Systematics Section / ASPT
Bell, Charles , Soltis, Pamela S. , Soltis, Douglas E. .
The age of the angiosperms: a Bayesian perspective.
The age of angiosperms has long been of interest to botanists
and evolutionary biologists. Many previous efforts to date evolutionary
divergences within angiosperms using a molecular clock have yielded age
estimates that are grossly inconsistent with the fossil record. In this
study, we investigated the age of angiosperms using a Bayesian approach.
The Bayesian “relaxed-clock” method allows a range of values for
among-lineage rate of substitution, from a nearly clock-like behavior to
a condition in which each branch is allowed an optimal substitution
rate. A phylogeny derived from analysis of five genes, from all three
genomes, and 71 taxa was used as a backbone topology. The effects on age
estimates for different genes, single gene vs. concatenated datasets,
and the inclusion and assumptions of fossils as age constraints were
examined. In addition, the influence of prior distributions on estimates
of divergences times was also explored. These results indicate that
widely divergent age estimates can result from different sources of data
and the inclusion of temporal constraints to topologies. The results
from our Bayesian analyses are also compared with other estimation
procedures that relax the assumption of a strict molecular clock.
1 - University of Florida, Department of Natural History, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
2 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
divergence time estimates
Presentation Type: Paper
Location: Cottonwood B (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 1:30 PM