Pollination and abiotic stress alter the distribution of variation in floral longevity and opportunities for adaptation

Background and aims: Floral longevity is thought to evolve by natural selection imposed by pollinators on heritable variation and resource constraints. In species with pollination-induced wilting, pollination rates should also influence phenotypic expression of genetic variation in longevity, raising questions of how and when variation in floral lifespan is shaped by adaptation. Methods: We experimentally manipulated pollination rates in a wild population of Sabatia angularis (Gentianaceae). We asked how treatments influenced pollen gain curves, the phenotypic distribution of floral longevity, trait correlations, and potential costs. We further asked how abiotic factors influence longevity and how they may interact with pollination conditions. Key results: Mean, variance, and maximum of longevity expressed increased with declining pollination. A flower longevity-number trade-off and positive longevity-flower size relationship persisted regardless of pollination context. Plants with more, not longer-lived, flowers suffered greater seed predation, potentially mitigating the flower number-longevity trade-off. The vapor pressure deficit (VPD) and seasonal changes constrained longevity. VPD had the strongest effect under the poorest pollination conditions, where longer-lived flowers would otherwise be favored. Conclusions: Our findings highlight how ecological conditions and internal constraints shape phenotypic variation. Conditional expression of longevity may preserve genetic variation, enabling rapid evolutionary responses when environmental change causes selection and exposure of variation to align.