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Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
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ScienceShot: A Tree for All Birds
31 October 2012 2:05 pm
From finches to flycatchers, songbirds are the poster children for avian diversity. But songbirds aren't the only reason birds are so varied and interesting: Bursts of new species appeared among island birds, waterfowl, woodpeckers, hummingbirds, and gulls, among others, at various times during avian evolution, researchers report online today in Nature. A new avian family tree, represented here as a circle, reveals this increasing rate of diversification of feathered creatures during the past 50 million years. At the circle's midpoint sits the avian ancestor; lines branching out from the center reveal how and when new species arose. The concentric shaded areas each represent 20 million years, and the rim, with its dense array of tips, shows the world of birds today. The lines are color-coded to designate how fast new species arose along that lineage—blue being the slowest and red being the fastest. Researchers compiled this tree over 5 years, using genetic data already in public databases and other information to estimate how the known 9993 bird species are related to one another. They studied the ranges of all the birds, looking for geographic patterns of bird evolution. Some bird lineages, such as woodpeckers, split into new species often, while nearby groups, such as hornbills, did not, they note. More diversification occurred in the Western Hemisphere compared with the Eastern Hemisphere. The tropics, despite their current species richness, were not diversification hotbeds but likely have so many species because the ecosytems there have been around for such a long time, says study leader Walter Jetz, an ornithologist at Yale University.
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