seem to be very deceiving. Moreover, she said things that are quite different-looking sometimes end up being related. Reddy and colleagues studied the genetic sequences of 169 bird species in an effort to sort out family relationships in the bird family tree.
The findings challenge many assumptions about bird family relationships and suggest many biology textbooks and bird watchers' field guides may need to be changed.
Scientists believe birds, which first appeared roughly 150 million years ago, evolved from small-feathered carnivorous dinosaurs. Reddy, who worked with researchers at several other labs, said modern birds, as we know them evolved rapidly, probably within a few million years, into all of the forms we have seen. That happened 65 to 100 million years ago. Moreover, she said these quick changes have made bird evolution hard to pin down, and several smaller prior studies have led to conflicting results.
Researchers are not positively sure how any of these major bird groups were related to each other. They have tried to represent all of the major groups of birds and all of the major lineages. Their findings suggest birds can be grouped broadly into land birds, like water birds, the sparrow, like the penguin; and shore birds, like the seagull. However, there are many paradoxes within these groupings. For example, water-loving flamingos and some other aquatic birds did not evolve from water birds. Instead, they adapted to life on water. In addition, some flightless birds are grouped with birds that fly.
Reddy acknowledges the results are likely to stir debate in many circles, but she said she is confident in the findings. According to Reddy, it is a good study brings up as many questions as it answers.
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