Pollination Strategy as an Evolutionary Response to Changing Climate in Erythranthe cardinalis
Loading...
Date
2024
Authors
Wilborn-Pilotte, Olivia
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Anthropogenic climate change has resulted in severe and prolonged periods of drought in the Western United States. Numerous studies have demonstrated plants' ability to adapt to this stress by altering their morphology, physiology, and phenology. Floral traits that influence a species' capacity for outcrossing or self-pollination are also likely to adapt to rapid environmental change. However, the extent to which drought will impact floral traits across the entire range of a species is unclear. Outcrossing demands more energy to develop pollinator-attractive traits but enhances genetic diversity while selfing conserves energy but results in genetically homogeneous populations. To understand the evolutionary trade-offs that exist for both outcrossing and selfing, we require further research across species' entire ranges. This study investigates how floral traits associated with selfing and outcrossing change across spatiotemporal gradients in Erythranthe cardinalis, which spans a latitudinal gradient across California and Oregon. Utilizing a resurrection approach, seeds were collected from three regions along the range of E. cardinalis (north, central, and south) before (2010) and after (2017) a period of sustained drought. Following a refresher generation, seedlings from each region and year were transplanted into a common garden in the northern region. To quantify the evolutionary tendency towards selfing versus outcrossing, we measured nectar volume, nectar sugar content, and anther stigma distance (ASD) in a subset of flowers from each region and year. Half of the sampled flowers were bagged at the bud stage and fecundity was estimated for bagged fruits following plant senescence. I hypothesized that plants under greater drought stress would exhibit floral traits associated with selfing to conserve energy and ensure reproduction. I also hypothesized that plants that exhibit traits associated with selfing would have higher fecundity under obligately selfing conditions. Our response variables yielded mixed results, with some indicating a tendency to outcross in the north and others in the south. Fecundity was highest in plants from the central region. Differences in trait values were significantly impacted by region, suggesting the importance of local climate variables in selecting floral traits. Overall, our findings highlight that different populations may be developing unique adaptations in floral traits related to pollination strategy in response to increasingly severe drought conditions. Future research should explore how these shifts in floral traits affect fitness and their potential to rescue drought-stressed populations.
Description
Keywords
Evolution, Adaptation, Pollination, Drought, Resurrection