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The Evolution of Self-Pollination in Granite Outcrop Species of Arenaria (Caryophyllaceae) V. Artificial Crosses Within and Between Populations

1990; American Society of Plant Taxonomists; Volume: 15; Issue: 3 Linguagem: Inglês

10.2307/2419349

1548-2324

Robert Wyatt,

Plant Diversity and Evolution

Experimental crosses performed within nine populations of Arenaria from granite outcrops in the southeastern United States revealed that all populations are self-compatible. Cross- pollinations performed in all possible pairwise combinations of the nine populations showed a wide range of crossability from 0-100% fruit-set. There was a statistically significant negative cor- relation between geographical distance separating pairs of populations and their crossability (r = -0.405; P < 0.01). Crossability mapping revealed two major groups of populations: 1) sites 6-9 from northeastern Georgia and the Carolinas and 2) sites 2,4, and 5 from Alabama, western Georgia, and the Atlanta area. These results, therefore, do not support the view that small-flowered popu- lations in Alabama and the Carolinas, previously distinguished as A. alabamensis, are distinct from large-flowered A. uniflora. Instead, it appears that small-flowered populations originated indepen- dently at least twice at the margins of the range and that these plants are more interfertile with their geographical neighbors, regardless of floral morphology.