Frye, Christopher , Campbell, Christopher S. , Burgess, Michael B. .
Insights into morphological, molecular and life-history characterization of diploid Amelanchier canadensis (Rosaceae).
The interplay of hybridization, polyploidy, and apomixis creates taxonomic complexity in Amelanchier. Key to unraveling this complexity is the study of sexual diploid species from which polyploid apomicts have evolved. Here we examine morphological, molecular, and life-history characters of a group of diploid taxa occurring in eastern North America. Amelanchier canadensis var. canadensis is a common shrub in wetland habitats mostly in coastal areas in eastern North America. It is often sympatric with A. canadensis var. obovalis, a rhizomatous shrub of low pinelands and sandy soils on the Atlantic Coastal Plain. Amelanchier “ashei” is an informally named taxon of a rhizomatous shrub on ancient bedrock terraces and scoured rock outcrops along the Potomac River Gorge in Maryland and Virginia. Most previous determinations of ploidy in A. canadensis were tetraploid, with one report of diploidy in var. canadensis and one in var. obovalis. Ploidy level was unknown in A. “ashei.” Flow cytometry documented multiple occurrences of diploidy in each of these three taxa. These three taxa are closely related to one another morphologically and genetically. Amelanchier “ashei” differs in some morphological characters, an earlier flowering phenology, and its different habitat. Sequences from two loci of the granule bound starch synthase I gene show that these three diploid taxa are very closely related to one another. Fruit set in A. ‘ashei’ has been observed to be very low, with isolated individuals setting no fruit, suggesting self-incompatibility. Sexual A. bartramiana and sexual diploids in Crataegus are self-incompatible. Reproductive mode (sexual or apomictic) needs to be assayed for A. canadensis and A. “ashei.” Studies of this group of diploids and others will enhance our understanding of speciation in the genus and provide an important context for diversification involving apomixis and polyploidy.
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1 - Maryland Department of Natural Resources, Natural Heritage Program, 909 Wye Mills Road, Wye Mills, MD, 21679, USA
2 - University of Maine, School of Biology and Ecology, Orono, ME, 04469-5735, USA
3 - University of Maine, School of Biology & Ecology, Orono, ME, 04469-5735, USA
granule bound starch synthase I.
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Alpine C/Snowbird Center
Date: Monday, July 27th, 2009
Time: 8:30 AM