PARENT SESSION
Contributed Oral Session 78: Evolutionary Ecology: Genetics
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 516 D, Level 5, Palais des congrès de Montréal
Scent emission and composition in Hesperis matronalis (Brassicaceae) varies with flower color, population of origin, and time of day.
Majetic, Cassie*,1, 2, Raguso, Robert3, Ashman, Tia-Lynn1, 1 University of Pittsburgh, Pittsburgh, PA2 Pymatuning Laboratory of Ecology, Linesville, PA3 University of South Carolina, Columbia, SC
ABSTRACT- Flower color and scent are well-known as potential targets of selection. Many studies suggest that a combination of visual and olfactory floral cues provide stimulus for pollinator and herbivore visitation. However, few studies have explored the relationship between color and scent, despite evidence for pleiotropic relationships between color and other chemical constituents in plants such as defensive compounds. Additionally, examining population-level or diurnal differences in scent among color morphs may provide greater insight into the variability of scent and thus potential impacts on visiting insect fauna. In this study, we determined the scent profiles of purple and white flower color morphs of Hesperis matronalis (Brassicaceae) using dynamic headspace extraction and GC-MS. PCA analysis allowed us to examine differences among color morphs from three populations (HS, RM, and RD) at two time periods (dawn and dusk) in terms of amount and composition of scent emitted for 33 volatile compounds. Color morphs did not differ in bulk emission, but color influenced scent composition, which varied among populations. Purple morphs have a greater proportion of aromatic compounds, while white morphs contain more terpenoids. Significant diurnal differences exist for all aspects of scent: plants at dusk emit more scent with a greater proportion of aromatics; plants at dawn emit a lesser amount dominated by terpenoids. Population of origin significantly affected all aspects of scent. Our data suggests that color morphs have specific volatile signatures, but a spatial and diurnal variation in emission and composition can temper this difference. Variable associations between visual and olfactory cues may have considerable impacts on pollinators and herbivores that use both scent and color as behavioral stimuli. Thus, evolution of scent and color driven by insect selective agents may vary in space and time.
Key words: floral scent, flower color polymorphism, Hesperis matronalis