Hawkins, Angela , Archambeault, Alan , Cannon, Brandi , Faust, Amber , Levsen, Nicholas , Williams, Justin , Randle, Christopher .
Subspecific classification within Phoradendron serotinum (Viscaceae): Morphological and molecular markers for assessment of population genetic structure.
Phoradendron serotinum, (leafy mistletoe) is a hemi-parasitic plant of the family Viscaceae found in the United States and Mexico. P. serotinum is the only species in Phoradendron (234) that has been given subspecific classification. Subspecies macrophyllum, serotinum, and tomentosum occur in the eastern United States from southern New Jersey to southern Florida, through the Midwest south of Oklahoma and into Mexico, and on the west coast from Oregon to Baja California. Subspecies angustifolium grows in isolated regions of central Mexico. Subspecies are difficult to identify based on morphology alone. Identification of P. serotinum subspecies in eastern Texas is especially difficult as characters that are otherwise diagnostic of subspecies do not adequately separate three of the subspecies (macrophyllum, serotinum, and tomentosum) that overlap in this region. Molecular and morphometric analyses were utilized to resolve taxonomic confusion within P.serotinum and test the hypotheses that: 1) The four subspecies of P.serotinum represent separate cohesive genetic units and 2) The subspecies of P. serotinum share a single population of origin that is likely within the current distribution. It was predicted that the four subspecies of P. serotinum would not represent separate cohesive genetic units and that molecular data would provide justification needed to synonymize the subspecies as P. serotinum. It was further predicted that east Texas was the single center of origin for subspecies divergence. Morphometric measurements were recorded for nearly 200 vouchers that were analyzed from a majority of the growth range. Microsatellite loci were isolated and seven were amplified and scored for 95 individuals representing the growth range in its entirety. Results, both morphological and molecular, support the hypothesis that the four subspecies of P. serotinum represent separate cohesive genetic units. Further, molecular data support a single central location for subspecies divergence; however both morphological and molecular data equivocally support east Texas as the center of divergence while simultaneously supporting a population in the west as the center of origin.
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1 - Texas A & M University, Biological Sciences, Texas A&M University Dept. Of Biology, 3258 TAMUS, College Station, TX, 77843-3258, USA
2 - Sam Houston State University, Department of Biological Sciences, 1900 Avenue I, Huntsville, TX, 77340, USA
3 - Texas Tech University, Department Of Ecology & Evolutionary Biology, Department Of Biological Sciences, Lubbock, TX, 79409, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Portland Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 9:30 AM