Bird family tree created - Throws up surprising results14/11/2012 13:40:27 Bird tree tells new tale of evolution
November 2012. Using the world's first family tree linking every known bird species, scientists from Canada's Simon Fraser University amongst others have discovered that birds appear to be accelerating their rate of evolution. The finding is contrary to the scientists' expectations.
They spent five years creating their tree, using millions of years' worth of fossil data stretching back to the Age of the Dinosaurs, DNA data and supercomputers. They then mapped where on Earth and when in history birds' diversification took place.
9993 bird species
New species appearing faster
"Perhaps birds are special," theorizes Mooers. "Maybe they're so good at getting around they can escape local competition from relatives and start anew elsewhere, producing bursts of new species at different times and in different parts of the globe."
The authors have also discovered that birds' speciation rate doesn't drop off the further they are from the equator. Since three quarters of all birds are found near the equator, it was expected that speciation there would be more common.
"We know the tropical biome has been shrinking during the last 15 million years," says Joy. "Perhaps, just as bushtits bunch together closely at night, bird species have clustered together in the tropics as their habitat shrunk."
"We need to think a lot more about how Earth's changing climate has led to current distributions," says Mooers. "It's a lovely conundrum."
Other highlights of new bird species study
Avian assemblages in Australia, Southeast Asia, Africa and Madagascar have low averages of diversification compared to the global mean. These regions also harbour substantially fewer than expected of the 25 per cent of species with the highest diversification rate.
High diversification rates and large relative prevalence of top-diversification-rate species are found throughout higher latitudinal North America, parts of north Asia and southwest South America. These are the main breeding areas of several of the rapidly radiating bird species.
Complete family tree of all birds - Click on the image to see a larger version at Birdtree.org