Does optimal packing of flowers in syconia shape style length variation in monoecious figs?

Abstract

Style length variation in female flowers of monoecious figs has been shown to play an important role in regulating the proportion of flowers that develop into seeds and those that become infested by the pollinator wasp. In this study, we tested the suggestion that style length variation in figs is a consequence of optimal packing of the flowers. We show that optimal packing of flowers in fig syconia will result in a highly skewed distribution of style lengths and a positive skewness of pedicel lengths. These predictions were qualitatively tested in eight species of figs and the results indicate that observed style length distributions did not conform to those expected. We argue that while the pedicel lengths are likely to be a spinoff of optimal packing of the flowers, style lengths are probably shaped by independent selective fotces. The pedicel lengths also are subjected to compensatory growth so as to place the stigmas at a common height in the central cavity for effective pollination of the flowers. This was substantiated by the response (dependence) of pedicels to (on) the length of the style, neck, and other floral features. In all species the coefficient of variation of styles was very consistent (ca 30 %). This is in accordance with expectations if style lengths are shaped to regulate the proportion of flowers for wasp and seed production.