Boore said, however, that comparing DNA sequences directly may not be the best method, because the same mutation could show up more than once, throwing into doubt any conclusions about plants being from the same lineage. He has had great success looking at gene rearrangements within the mitochondrial genomes of animals - at genes that switch places, flip or duplicate.
"When gene order rearrangements define some specific evolutionary branching, we've judged that those are very, very powerful characters because they are very unlikely to rearrange in the same way in two different lineages," Boore said. "We feel that when we find gene rearrangements, we are confident that that part of the tree is well resolved."
Following mitochondrial gene rearrangements over time, he and his team several years ago established convincingly that the myriapods - millipedes and centipedes - are not the ancestor of modern insects, as most people assumed. Rather, these many-segmented creatures emerged from the ocean earlier than insects. Crustaceans - crabs and lobsters - are more closely related to insects than are millipedes and centipedes, he said.
Boore, Mishler and other members of the collaboration hope to find chloroplast as well as plant mitochondrial genes that change slowly over time, and thus would be suitable for assessing long-term evolutionary change, as well as fast-mutating genes suitable for studying more recent evolution.
Other principal investigators on the grant are research botanist Alan R. Smith of UC Berkeley's University Herbarium, Charles O'Kelly of the Bigelow Laboratory for Ocean Sciences in Maine, Paul G. Wolf of Utah State University, Karen Renzaglia of Southern Illinois University, Dina Mandoli and Richard Olmstead of the Unive
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Contact: Robert Sanders
rls@pa.urel.berkeley.edu
510-643-6998
University of California - Berkeley
25-Nov-2002