Grusz, Amanda L. , Windham, Michael , Pryer, Kathleen M. .
A Cheilanthes by any other name: Evolutionary complexity in the New World myriopterid clade (Pteridaceae).
The New World is host to a diversity of xeric-adapted fern lineages that utilize a variety of morphological, physiological, and reproductive mechanisms to withstand seasonal drought. Most of these “desert ferns” belong to a large (400-500 species), globally distributed clade informally known as the “cheilanthoids.” Many genera within this clade have recently been shown to be polyphyletic, and species currently assigned to the genus Cheilanthes are scattered across the entire cheilanthoid phylogeny. However, there is one well-supported subclade of Cheilanthes s.l., the myriopterids, that encompasses most North American (and a few South American) species. This subclade includes approximately 50 described taxa, many of which are polyploid and notable for their tendency toward apomictic reproduction. Reticulate evolution, morphological homoplasy, and cryptic species abound among myriopterid ferns, complicating attempts to resolve relationships within the clade. To provide additional insight on the evolution of this group, we analyzed plastid (trnG-trnR, atpA, and rbcL) and nuclear (gapCp) DNA sequences from a broad sample (>80%) of myriopterid taxa. These data were used to generate a robust estimate of phylogenetic relationships within the group, which sheds significant light on the roles of hybridization, polyploidy, and apomixis in the evolutionary diversification of the lineage. Our well-resolved and strongly supported phylogenetic hypothesis provides a solid foundation for future studies involving divergence dating and the reconstruction of morphological, environmental, and life history traits within myriopterid cheilanthoids.
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1 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Alpine B/Snowbird Center
Date: Monday, July 27th, 2009
Time: 10:45 AM