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Abstract Detail

Reproductive Processes

Meyer, Elena [1], Swift, Joel [2], Smith, Stacy [3], Bassuner, Burgund [4], Menges, Eric [5], Edwards, Christine [6].

The trajectory of the mating system and factors affecting selfing and outcrossing rates in an amphicarpic species with a mixed mating system, Polygala lewtonii.

Reproductive strategies of plants can range from fully selfing to fully outcrossing, but some are mixed, where individuals reproduce by a combination of selfing and outcrossing. Mixed mating has been hypothesized to be maintained as an adaptation to environmental instability, providing reproductive assurance regardless of whether cross-pollination is possible. However, it is debated whether mixed mating systems are evolutionarily stable, because selfers have an automatic transmission advantage that may lead to fixation of selfing unless inbreeding depression is high, in which case fixation of outcrossing is expected. Polygala†lewtonii is a species with a mixed mating system and three different flower types: belowground cleistogamous (CL) flowers, and both aboveground cleistogamous (CL) and chasmogamous (CH) flowers. It is also amphicarpic, meaning it produces both aboveground and belowground flowers and seeds, which serve different ecological roles. Previous research has shown that populations of P.†lewtonii have high inbreeding rates and fine-scale patterns of genetic structuring. In this study, we investigated the trajectory of the mating system and the factors affecting the relative proportion of reproduction by selfing and outcrossing in P. lewtonii. First, we investigated whether outcrossing is occurring in aboveground chasmogamous (CH) flowers by genotyping maternal individuals and their seeds. We also analyzed the effects of prescribed fire on genetic diversity, population structure and inbreeding/outcrossing rates by collecting and genotyping leaf samples from populations both pre- and post-fire. We found that most seeds produced by aboveground CH flowers were produced by either selfing or biparental inbreeding, indicating that despite showy flowers, there is either a lack of pollinators or pollinators are ineffective at transferring pollen between genetically different individuals. This species has high selfing rates and shows increases in population structure after a fire, suggesting that disturbance likely promotes germination of selfed seed produced in close proximity to its parent, possibly by an increase in germination of seeds produced by belowground CH flowers. Our results indicate that outcrossing occurs only sporadically and that several forces appear to be promoting the fixation of selfing in P. lewtonii. Future research will focus on analyzing the trends in the mating systems over time and measuring levels of inbreeding depression in P. lewtonii, which is expected to be low given the predominance of inbreeding in this species.

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1 - New College of Florida, Biology, 5800 Bay Shore Rd., Sarasota, FL, 34243, United States
2 - Saint Louis University, 2166 Lawrence St., APT 2N, St. Louis, MO, 63110, United States
3 - Archbold Biological Station, Plant Ecology Program, Archbold Biological Station , P.O. Box 2057, Lake Placid, FL , 33862
4 - Missouri Botanical Garden, Center for Conservation and Sustainable Development, Missouri Botanical Garden, St. Louis, MO, 63166, USA
5 - Archbold Biological Station, 123 Main Drive, Venus, Fl, 33960, United States
6 - Missouri Botanical Garden, PO Box 299, St. Louis, MO, 63166, United States

Polygala lewtonii
Plant Reproduction Biology
Ecological Disturbance .

Presentation Type: Poster
Session: P, Reproductive Processes
Location: Grand Ballroom - Exhibit Hall/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PRP012
Abstract ID:675
Candidate for Awards:Genetics Section Poster Award

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