Goodwillie, Carol , Ness, Jennifer M. .
Breeding systems and hybridization in Leptosiphon (Polemoniaceae).
Hybridization and breeding systems may interact in complex ways in plant species. Self-incompatibility is thought to be associated with greater selectivity in rejecting heterospecific pollen and therefore may limit hybridization. On the other hand, self-fertilization that occurs early in anthesis can also limit hybridization. Hybridization might influence mating system evolution either by introducing variation through introgression or by selecting for breeding system traits that reduce hybridization. Here we present a study of hybridization between Leptosiphon jepsonii, a primarily selfing species that contains variation in the timing of self-fertilization, and Leptosiphon androsaceus, its closest self-incompatible relative. At a site where the species co-occur in northern California, we detected a low frequency of hybrids using both AFLP marker and morphological data, which yielded remarkably congruent results. In greenhouse experiments, we are assessing the factors that contribute to reproductive isolation between the species, including pollen-pistil interactions and seed germination, viability and fertility of F1 hybrids. Preliminary data indicate that hybrids are viable but have high rates of male sterility. Pollen of L. androsaceus readily germinates and produces pollen tubes on stigmas of the selfing species, but in the reciprocal cross, most individuals of the self-incompatible species reject L. jepsonii pollen, suggesting that self-incompatibility limits the potential for hybridization. In an ongoing experiment with the selfing species, we are testing the hypothesis that the timing of self-fertilization affects the potential for hybridization and therefore might evolve to minimize the production of low fitness hybrids.
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1 - East Carolina University, Department of Biology, Howell Science Complex, Greenville, North Carolina, 27858-4353, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Wasatch A/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 4:15 PM