Browsing by Subject "rbcL"

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    Origins of the endemic scaly tree ferns on the galápagos and Cocos Islands
    (International Journal of Plant Sciences, 2015-11-01) Kao, T; Pryer, KM; Turner, MD; White, RA; Korall, P
    © 2015 by The University of Chicago. All rights reserved. Premise of research. Successful long-distance dispersal is rarely observed in scaly tree ferns (Cyatheaceae). Nevertheless, recent molecular evidence has suggested that the four endemic scaly tree ferns on the Galápagos Archipelago (Cyathea weatherbyana) and Cocos Island (Cyathea alfonsiana, Cyathea nesiotica, and Cyathea notabilis), two oceanic island groups west of Central and northern South America, probably each originated from different mainland America ancestors. However, the phylogenetic relationships inferred among these endemics and their mainland relatives have been unclear. This study is aimed at better resolving the relationships and tracing the origins of these island endemics. Methodology. Five plastid regions from 35 Cyathea species were analyzed to reconstruct phylogenetic relationships using parsimony, likelihood, and Bayesian approaches. We also estimated divergence times of these species, and our chronogram was used to reconstruct their biogeographical range history. Pivotal results. Our well-resolved phylogenetic tree of Cyathea, which is in agreement with previous studies, shows that when the four Galápagos and Cocos endemics are included, they each belong to separate subclades. Our biogeographical study suggests that the four endemics originated from independent colonization events from mainland America and that there was no dispersal of Cyathea between the island groups. We reveal more detailed relationships among the endemics and their respective close mainland relatives; some of these relationships differ from previous studies. Our findings are corroborated by new morphological data from ongoing stem anatomy studies. Conclusions. The four scaly tree ferns endemic to the Galápagos and Cocos Islands each did indeed originate as independent colonization events from separate sources in mainland America, and their closest relatives are identified here.
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    Phylogenetic relationships of the enigmatic fern families Hymenophyllopsidaceae and Lophosoriaceae: Evidence from rbcL nucleotide sequences
    (Plant Systematics and Evolution, 1999-01-01) Wolf, PG; Sipes, SD; White, MR; Martines, ML; Pryer, KM; Smith, AR; Ueda, K
    Nucleotide sequences from rbcL were used to infer relationships of Lophosoriaceae and Hymenophyllopsidaceae. The phylogenetic positions of these two monotypic fern families have been debated, and neither group had been included in recent molecular systematic studies of ferns. Maximum parsimony analysis of our data supported a sister relationship between Lophosoria and Dicksonia, and also between Hymenophyllopsis and Cyathea. Thus, both newly-examined families appear to be part of a previously characterized and well-supported clade of tree ferns. The inferred relationships of Lophosoria are consistent with most (but not all) recent treatments. However, Hymenophyllopsis includes only small delicate plants superficially similar to filmy ferns (Hymenophyllaceae), very different from the large arborescent taxa. Nevertheless, some synapomorphic characteristics are shared with the tree fern clade. Further studies on gametophytes of Hymenophyllopsis are needed to test these hypotheses of relationship.
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    Phylogeny of Marsileaceous Ferns and Relationships of the Fossil Hydropteris pinnata Reconsidered.
    (International journal of plant sciences, 1999-09) Pryer, KM
    Recent phylogenetic studies have provided compelling evidence that confirms the once disputed hypothesis of monophyly for heterosporous leptosporangiate ferns (Marsileaceae and Salviniaceae). Hypotheses for relationships among the three genera of Marsileaceae (Marsilea, Regnellidium, and Pilularia), however, have continued to be in conflict. The phylogeny of Marsileaceae is investigated here using information from morphology and rbcL sequence data. In addition, relationships among all heterosporous ferns, including the whole-plant fossil Hydropteris pinnata are reconsidered. Data sets of 71 morphological and 1239 rbcL characters for 23 leptosporangiate ferns, including eight heterosporous ingroup taxa and 15 homosporous outgroup taxa, were subjected to maximum parsimony analysis. Morphological analyses were carried out both with and without the fossil Hydropteris, and it was excluded from all analyses with rbcL data. An annotated list of the 71 morphological characters is provided in the appendix. For comparative purposes, the Rothwell and Stockey (1994) data set was also reanalyzed here. The best estimate of phylogenetic relationships for Marsileaceae in all analyses is that Pilularia and Regnellidium are sister taxa and Marsilea is sister to that clade. Morphological synapomorphies for various nodes are discussed. Analyses that included Hydropteris resulted in two most-parsimonious trees that differ only in the placement of the fossil. One topology is identical to the relationship found by Rothwell and Stockey (1994), placing the fossil sister to the Azolla plus Salvinia clade. The alternative topology places Hydropteris as the most basal member of the heterosporous fern clade. Equivocal interpretations for character evolution in heterosporous ferns are discussed in the context of these two most-parsimonious trees. Because of the observed degree of character ambiguity, the phylogenetic placement of Hydropteris is best viewed as unresolved, and recognition of the suborder Hydropteridineae, as circumscribed by Rothwell and Stockey (1994), is regarded as premature. The two competing hypotheses of relationships for heterosporous ferns are also compared with the known temporal distribution of relevant taxa. Stratigraphic fit of the phylogenetic estimates is measured by using the Stratigraphic Consistency Index and by comparison with minimum divergence times.
