| Abstrakt: |
Mating displays can incur costs in stressful environments. We examined whether males from artificial- selection lines differing in floral display (many vs. few flowers) responded differently to stress in the sexually dimorphic dioecious plant Silene latifolia. Males produce more flowers than females, presumably as a consequence of sexual selection for large floral displays. However, ecophysiological traits are genetically correlated with flower production, which may negatively affect many-flower-producing males under stressful conditions. To test this premise, we varied water and nutrients and measured flower production, petal size, and pollen production in males. We also measured ovule production in females. Most male traits responded negatively to one or both of the stress treatments. Under high nutrients, pollen production per plant was higher in the many-flower than in the few-flower line, whereas under low nutrients the reverse was true, leading to a significant interaction effect. Moreover, the reduction in pollen production per flower caused by stress was greater than the reduction in ovule production per flower~ but only in the many-flower line. Our results show that pollen production for the two selection lines is differently plastic, which may lead to among-population differences in both trait means and sexual dimorphism. [ABSTRACT FROM AUTHOR] |
