Campbell, Christopher , Burgess, Michael B. , Frye, Christopher .
Microspecies problems in Amelanchier (Rosaceae).
In Amelanchier, hybridization creates novel forms that may be perpetuated by apomixis. Such forms may persist, disperse widely, and be generally recognized as species, such as the allotetraploid apomict A. laevis. DNA sequences from the granule bound starch synthase I (GBSSI) gene indicate that one of the ancestors of A. laevis is closely related to the diploid, sexual shrub, A. bartramiana, and the other comes from a clade of taxa that, like A. laevis, can be trees. Another allotetraploid apomict, informally named A. “erecta”, is a microspecies that has not been formally described because it is locally distributed in Maine plus one site in Quebec. The informally named tetraploid, A. “rubra”, which is also mostly limited to a narrow range in Maine, contributes to additional potential microspecies when it hybridizes with A. bartramiana and A. laevis. Another challenge from microspecies is morphological similarity to widespread Amelanchier diploids. Numerous tetraploids, including known apomicts, are morphologically close to the widespread diploid A. canadensis. GBSSI sequences of one of these tetraploids support allotetraploidy, with one of the putative parents being diploid A. canadensis and the other being distantly related to A. canadensis. A similar pattern occurs in A. arborea, which is diploid over much of eastern North America. Numerous tetraploid individuals resemble diploid A. arborea in some but not all aspects of habit, leaves, and flowers. GBSSI and cpDNA data suggest that a tetraploid, A. arboreaÂ¬like plant is an allotetraploid with diploid A. arborea as one of the parents. Morphological convergence has apparently occurred in a Maine plant that is morphologically similar to diploid A. humilis but grows over two hundred miles outside the range of this species. This Maine plant is not closely related to A. humilis on GBSSI trees. Microspecies thus confound the taxonomy of this genus.
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Amelanchier web page
1 - University of Maine, School of Biology & Ecology, Orono, ME, 04469-5735, USA
2 - Maryland Department of Natural Resources, Natural Heritage Program, 909 Wye Mills Road, Wye Mills, MD, 21679, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood D/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 2:30 PM