Effects of Pollen Source and Abundance on Fitness of a Carnivorous Plant

Abstract

Plants with fragmented populations and those living in threatened habitats may require repatriation efforts to maintain healthy populations. Populations of Sarracenia alata, the pale pitcher plant, are severely fragmented, and the species is near threatened. A complete understanding of its reproduction will be crucial in establishing and maintaining healthy populations. The goals of this study were to determine 1) if S. alata is capable of selfing (reproducing with pollen from the same individual) and autogamy (selfing without pollen transfer by an outside source); 2) whether fitness differs between selfed and outcrossed plants; and 3) whether pollen load affects reproductive success. We used seed set to measure individual fitness. Thus, it was necessary to determine a reliable method of counting seeds. Two methods (DotDotGoose and Image J) were examined, and these gave statistically similar results. We found that while S. alata is capable of selfing, it is not autogamous. Seed set was significantly higher in outcrossed individuals than in selfed individuals. In 2019, supplemental pollen resulted in increased seed production compared to control and pollen restricted groups. During 2021, there was no significant difference between the number of seeds produced by control plants and those receiving supplemental pollen. This study demonstrates the important role of pollinators in maintaining healthy populations in this system.