Mate Choice in Phlox Wildflowers

Abstract

Mate choice determines when, where, and how reproduction occurs. The summed effect of these decisions across generations drives evolutionary trajectories and patterns diversity across biological scales. Inspired by these far-reaching impacts, I focus on two primary arenas where plant mate choice decisions occur: 1) organismal interactions between plants and their pollinators and 2) cellular interactions between reproductive structures within the flower (pollen and pistil). In Chapter 1, I quantify the pollination environment in the Texas wildflower, Phlox drummondii, and identify high pollinator specialization towards a single butterfly species. Building on this empirical work in Chapter 2, I generate a novel theoretical framework for the role of pollinators as agents of dispersal. In Chapter 3, I test the hypothesis of increased self-fertilization in P. cuspidata as an adaptation to avoid costly hybridization with its related congener, P. drummondii. In Chapters 4 and 5, I use quantitative and functional genetics to investigate the genetic basis of the self-incompatibility mechanism active in P. drummondii. I map the genetic basis of intraspecific variation in the self-pollen rejection response and identify a novel gene causing self-pollen recognition in Phlox wildflowers. Taken together, my work integrates broad experimental approaches to explore how mate choice mechanisms function across biological scales.