"When you put the molecular data together with other lines of evidence, it suggests that maybe they didn't move as fast as we previously thought," said James Clark, H.L. Blomquist Professor of Biology at Duke's Nicholas School of the Environment and Earth Sciences.
"Maybe the species that are growing far to the north today weren't far to the south during the last glacial," Clark said in an interview. "Maybe, in fact, they were further north near the edge of the ice and therefore didn't have to migrate as fast."
A talk on the research by Clark, Clark's research associate Jason McLachlan and associate professor of biology Paul Manos will be presented at a session beginning at 1:30 p.m. on Wednesday, Aug. 4, in Meeting Room D136 of the Oregon Convention Center during the Ecological Society of America's 2004 annual meeting in Portland.
In an interview, Clark said fossil evidence has led many scientists to conclude that many tree species now occupying former glaciated areas migrated north over an interval of a few thousand years from deep southern refuges along the southern Atlantic and Gulf coastal regions.
His and some other research groups have challenged that interpretation previously, although their objections "were never really taken seriously," Clark said. "One of the main issues for us was the fact that when you start to look at how far seeds disperse for modern trees and put that together with models of population spread, it's very difficult for a population of trees to move that fast."