Browsing by Subject "BAYESIAN PHYLOGENETIC INFERENCE"

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    Maidenhair ferns, adiantum, are indeed monophyletic and sister to shoestring ferns, vittarioids (Pteridaceae)
    (Systematic Botany, 2016-01-01) Pryer, KM; Huiet, L; Li, F; Rothfels, CJ; Schuettpelz, E
    © 2016 by the American Society of Plant Taxonomists. Across the tree of life, molecular phylogenetic studies often reveal surprising relationships between taxa with radically different morphologies that have long obscured their close affiliations. A spectacular botanical example is Rafflesia, a holoparasite that produces the largest flowers in the world, but that evolved from tiny-flowered ancestors within the Euphorbiaceae. Outside of parasitic lineages, such abrupt transformations are rarely seen. One exception involves the "maidenhair ferns" (Adiantum), which are quintessential ferns: beautifully dissected, terrestrial, and shade loving. The closely related "shoestring ferns" (vittarioids), in contrast, have an extremely simplified morphology, are canopy-dwelling epiphytes, and exhibit greatly accelerated rates of molecular evolution. While Adiantum and the vittarioids together have been shown to form a robust monophyletic group (adiantoids), there remain unanswered questions regarding the monophyly of Adiantum and the evolutionary history of the vittarioids. Here we review recent phylogenetic evidence suggesting support for the monophyly of Adiantum, and analyze new plastid data to confirm this result. We find that Adiantum is monophyletic and sister to the vittarioids. With this robust phylogenetic framework established for the broadest relationships in the adiantoid clade, we can now focus on understanding the evolutionary processes associated with the extreme morphological, ecological, and genetic transitions that took place within this lineage.
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    Patterns of diversification in the xeric-adapted fern genus myriopteris (Pteridaceae)
    (Systematic Botany, 2014-01-01) Grusz, AL; Windham, MD; Yatskievych, G; Huiet, L; Gastony, GJ; Pryer, KM
    Strong selective pressures imposed by drought-prone habitats have contributed to extensive morphological convergence among the 400 + species of cheilanthoid ferns (Pteridaceae). As a result, generic circumscriptions based exclusively on macromorphology often prove to be non-monophyletic. Ongoing molecular phylogenetic analyses are providing the foundation for a revised classification of this challenging group and have begun to clarify its complex evolutionary history. As part of this effort, we generated and analyzed DNA sequence data for three plastid loci (rbcL, atpA, and the intergenic spacer trnG-trnR) for the myriopterid clade, one of the largest monophyletic groups of cheilanthoid ferns. This lineage encompasses 47 primarily North and Central American taxa previously included in Cheilanthes but now placed in the recircumscribed genus Myriopteris. Here, we infer a phylogeny for the group and examine key morphological characters across this phylogeny. We also include a brief discussion of the three well-supported Myriopteris subclades, along with a review of reproductive mode and known ploidy levels for members of this early diverging lineage of cheilanthoid ferns. © Copyright 2014 by the American Society of Plant Taxonomists.
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    Toward a monophyletic Notholaena (Pteridaceae): Resolving patterns of evolutionary convergence in xeric-adapted ferns
    (Taxon, 2008-01-01) Rothfels, CJ; Windham, MD; Grusz, AL; Gastony, GJ; Pryer, KM
    Cheilanthoid ferns (Pteridaceae) are a diverse and ecologically important clade, unusual among ferns for their ability to colonize and diversify within xeric habitats. These extreme habitats are thought to drive the extensive evolutionary convergence, and thus morphological homoplasy, that has long thwarted a natural classification of cheilanthoid ferns. Here we present the first multigene phylogeny to focus on taxa traditionally assigned to the large genus Notholaena. New World taxa (Notholaena sensu Tryon) are only distantly related to species occurring in the Old World (Notholaena sensu Pichi Sermolli). The circumscription of Notholaena adopted in recent American floras is shown to be paraphyletic, with species usually assigned to Cheilanthes and Cheiloplecton nested within it. The position of Cheiloplecton is particularly surprising - given its well-developed false indusium and non-farinose blade, it is morphologically anomalous within the "notholaenoids". In addition to clarifying natural relationships, the phylogenetic hypothesis presented here helps to resolve outstanding nomenclatural issues and provides a basis for examining character evolution within this diverse, desert-adapted clade.