Meeting Abstract

52.5  Sunday, Jan. 5 11:15  Within-Fruit Seed Characteristics and Paternal Fitness of a Hybrid Plant and its Two Progenitor Lineages, Genus Raphanus HEREDIA , S. M.*; RIESEBERG, L. H. ; ELLSTRAND, N. C. ; University of British Columbia; University of British Columbia; University of California-Riverside sylviah@biodiversity.ubc.ca

The hybrid-derived California wild radish has outcompeted and replaced its two progenitor lineages in California. All three plants have pod-like fruits but in the hybrid, these are sired by multiple fathers in a non-random position. These unusual seed characteristics may be a key feature in explaining the competitive superiority of the hybrid. Here we address this hypothesis by directly comparing patterns of seed size, paternity, fitness, phenology and fruit structure from both progenitors and the hybrid. Our experiments revealed that the two progenitor lineages also have multiple paternity and that plant phenology patterns are influenced by maternity. However, only in the hybrid do fitness and fruit structure vary along the fruit consistently. These results indicate that multi-seeded Raphanus fruits provide an advantage of enclosing seeds with various genotypes maintaining high polymorphism. In the hybrid’s case the fruit provides additional protection to enhance fitness in stressful and competitive environments.