DISSERTATION RESEARCH: Hybridization, Polyploidy and Pollinator Behavior in Indian Paintbrush (Castilleja).

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The goal of this project is to understand how hybridization and polyploidy, in tandem, influence observed phenotypic patterns in natural populations, and how pollinator behavior, through selection, reinforces such patterns. This study examines 3 species of Indian Paintbrush that co-occur. In some locations, however, hybridization has obscured morphological distinctions between the species while in other locations species do not appear to hybridize and remain phenotypically distinct. We hypothesize that hybridization occurs in populations where the 3 co-occurring species have identical ploidy levels. In other plant systems, differences in ploidy levels between species can create barriers to reproduction. Plants from replicates of each type of population will be genotyped with AFLP markers and ploidy level will be determined by flow cytometry and chromosome counts. Pollination experiments in the field will determine whether pollinators, as agents of selection, help produce or reinforce observed patterns. Hybridization and polyploidy have been instrumental in the evolution of most plant lineages, yet how these processes and selection together influence landscape patterns of phenotypic variability has rarely been studied. By studying these two processes together, a greater understanding of their respective roles in the evolution of diverse plant lineages will be achieved.