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    rbcL data reveal two monophyletic groups of filmy ferns (Filicopsida: Hymenophyllaceae).
    (American journal of botany, 2001-06) Pryer, KM; Smith, AR; Hunt, JS; Dubuisson, JY
    The "filmy fern" family, Hymenophyllaceae, is traditionally partitioned into two principal genera, Trichomanes s.l. (sensu lato) and Hymenophyllum s.l., based upon sorus shape characters. This basic split in the family has been widely debated this past century and hence was evaluated here by using rbcL nucleotide sequence data in a phylogenetic study of 26 filmy ferns and nine outgroup taxa. Our results confirm the monophyly of the family and provide robust support for two monophyletic groups that correspond to the two classical genera. In addition, we show that some taxa of uncertain affinity, such as the monotypic genera Cardiomanes and Serpyllopsis, and at least one species of Microtrichomanes, are convincingly included within Hymenophyllum s.l. The tubular- or conical-based sorus that typifies Trichomanes s.l. and Cardiomanes, the most basal member of Hymenophyllum s.l., is a plesiomorphic character state for the family. Tubular-based sori occurring in other members of Hymenophyllum s.l. are most likely derived independently and more than one time. While rbcL data are able to provide a well-supported phylogenetic estimate within Trichomanes s.l., they are inadequate for resolving relationships within Hymenophyllum s.l., which will require data from additional sources. This disparity in resolution reflects differential rates of evolution for rbcL within Hymenophyllaceae.
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    rbcL phylogeny of the fern genus Trichomanes (Hymenophyllaceae), with special reference to Neotropical taxa
    (International Journal of Plant Sciences, 2003-01-01) Dubuisson, JY; Hennequin, S; Douzery, EJP; Cranfill, RB; Smith, AR; Pryer, KM
    In order to estimate evolutionary relationships within the filmy fern genus Trichomanes (Hymenophyllaceae), we performed a phylogenetic analysis using rbcL nucleotide data from 46 species of Trichomanes belonging to all four of C. V. Morton's subgenera: Achomanes, Didymoglossum, Pachychaetum, and Trichomanes. Outgroups included four species of Hymenophyllum in three different subgenera, plus the monotypic genus Cardiomanes, from New Zealand. We find high resolution and robust support at most nodes, regardless of the phylogenetic optimization criterion used (maximum parsimony or maximum likelihood). Two species belonging to Morton's Asiatic sections Callistopteris and Cephalomanes are in unresolved basal positions within Trichomanes s.l., suggesting that rbcL data alone are inadequate for estimating the earliest cladogenetic events. Out of the four Morton trichomanoid subgenera, only subg. Didymoglossum appears monophyletic. Other noteworthy results include the following: (1) lianescent sect. Lacostea is more closely related to sect. Davalliopsis (traditionally placed in subg. Pachychaetum) than to other members of subg. Achomanes; (2) sections Davalliopsis and Lacostea, together with species of the morphologically different subg. Achomanes, make up a strongly supported Neotropical clade; (3) all hemiepiphytes (but not true lianas) and strictly epiphytic or epipetric species (Morton's subgenera Trichomanes and Didymoglossum) group together in an ecologically definable clade that also includes the terrestrial sect. Nesopteris; and (4) sect. Lacosteopsis (sensu Morton) is polyphyletic and comprises two distantly related clades: large hemiepiphytic climbers and small strictly epiphytic/epipetric taxa. Each of these associations is somewhat unexpected but is supported by cytological, geographical, and/or ecological evidence. We conclude that many morphological characters traditionally used for delimiting groups within Trichomanes are, in part, plesiomorphic or homoplastic. Additionally, we discuss probable multiple origins of Neotropical Trichomanes.
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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.