*Institut fur Systematische Botanik, Universität Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
Pollen flow, population composition, and the adaptive significance of distyly in Linum tenuifolium L. (Linaceae)
Article first published online: 14 JAN 2008
Biological Journal of the Linnean Society
Volume 25, Issue 3, pages 235–242, July 1985
How to Cite
NICHOLLS, M. S. (1985), Pollen flow, population composition, and the adaptive significance of distyly in Linum tenuifolium L. (Linaceae). Biological Journal of the Linnean Society, 25: 235–242. doi: 10.1111/j.1095-8312.1985.tb00395.x
- Issue published online: 14 JAN 2008
- Article first published online: 14 JAN 2008
- Accepted for publication October 1984
- Linum tenuifolium L.;
- heterostyly-pollen flow
The function of distyly as a device promoting inter-morph pollination was proposed by Darwin over a century ago, though only recently have experimental studies been undertaken to test this hypothesis. These studies are unrealistic since they assume regular spatial distribution of morphs within a population and fail to consider intra-flower pollination in assessing distyly's effects. Pollen flow in two populations of Linum tenuifolium L. was investigated using a fluorescent-dye marker technique. One population was dimorphic and self-incompatible; the other was monomorphic and self-compatible. In both populations pollen dispersal was leptokurtic with over 75% of grains detected within 5 m from the source. Intra-flower pollinations comprised a large proportion of individual stigma loads (42% for the dimorphic form; 49% for the monomorphic form). Total stigmatic loads for the dimorphic population showed equal proportions of pin and thrum pollen on both long-style and short-style stigmas, though variation in individual loads was marked. Values ranging from 34.2 to 61.5% legitimate pollen were recorded. The irregular distribution of morphs observed at the dimorphic site will reduce the efficiency of heterostyly as a device promoting intermorph pollination. The reduction in intra-flower pollination suggests adaptive significance of this floral dimorphism in increasing the efficiency of pollen dispersal to the individual.