You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Floral Display in Phlox and Geranium: Adaptive Aspects
Mary F. Willson, Linda J. Miller and Beverly J. Rathcke
Vol. 33, No. 1, Part 1 (Mar., 1979), pp. 52-63
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2407365
Page Count: 12
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Both Geranium maculatum and Phlox divaricata are self-compatible, the flowers lasting 4-6 days typically; geranium is protandrous. Large inflorescences produced more seeds, but the seed production per flower varied little with number of flowers per stem-decreasing slightly for geranium, and increasing slightly for phlox at one site. Very small numbers of flowers per stem had a higher probability of failing to make any seeds at all. The frequency distributions of number of flowers per stem and cluster size were both skewed toward the smaller sizes. The modal number of flowers per stem for phlox fell close to 'optima' predicted from the data on flowers per stem, cluster size, and seed production per flower in a model that maximized seed production per individual (or cluster). However, modal cluster sizes were much smaller than the predicted optima, probably because of environmental heterogeneity-microsite and temporal differences. No effect of between-plant distances on seed set was observed. We know of no other study that attempts to relate the entire floral display of plants to any index of fitness and present these preliminary results in hopes of stimulating more consideration of such matters.
Evolution © 1979 Society for the Study of Evolution