Browsing by Subject "RETICULATE EVOLUTION"

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    Low-copy nuclear data confirm rampant allopolyploidy in the cystopteridaceae (Polypodiales)
    (Taxon, 2014-10-01) Rothfels, CJ; Johnson, AK; Windham, MD; Pryer, KM
    © International Association for Plant Taxonomy (IAPT) 2014. Here we present the first nuclear phylogeny for Cystopteridaceae (Polypodiales), using the single-copy locus gapCp “short”. This phylogeny corroborates broad results from plastid data in demonstrating strong support for the monophyly of the family’s three genera—Cystopteris, Acystopteris, and Gymnocarpium—and of the major groups within Cystopteris (C. montana, the sudetica and bulbifera clades, and the C. fragilis complex). In addition, it confirms the rampant hybridization (allopolyploidy) that has long been suspected within both Cystopteris and Gymnocarpium. In some cases, these data provide the first DNA-sequence-based evidence for previous hypotheses of polyploid species origins (such as the cosmopolitan G. dryopteris being an allotetraploid derivative of the diploids G. appalachianum and G. disjunctum). Most of the allopolyploids, however, have no formal taxonomic names. This pattern is particularly strong within the C. fragilis complex, where our results imply that the eight included accessions of “C. fragilis” represent at least six distinct allopolyploid taxa.
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    The utility of nuclear gapCp in resolving polyploid fern origins
    (Systematic Botany, 2008-10-01) Schuettpelz, E; Grusz, AL; Windham, MD; Pryer, KM
    Although polyploidy is rampant in ferns and plays a major role in shaping their diversity, the evolutionary history of many polyploid species remains poorly understood. Nuclear DNA sequences can provide valuable information for identifying polyploid origins; however, remarkably few nuclear markers have been developed specifically for ferns, and previously published primer sets do not work well in many fern lineages. In this study, we present new primer sequences for the amplification of a portion of the nuclear gapCp gene (encoding a glyceraldehyde-3-phosphate dehydrogenase). Through a broad survey across ferns, we demonstrate that these primers are nearly universal for this clade. With a case study in cheilanthoids, we show that this rapidly evolving marker is a powerful tool for discriminating between autopolyploids and allopolyploids. Our results indicate that gapCp holds considerable potential for addressing species-level questions across the fern tree of life. © Copyright 2008 by the American Society of Plant Taxonomists.