PARENT SESSION
Monday, August 7, 8:00-11:30 am
COS 7 - Evolutionary ecology I
L-14, Lobby Level, Cook Convention Center
Presiders: K Mercer
Variation in mating system and defensive traits in the Mimulus guttatus species complex.
Carr, David1, Eubanks, Micky2, Amsberry, Lindsay2, 1 University of Virginia, Boyce, VA2 Department of Entomology and Plant Pathology, Auburn, AL
ABSTRACT- The evolution of highly selfing mating-systems in the genus Mimulus is strongly associated with a decrease in corolla size, stigma-anther separation, and a decrease in development time. In a survey of 20 sites along a stratified transect in central California, we found that trichome density was positively correlated with flower size, stigma-anther separation and time to first flower. In previous work we demonstrated that the density of these glandular trichomes correlated negatively with spittlebug performance, and we interpret the covariance of trichome density and floral traits as evidence that selfing Mimulus taxa and populations invest less in defensive traits. Conversely, when 8 large-flowered M. guttatus populations were experimentally inbred, we found that trichome density increased significantly relative to outbred controls. The apparent heightened investment in defensive structures in these inbred plants is similar to many observations of environmentally stressed plants and is consistent with evidence from Hull-Sanders and Eubanks that suggests that inbreeding may act as an additional stress in plant-herbivore interactions. Taken together, our survey and experimental data suggest that the trajectory of trichome evolution in selfing populations of Mimulus runs counter to the effect of selfing on the trait itself.
Key words: mating-system evolution, herbivory, Mimulus