"By modifying habitats and creating bridges and barriers between land masses, climate change and tectonic events [land mass movements] are believed to have important consequences for diversification of terrestrial organisms," wrote two Duke University evolutionary biologists in a paper posted on the Feb. 20, 2003, edition of Science Express, the on-line version of the journal Science.
"Such consequences should be most evident in the phylogenetic histories of groups that are ancient, widespread and diverse. The squirrel family is one of the very few mammalian families endemic to Eurasia, Africa, North America and South America, and is ideal for examining these issues," continued John M. Mercer, a Duke assistant professor of the practice of biology, and V. Louise Roth, a Duke associate professor of biology and biological anthropology and anatomy.
In research supported by the National Science Foundation and Duke, Mercer and Roth analyzed DNA differences among 50 of the 51 present-day squirrel genera to deduce their interrelationships, leaving out only one Indian flying squirrel that is too rare to study. They determined squirrel family ties by statistically analyzing representative DNA sequences extracted from live animals or preserved museum specimens. To deduce how long ago and where various lineages lived, they also used fossil dating records and "molecular clock" analyses, which predict how DNA sequences change over time.
Comparing their findings with geological evidence, they noted "an interesting interplay between global change and the way this par
Contact: Monte Basgall