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Journal of Botany
Volume 2012 (2012), Article ID 292857, 6 pages
http://dx.doi.org/10.1155/2012/292857
Research Article

Exploring Diversification and Genome Size Evolution in Extant Gymnosperms through Phylogenetic Synthesis

1Department of Biology, University of Florida, Gainesville, FL 32611, USA
2School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611, USA
3Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA

Received 2 June 2011; Accepted 20 September 2011

Academic Editor: Hiroyoshi Takano

Copyright © 2012 J. Gordon Burleigh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Gymnosperms, comprising cycads, Ginkgo, Gnetales, and conifers, represent one of the major groups of extant seed plants. Yet compared to angiosperms, little is known about the patterns of diversification and genome evolution in gymnosperms. We assembled a phylogenetic supermatrix containing over 4.5 million nucleotides from 739 gymnosperm taxa. Although 93.6% of the cells in the supermatrix are empty, the data reveal many strongly supported nodes that are generally consistent with previous phylogenetic analyses, including weak support for Gnetales sister to Pinaceae. A lineage through time plot suggests elevated rates of diversification within the last 100 million years, and there is evidence of shifts in diversification rates in several clades within cycads and conifers. A likelihood-based analysis of the evolution of genome size in 165 gymnosperms finds evidence for heterogeneous rates of genome size evolution due to an elevated rate in Pinus.