Browsing by Author "Liu, Yan"

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    Genetics and evolution of ultraviolet reflectance in flowers
    (2018-01-25) Liu, Yan; Vamosi, Jana; Samuel, Marcus; Ro, Dae-Kyun; Melin, Amanda; Caruso, Christina
    Many flowers have ultraviolet (UV) reflectance patterns, which are invisible to humans but visible to pollinators, such as bumblebees and hummingbirds. In bees and hummingbirds, photoreceptors are sensitive to UV wavelengths, and it is therefore necessary to incorporate this variable to model pollinators’ perception and assess floral UV evolution. In this thesis, I explore micro- and macroevolutionary patterns in floral UV patterns, specifically concentrating on the effect of this phenotype on pollinators. I first explore the ways in which UV patterns can be measured and characterized, as well as explore the underlying basis of UV patterning in flowers. By gathering UV reflectance data (between 300 to 400nm) on 150 species, I found evidence that the phylogenetic distribution of UV trait disparity is consistent with a stabilizing selection model of evolution, but the magnitude of stabilizing selection varies with geography and pollinator syndrome. Mimulus species have become key model species for investigating the genetics of floral adaptations, in part because it is tremendous diversity in floral phenotypes. I firstly estimate genetic diversity in six populations in Alberta and British Columbia. Historical contingency (via geographic and bioclimatic events) provides the evidence of restricted gene flow. Variance in phenotypes depends not only on allelic interactions but also on environmental factors. Variation and heritability of the floral UV reflectance are further explored with experimental interspecific crosses between Mimulus guttatus and Mimulus luteus. By recoding 12 floral traits throughout the parental to F4 generations, I find that phenotypic covariance is strongest between UV reflectance and other floral traits, lending evidence to the idea that UV reflectance in flowers evolves along with other floral traits as a response to selection from pollinators. My research has implications for forecasting plant adaptation through hybridization and polyploidization, which may occur in concert with the evolution of plant-pollinator relationships.