Abstract Detail

Systematics Section / ASPT

Bell, Charles [1], Soltis, Pamela S. [1], Soltis, Douglas E. [2].

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

Keywords:
Bayesian phylogenetics
angiosperms
divergence time estimates
fossils.

Presentation Type: Paper
Session: 58-1
Location: Cottonwood B (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 1:30 PM
Abstract ID:319