Recent Topics Posters
Brzyski, Jessica , Culley, Theresa M. .
Is the Clonal Rare Spiraea virginiana Capable of Sexual Reproduction?
In plants, clonality and sexual reproduction often occur concurrently to provide reproductive assurance, which is especially important when barriers to gene flow exist. In addition, clonality and self-incompatibility tend to evolve together, possibly to prevent self-fertilization, which can lead to inbreeding depression. An ideal species for studying these issues is the rare shrub Spiraea virginiana. This species, occurring in streamside habitats, favors clonal reproduction through rhizomes, which can break off, wash downstream and colonize additional stream sites. Contrary to theory, it is thought that sexual reproduction is non-existent in S. virginiana, and that each population potentially represents a single genotype. If so, individuals of a population will be genetically identical, thus severely limiting their ability to adapt to a changing environment. This perceived lack of sexual reproduction of S. virginiana could be a potentially important biological limitation. To determine if sexual reproduction occurs in this species, we conducted a series of preliminary studies to characterize pollen viability, germination of field-collected seed, and seed production following hand-pollinations in the field. Pollen viability was tested by removing pollen from five flowers of each of nine clones, treating the pollen with Alexander’s stain, and counting viable and inviable pollen grains under a microscope. Two hundred pollen grains from each flower were examined under a microscope. Pollen viability was quite high, with over 90% viability for each clone. Although mature seeds are not commonly encountered in the field, they were obtained in 2007 and successfully germinated in a controlled greenhouse setting. Finally, hand pollinations were conducted in the field during June of this year using multiple pollen sources. Although still ongoing, results from this field experiment will determine if S. virginiana is capable of producing fruit through outcross pollen, therefore allowing us to conclude if the species is indeed capable of sexual reproduction.
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1 - University of Cincinnati, Department of Biological Sciences, 614 Rieveschl Hall, Cincinnati, OH, 45221, USA
2 - University of Cincinnati, Department of Biological Sciences, 614 Rieveschl Hall, Cincinnati, Ohio, 45221, USA
Presentation Type: Recent Topics Poster
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM