Publication in: Spring 2023 Issue

Comparison of Seed Traits between Two Sarracenia Species and their Hybrids
Alyssa Lynch
Faculty Mentor(s):
Caroline Kennedy
Abstract / Summary:
Two western North Carolina native species of pitcher plants, Sarracenia jonesii Wherry and Sarracenia purpurea var. montana Schnell and Determan, co-occur in mountain bogs and seeps. Both are currently of conservation concern, with S. jonesii declared as federally endangered and S. purpurea var. montana as a federal species of concern. These species are experiencing population declines due to habitat loss, and they also readily hybridize when in sympatry. Hybridization is a conservation concern among these two species because of the possibility of hybrids outcompeting their parental species and the potential loss of genetically distinct gene pools through introgression. In late summer 2022, seeds from the two parental taxa and their hybrids were collected from a western North Carolina site. A subset of seeds were weighed, and seed viability was determined using a triphenyl tetrazolium chloride assay. Seeds were germinated in the lab with exposure to natural sunlight from the window at 30°C and 80),, humidity, and checked for radicle emergence every two days for 46 days. Seeds were also germinated at the field site in both Sphagnum peat moss and seed bags. Generalized linear models were used to determine if there were significant differences in seed size, seed viability, or germination rates among the three plant types. Sarracenia jonesii had significantly lower percent seed germination than both Sarracenia purpurea var. montana and hybrids, and seed mass had a positive linear relationship with seed germination. Sarracenia purpurea var. montana had significantly higher pollen production, seed production, and amount germination compared to S. jonesii and hybrids.. Seed viability was not a reliable indicator of reproductive success in these taxa. Reproductive effort was investigated in earlier studies using pollen production and floral overlap. This study complements preliminary seed production data for reproductive output with seed size, viability, and germination rates to obtain a more complete understanding of the current reproductive status of S. jonesii, S. purpurea var. montana and their hybrids at this site. Future conservation efforts should prioritize continuous population monitoring to understand the population trend over time and observe for potential evolutionary consequences of hybridization.
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