Browsing by Subject "EXTANT FERNS"
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Item Open Access Phylogeny and divergence time estimates for the fern genus Azolla (Salviniaceae)(International Journal of Plant Sciences, 2007-10-22) Metzgar, JS; Schneider, H; Pryer, KMA phylogeny for all extant species of the heterosporous fern genus Azolla is presented here based on more than 5000 base pairs of DNA sequence data from six plastid loci (rbcL, atpB, rps4, trnL-trnF, trnG-trnR, and rps4-trnS). Our results are in agreement with other recent molecular phylogenetic hypotheses that support the monophyly of sections Azolla and Rhizosperma and the proposed relationships within section Azolla. Divergence times are estimated within Azolla using a penalized likelihood approach, integrating data from fossils and DNA sequences. Penalized likelihood analyses estimate a divergence time of 50.7 Ma (Eocene) for the split between sections Azolla and Rhizosperma, 32.5 Ma (Oligocene) for the divergence of Azolla nilotica from A. pinnata within section Rhizosperma, and 16.3 Ma (Miocene) for the divergence of the two lineages within section Azolla (the A. filiculoides + A. rubra lineage from the A. caroliniana + A. microphylla + A. mexicana complex). © 2007 by The University of Chicago. All rights reserved.Item Open Access Phylogeny and relationships of the neotropical Adiantum raddianum group (Pteridaceae)(Taxon, 2016-12-01) Hirai, RY; Schuettpelz, E; Huiet, L; Pryer, KM; Smith, AR; Prado, J© International Association for Plant Taxonomy (IAPT) 2016. With more than 200 species, the maidenhair fern genus Adiantum is among the top ten most diverse fern genera. Adiantum is pantropical in distribution and, due to the presence of a unique synapomorphy (sporangia borne on indusia rather than laminae), perhaps the most easily recognized fern genus. Many of its members, including numerous cultivars derived from A. raddianum, are grown as ornamentals. Because of its size, a comprehensive taxonomic study of Adiantum is difficult and the genus is perhaps better approached through a series of narrower studies. Here, we focus specifically on A. raddianum and putative allies. We find a newly defined A. raddianum group to be strongly supported as monophyletic and segregated from other maidenhair ferns on the basis of genetic as well as morphological characteristics. Bayesian inference and maximum likelihood analyses of plastid atpA, chlL, chlN, rbcL, and rpoA sequences support the A raddianum clade as sister to A poiretii and its allies. We identify round-reniform indusia to be a characteristic of the A.raddianum group (vs. lunate in the A.poiretii group). Additionally, we find species in the Apoiretii group to differ in having a unique 66 nucleotide deletion in our chlN gene alignment. The neotropical Araddianum group comprises at least 17 species (14 studied here), some widely distributed; one was recently described (A. alan-smithii).Item Open Access Plastid atpA data provide improved support for deep relationships among ferns(Taxon, 2006-01-01) Schuettpelz, E; Korall, P; Pryer, KMDNA sequence data and phylogenetic approaches have contributed greatly to our understanding of fern relationships. Nonetheless, the datasets analyzed to date have not been sufficient to definitively resolve all parts of the global fern phylogeny; additional data and more extensive sampling are necessary. Here, we explore the phylogenetic utility of the plastid atpA gene. Using newly designed primers, we obtained atpA sequences for 52 fern and 6 outgroup taxa, and then evaluated the capabilities of atpA relative to four other molecular markers, as well as the contributions of atpA in combined analyses. The five single-gene datasets differed markedly in the number of variable characters they possessed; and although the relationships resolved in analyses of these datasets were largely congruent, the robustness of the hypotheses varied considerably. The atpA dataset had more variable characters and resulted in a more robustly supported phylogeny than any of the other single gene datasets examined, suggesting that atpA will be exceptionally useful in more extensive studies of fern phylogeny and perhaps also in studies of other plant lineages. When the atpA data were analyzed in combination with the other four markers, an especially robust hypothesis of fern relationships emerged. With the addition of the atpA data, support increased substantially at several nodes; three nodes, which were not well-supported previously, received both good posterior probability and good bootstrap support in the combined 5-gene (> 6 kb) analyses.