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Abstract Detail


Systematics/Phytogeography / Taxonomie/ Section

Burgess, Michael B. [1], Campbell, Christopher S. [1].

Evolutionary complexity of Amelanchier sanguinea (Rosaceae) and related taxa.

Amelanchier sanguinea, the red-twigged shadbush, is one of the older names in the genus and has been recognized in all major treatments of North American Amelanchier. Two species, A. amabilis and A. gaspensis, were first published as subspecific taxa of A. sanguinea and later elevated to species. Neither species have been universally recognized, and both are narrowly distributed, A. amabilis from central New York to southern Ontario and Québec and A. gaspensis, as originally conceived, to the Gaspé peninsula in Québec. Nuclear-encoded granule bound starch synthase I (GBSSI) sequences strongly link A. amabilis and A. cusickii, which grows in northwestern North America. These two species also share a potential synapomorphy of petals that are often more than 2 cm in length, the longest in North America. Amelanchier amabilis and A. cusickii are, however, widely separated on trees based on several cpDNA regions, suggesting genetic exchanges with other taxa in the ancestry of one or both species. The nature of A. gaspensis has been clouded by the fact that it was named and elevated to species status without adequate flowering material. Previous results showed that A. gaspensis is biphyletic, with ITS repeats representing two divergent clades, one containing all sampled western North American species plus A. humilis and A. sanguinea from eastern North America (ITS clade A), and the other with all remaining sampled eastern North American species (ITS clade B). Most representatives of clade A form a strongly supported clade in GBSSI trees, and this clade includes two A. gaspensis clones. We expect to find GBSSI A. gaspensis clones representing ITS clade B, as we have with another biplyletic taxon in the genus. The evolutionary complexity implicit in these preliminary results is not surprising in a group in which apomixis, polyploidy, and hybridization are common.


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Related Links:
Amelanchier Systematics and Evolution


1 - University of Maine, Dept. of Biological Sciences, 5735 Hitchner Hall, Orono, ME, 04469, United States

Keywords:
cpDNA
granule bound starch synthase I
hybridization.

Presentation Type: Oral Paper:Papers for Sections
Session: 46
Location: 169/Law
Date: Tuesday, July 29th, 2008
Time: 2:30 PM
Number: 46007
Abstract ID:768


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