Systematics of Eastern North American Bracken Fern

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dc.contributor.authorSpeer, William D.en
dc.contributor.committeechairHilu, Khidir W.en
dc.contributor.committeememberTurner, Bruce J.en
dc.contributor.committeememberPorter, Duncan M.en
dc.contributor.departmentBiologyen
dc.date.accessioned2014-03-14T20:51:33Zen
dc.date.adate1997-05-07en
dc.date.available2014-03-14T20:51:33Zen
dc.date.issued1997-05-07en
dc.date.rdate1998-05-07en
dc.date.sdate1998-07-21en
dc.description.abstractThe cosmopolitan Pteridium aquilinum (L.) Kuhn is widespread throughout eastern North American, where it is represented primarily by Tryon's (1941) var. latiusculum (Desv.) Underw. and var. pseudocaudatum (Clute) Heller. The taxonomy of Pteridium is controversial. Fourteen isozyme loci and 12 morphological characters were used to assess the taxonomic relationship of these two varieties. Isozyme data indicated a high mean genetic identity (I = 0.976) between eleven bracken populations. Strong patterns of geographic variation for isozyme allele frequencies were also observed. The isozyme results did not separate the two taxa. Numerical analysis of the morphology distinguished the two taxa when the qualitative characters were used alone or in conjunction with some of the quantitative traits. All qualitative characters differed significantly between the two taxa. No perceptible geographic pattern of variation was observed. Morphological distinctiveness was maintained even in those localities where both taxa were present, with few or no intermediates being found. Isozyme evidence suggestive of gene flow between the two varieties was found at Greensboro, NC, where the two morphotypes were easily recognizable. The isozyme evidence strongly indicates conspecificity, while the morphological evidence supports their status at the varietal level.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-4320112349751421en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-4320112349751421/en
dc.identifier.urihttp://hdl.handle.net/10919/36715en
dc.publisherVirginia Techen
dc.relation.haspartetd.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectplant systematicsen
dc.subjectallozymeen
dc.subjectpteridophyteen
dc.subjectunivariate analysisen
dc.subjectmultivariate analysisen
dc.subjectclinal variationen
dc.titleSystematics of Eastern North American Bracken Fernen
dc.typeThesisen
thesis.degree.disciplineBiologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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