Using new genomic sequences from eight yeast species, the group in Carroll's lab, which was led by post-doctoral fellows Antonis Rokas, Barry L. Williams and Nicole King, were able to assess the reliability of trees constructed using more than 100 genes. The result was a single tree with no doubt.
"We were shocked. We didn't expect such an unprecedented level of resolution," says Rokas. "Some genes give you one story, some genes give you another, but with enough of them together we get a single picture."
Apparently, the catch with the single gene model is that some of the thousands of nucleotides that make up a gene can be biased as natural selection acts on the gene to fulfill a certain role. "Each gene carries information concerning both history and selection. Genes alone are biased, but together their shared history overrides each genes' unique bias and provides a surprisingly strong picture of evolution," says Williams.
The implications of the study are exciting, and provide encouraging news for the future of understanding the tree of life, says Carroll. As the data sets get larger the influence of variation caused by natural selection becomes small enough that true historical relationships can be worked out.
"The problem is that molecules don't all change in the same way," says Carroll. "Now, with whole genomes being deciphered at a rapid clip, long-standing qu
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Contact: Sean B. Carroll
sbcarroll@wisc.edu
608-262-6191
University of Wisconsin-Madison
22-Oct-2003