Ecological genetics of floral longevity in Campanula rotundifolia, the alpine harebell

Floral longevity, the time between corolla opening and senescence, is the time available for fitness accrual through male and female function on a per flower basis. This study employs manipulative approaches in the field to explore variation in floral longevity at a geographical scale. A common garden greenhouse study is used to determine the genetic component of variation in floral longevity. Campanula rotundifolia (Campanulaceae), an herbaceous perennial species ranging from montane to alpine habitats in the Colorado Rocky Mountains was used as the study system.; In the absence of pollinators, staminate longevity was significantly greater in montane than alpine flowers in both the field and the greenhouse. Staminate longevity in C. rotundifolia appears adapted to local pollen removal schedules. The lack of pollen limited seed set at the montane site suggested that extended staminate longevity there might result from competition among flowers for pollen export opportunities.; Pistillate longevity in the field was significantly shorter in montane than alpine flowers in the presence and absence of pollinators. Increased pollen deposition rates significantly shortened pistillate longevity at both sites. Extended pistillate longevity was adaptive at the alpine site under low but constant pollen deposition rates. When pollen deposition was delayed for three days, montane and alpine flowers experienced a significant fecundity cost relative to open-pollinated flowers. Consequently, a sit and wait strategy in regards to pollen deposition can be maladaptive in some contexts.; Greenhouse studies indicated that staminate longevity in C. rotundifolia is regulated through local adaptation, and that pistillate longevity is regulated by a plastic response to site-specific pollen deposition rates. These results challenge a previous floral longevity model prediction that fitness accrual rates of both genders determine floral longevity.; My data demonstrate that delayed pollen deposition together with increased floral maintenance costs can result in reduced fecundity, even under alpine conditions. If predictions of pollinator declines and global warming are accurate, then the persistence of some plant species may not be ensured by migration to higher altitudes.