Birds species diversifying New Haven - Agencies The most comprehensive family tree for birds to date reveals surprising new details about their evolutionary history, U.S. researchers say. The family tree of nearly 10,000 living bird species shows when and where birds diversified, and that birds\' diversification rate has increased in the last 50 million years, challenging the conventional wisdom of biodiversity experts, Yale University reported Wednesday. \"It\'s the first time that we have -- for such a large group of species and with such a high degree of confidence -- the full global picture of diversification in time and space,\" Yale biologist Walter Jetz said. Yale researchers, along with Canadian colleagues, used fossil and DNA data combined with geographical information to produce the exhaustive family tree, which revealed unexpected information about the biodiversity of bird species. \"The current zeitgeist in biodiversity science is that the world can fill up quickly,\" co-author Arne Mooers of Simon Fraser University in Canada said. \"A new distinctive group, like bumblebees or tunafish, first evolves, and, if conditions are right, it quickly radiates to produce a large number of species. \"These species fill up all the available niches, and then there is nowhere to go. Extinction catches up, and things begin to slow down or stall. \"For birds the pattern is the opposite: Speciation is actually speeding up, not slowing down,\" he said.