Browsing by Subject "GENUS TRICHOMANES HYMENOPHYLLACEAE"

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    Divergence times and the evolution of epiphytism in filmy ferns (Hymenophyllaceae) revisited
    (International Journal of Plant Sciences, 2008-11-01) Hennequin, S; Schuettpelz, E; Pryer, KM; Ebihara, A; Dubuisson, J
    Although the phylogeny of the filmy fern family (Hymenophyllaceae) is rapidly coming into focus, much remains to be uncovered concerning the evolutionary history of this clade. In this study, we use two data sets (108-taxon rbcL+ rps4, 204-taxon rbcL) and fossil constraints to examine the diversification of filmy ferns and the evolution of their ecology within a temporal context. Our penalized likelihood analyses (with both data sets) indicate that the initial divergences within the Hymenophyllaceae (resulting in extant lineages) and those within one of the two major clades (trichomanoids) occurred in the early to middle Mesozoic. There was a considerable delay in the crown group diversification of the other major clade (hymenophylloids), which began to diversify only in the Cretaceous. Maximum likelihood and Bayesian character state reconstructions across the broadly sampled single-gene (rbcL) phylogeny do not allow us to unequivocally infer the ancestral habit for the family or for its two major clades. However, adding a second gene (rps4) with a more restricted taxon sampling results in a hypothesis in which filmy ferns were ancestrally terrestrial, with epiphytism having evolved several times independently during the Cretaceous. © 2008 by The University of Chicago. All rights reserved.
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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.