Effects of apomixis and polyploidy on diversification and geographic distribution in Amelanchier (Rosaceae).

Autor: Burgess MB; Department of Biological Sciences, State University of New York, Plattsburgh, Plattsburgh, New York 12901 USA., Cushman KR; School of Biology and Ecology, University of Maine, Orono, Maine 04469 USA., Doucette ET; School of Biology and Ecology, University of Maine, Orono, Maine 04469 USA., Talent N; Royal Ontario Museum, Department of Natural History, 100 Queen's Park, Toronto, M5S 2C6, Canada., Frye CT; Maryland Department of Natural Resources, Natural Heritage Program, 909 Wye Mills Road, Wye Mills, Maryland 21679 USA., Campbell CS; School of Biology and Ecology, University of Maine, Orono, Maine 04469 USA.
Jazyk: angličtina
Zdroj: American journal of botany [Am J Bot] 2014 Aug; Vol. 101 (8), pp. 1375-87.
DOI: 10.3732/ajb.1400113
Abstrakt: Unlabelled: •
Premise of the Study: Amelanchier polyploid apomicts differ from sexual diploids in their more complex diversification, greater species problems, and geographic distribution. To understand these differences, we investigated the occurrence of polyploidy and frequency of apomixis. This research helps clarify species delimitation in an evolutionarily complex genus.•
Methods: We used flow cytometry to estimate genome size of 1355 plants. We estimated the frequency of apomixis from flow-cytometrically determined ploidy levels of embryo and endosperm and from a progeny study using RAPD markers. We explored relationships of triploids to other ploidy levels and of ploidy levels to latitude plus elevation.•
Key Results: Diploids (32% of sample) and tetraploids (62%) were widespread. Triploids (6%) mostly occurred in small numbers with diploids from two or more species or with diploids and tetraploids. Seeds from diploids were 2% apomictic, the first report of apomixis in Amelanchier diploids. Seeds from triploids were 75% apomictic. We documented potential triploid bridge and triploid block from unbalanced endosperm and low pollen viability. Seeds from tetraploids were 97% apomictic, and tetraploids often formed microspecies. We did not find strong evidence for geographical parthenogenesis in North American Amelanchier. Most currently recognized species contained multiple ploidy levels that were morphologically semicryptic.•
Conclusions: Documentation of numerous transitions from diploidy to polyploidy helps clarify diversification, geographic distribution, and the species problem in Amelanchier. Despite the infrequent occurrence of triploids, their retention of 25% sexuality and capacity for triploid bridge may be important steps between sexual diploids and predominantly apomictic tetraploids.
(© 2014 Botanical Society of America, Inc.)
Databáze: MEDLINE
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