Farrar, Donald , Nason, John .
Restricted migration in an intragametophytic selfing species—an analysis of genetic structure in Botrychium simplex at Grass Lake, California.
ABUNDANCE of fern spores in the upper atmosphere and spectacular examples of long-range species migration are well demonstrated, but so are narrowly circumscribed species distributions and examples of limitation to migration ability. In part, this discrepancy is due to requirement by many species for cross-fertilization and therefore temporal and spatial juxtaposition of spores and gametophytes arriving in new habitats. Botrychium species are well-known for intragametophytic selfing. Therefore migration of Botrychium species to suitable habitats should be limited only by spore dispersal. We studied the genetic composition of Botrychium simplex in Grass Lake, a large (1 X 3 KM) flat meadow created by infilling of a glacial lake near South Lake Tahoe in California where densities reach 100 plants per square meter. Spatial genetic structure analysis of 14 sample sites revealed highly significant positive genetic correlations among plants separated by distances of up to 100 m; clear evidence of restricted spore dispersal. Analysis of allele distribution showed maximum allele richness at the upstream end of the lake bed, the oldest infilled section, and minimum allele richness at the downstream end where some open water still remains. B. simplex sporophores are raised above the short meadow vegetation, yet, despite the huge number of spores dispersed annually, genetic patterns reflect highly localized migration.[c.e.:srb]
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1 - Iowa State University, Department of Botany, Ames, Iowa, 50011, USA
2 - Iowa State University, Department of Ecology, Evolution & Organismal Biology, 253 Bessey Hall, Ames, Iowa, 50011-1020, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 4:15 PM