Molecular Ecology and Evolution
Morris, Ashley B. , Ickert-Bond, Stefanie M. , Bigger, Alexandra R. , Soltis, Douglas E. , Soltis, Pamela S. .
Phylogeographic complexity and pre-Pleistocene breaks within Liquidambar styraciflua.
A rapidly growing database of phylogeographic literature for eastern North American plants and animals indicates greater spatial and temporal complexity than previously suggested. In the absence of divergence time estimates, most of these studies assume Pleistocene glaciation as the primary causal factor associated with observed phylogeographic breaks. We surveyed 80 individuals from 25 populations across the range of Liquidambar styraciflua (Altingiaceae) in the U.S., Mexico, and Guatemala, for variation in several plastid DNA regions: atpB-rbcL, psbA-trnH, psbE-petL, and trnL-F. Analyses included statistical parsimony, maximum parsimony, maximum likelihood, and Bayesian approaches. Other members of Altingiaceae were included to allow for intraspecific divergence time estimates using L. changii and Microaltingia for fossil calibration. The greatest among-population divergence occurred within the U.S., rather than between the U.S. and disjunct populations from Mexico and Guatemala. In fact, the Mexican and Guatemalan samples shared one of two most common haplotypes recovered, indicating evolutionarily recent gene flow between these two regions. Additionally, half of all populations sampled exhibited multiple haplotypes, indicating the need for increased sample sizes within populations. Furthermore, our data support previously hypothesized refugia in peninsular Florida and interior highlands as multiple source populations for modern genetic lineages. However, divergence time estimates based on fossil calibration suggest that all observed phylogeographic breaks pre-date the Last Glacial Maximum. Such ancient phylogeographic breaks in eastern North America have been suggested for both birds and fish, but, to our knowledge, the data presented here represent the first such empirical example for plants.
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1 - University of South Alabama, Department of Biological Sciences, Life Sciences Building 124, Mobile, AL, 36688, USA
2 - University of Alaska Fairbanks, Department of Botany, 907 Yukon Drive, Fairbanks, AK, 99775, USA
3 - University of Florida, Department of Botany, PO Box 118526, Gainesville, Florida, 32611, U.S.A.
4 - University of Florida, Botany, PO Box 117800, Gainesville, FL, 32611, USA
5 - University of Florida, Florida Museum of Natural History, PO Box 117800, Gainesville, FL, 32611-7800, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Boulevard B/Hilton
Date: Wednesday, July 11th, 2007
Time: 1:15 PM