Mating system evolution
Organisms employ a remarkable variety of strategies to pass on genes from one generation to the next. In Angiosperm plants, individuals typically cross-fertilize (transfer gametes from one individual to another) or self-fertilize (fertilization occurs within a single flower) and some are capable of both. As part of my dissertation work, I studied the phenotypic and genetic changes that occur when plants that prefer to cross-fertilize (or outcross) are forced to self-fertilize (or self). Plant populations are increasingly under environmental stress due to climate change and this research helps predict their ability to adapt to pollinator loss. You can read more about this project in Bodbyl Roels & Kelly, 2011 (Bodbyl_Evolution_Mimulus.pdf)
Many plant species rely on pollinators for reproduction and have evolved complex attractive phenotypes, coevolving with pollinator sensory systems to enhance reproductive success. Coevolved phenotypic traits include floral architecture (shape/size), color, scent, and nectar/pollen rewards. Different pollinator groups appear to select for distinct suites of traits, which may converge in plants of dissimilar evolutionary origins, creating recognizable pollination syndromes. For instance, flowers pollinated by hummingbirds tend to be red and tubular in shape. I am interested in how specific pollinator preferences shape floral traits. To test pollinator preference, I create behavioral experiments where bumblebees can choose among various combinations of floral shapes and sizes.
Floral ultraviolet patterning
It’s easy to forget that not all creatures perceive the world in the same way that we do. Mimulus flowers appear to be a bright, sunny yellow, but there is more ‘color’ there than meets our eyes. Insects, birds, and bats can see in the near ultraviolet (UV) spectrum (200-400 nm), wavelengths that can not be detected by the human eye. Most flowers either fully reflect or absorb UV light, but at least 7% (including Mimulus guttatus) create contrasting patterns of UV reflectance and absorbance upon the floral surface (see the UV photos of two M. guttatus flower at right, in blue). These patterns are thought to have a variety of functions, from attracting pollinators to acting as sunscreen for the reproductive tissues. I’m investigating how much variation occurs in the UV patterns within and among species of Mimulus, and whether or not variation can be attributed to environmental factors such as pollinator guilds or elevational gradients. I also am interested in pinning down the chemical basis of the UV patterns and determining whether or not the compounds are co-opted from other important plant signaling functions (such as between roots and microbes in legumes) or have independently evolved.