Precautionary hand pollination suggests outbreeding depression between potential seed donor populations for a rare wetland plant1
Abstract Pyrrocoma racemosa var. racemosa, is a rare, endemic species found in six remnant Willamette Valley wetland prairie sites in western Oregon, USA. Due to its rarity and association with high-quality wetland habitat, P. r. var. racemosa is a focal species for reintroduction and genetic rescue. However, no genetic studies for this species have been undertaken. I conducted a pollen addition experiment between the two largest P. racemosa populations to determine the effects of selfing, intrapopulation crosses and interpopulation crosses on plant fitness. An ANOVA indicated that the percentage of filled achenes from intrapopulation crosses was significantly greater (≈ 30% more filled achenes) than both interpopulation crossing and selfing, which did not statistically differ from each other. Pollen viability, inferred through flourescein diacetate staining, did not differ statistically over the time span that it took to gather and perform the pollen addition treatments, suggesting that the diminished se...