Cushman, Kevin , Burgess, Michael , Doucette, Eric , Frye, Christopher , Campbell, Christopher .
Characterizing the spicata complex, a group of allotetraploid apomicts in Amelanchier (Roasaceae).
We use species complexes to classify taxonomic diversity of numerous polyploid apomicts in Amelanchier. Unlike most species complexes in the genus, the spicata complex does not include diploids. Instead, 84 individuals for which we have cytometrically flow determined ploidy are tetraploid,and 15 individuals for which we have molecular data are allopolyploid. Amelanchier spicata (Lam.) K. Koch, the dwarf or running shadbush, is morphologically cohesive from northern Michigan to North Carolina and into eastern Canada. Sequence data from ETS, ITS, and a LEAFY gene show A. spicata to be a consistent hybrid of three diploids: A.humilis Wiegand, A. bartramiana (Tausch)M. Roemer, and A. canadensis (L.)Medic. The Nantucket shadbush (A.nantucketensis Bickn.) grows in isolated pockets from South Carolina to Maine and in Nova Scotia. It differs from A.spicata in fewer teeth below the mid-point on mature leaves and andropetaly (the occurrence of microsporangia on tiny petals). Molecular evidence indicates that A. nantucketensis is a hybrid between A. canadensis and A. humilis. Numerous other entities are similar to A. spicata and A.nantucketensis in habit, leaf size, pubescence, and teeth at the apex, but also differ morphologically. Some plants from Maine, for example, were considered to be A. spicata by Dibble et al. (1998) but are hybrids with A. laevis Wiegand. We recognize A. "maritima" informally because it is a microspecies restricted to the Atlantic Coast from northern Massachusetts to central Maine. Molecular data show that ancestry of A. "maritima" is similar to that of A. nantucketensis, but morphologically, it resembles A. spicata and exceeds both taxa in the size of floral characteristics. Thus the spicata complex includes formally and informally recognized taxa and provides a name for a heterogeneous, but morphologically distinguishable assemblage.
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Presentation Type: Oral Paper:Papers for Sections
Location: Delaware D/Hyatt
Date: Wednesday, July 11th, 2012
Time: 9:30 AM