Doucette, Eric , Burgess, Michael , Cushman, Kevin , Frye, Christopher , Campbell, Christopher .
What is Amelanchier laevis?
Amelanchier laevis Wieg. as currently circumscribed occurs from northern Georgia to Newfoundland and west to the Great Lakes ecoregion. This species is part of a clade with A. arborea (Michx. f.) Fern. and A. canadensis (L.) Medik. that is strongly supported by DNA sequence data. Members of this clade have many flowered elongate inflorescences, normally glabrous ovary summits, and (at least in some individuals) an arborescent habit. Amelanchier laevis is morphologically diagnosable by the character suite of anthocyanic and glabrescent emerging foliage, long petals, and long lowest pedicel. Our fieldwork revealed diploid and tetraploid individuals conforming to this morphology. The diploid form, which we refer to as diploid A. laevis, occurs only at higher elevations in the southern Appalachians, with polyploids occupying the remainder of the sampled range. Based on the location of the type specimen (Massachusetts), Wiegand described the polyploid taxon. In phylogenetic trees based on nuclear regions ETS and ITS, some clones of all our tetraploid A. laevis individuals are linked to diploid A. laevis, and other clones, depending upon the individual plant, nest with A. canadensis or have unresolved relationships with other clade B members. These trees suggest that tetraploid A. laevis is an assemblage of genetically heterogeneous allotetraploids of multiple origins whose ancestry is wholly within clade B. Morphologically, A. laevis is closest to A. arborea, and hybrids between them can be difficult to detect. Hence, ETS sequences revealed a southern Appalachian diploid to be a morphologically cryptic hybrid between these two species. Inflorescence and leaf characters may separate the two ploidy levels, although this potential difference needs to be assessed with greater sampling. We plan to obtain additional samples to explore the relationship between the two ploidy levels with A. laevis morphology and to investigate the taxonomic status of the diploid.
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1 - University Of Maine, Department Of Biological Sciences, 261 HITCHNER HALL, ORONO, ME, 04469-5735, USA
2 - University of Pennsylvania, USA
3 - P.O. Box 143, Levant, ME, 04456, USA
4 - Maryland Wildlife And Heritage Service, 909 Wye Mills Road, PO Box 68, Wye Mills, MD, 21679, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell A/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 2:30 PM