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| Image by Arne Mooers (SFU), Gavin Thomas (Sheffield) and Cody Shrank (Yale |
The researchers relied heavily on fossil and DNA data, combining them with geographical information to produce the exhaustive family tree, which includes 9,993 species known to be alive now. Analysis of the family tree shows when and where birds diversified ? and that birds? diversification rate has increased over the last 50 million years, challenging the conventional wisdom of biodiversity experts.
??The current zeitgeist in biodiversity science is that the world can fill up quickly,? says biologist and co-author Arne Mooers of Simon Fraser University in Canada. ?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.??
The researchers attribute the growing rate of avian diversity to an abundance of group-specific adaptations. They hypothesize that the evolution of physical or behavioral innovations in certain groups, combined with the opening of new habitats, has enabled repeated bursts of diversification. Another likely factor has been birds? exceptional mobility, researchers said, which time and again has allowed them to colonize new regions and exploit novel ecological opportunities.Source:?
The global diversity of birds in space and time
W. Jetz, G. H. Thomas, J. B. Joy, K. Hartmann, A. O. Mooers doi:10.1038/nature11631,
URL: http://www.nature.com/nature/journal/v491/n7424/full/nature11631.html
Source: http://lansingwbu.blogspot.com/2012/11/the-family-tree-of-all-birds.html
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