PARENT SESSION
Oral Session # 49: Invasive Species IV: Grasslands; Wetlands.
Presiding: F Hughes
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 204.
Ecological and evolutionary responses of native species to novel community members: Direct and indirect effects of invasion.
Lau, Jennifer1, 1 UC Davis, Davis, CA
ABSTRACT- When a novel species enters a community, it can have both direct and indirect effects on native species within that community. For example, plant invaders can affect native plants both directly, via competition, or indirectly by altering the native species′ interactions with other organisms within the community. My work addresses the ecological and evolutionary consequences of the invasion of an exotic plant and its effects on a co-occurring native via competition and through the native plant′s interactions with its herbivores. The exotic plant Medicago polymorpha increases levels of herbivory on the native plant Lotus wrangelianus by increasing densities of legume-feeding herbivores. Phenotypic selection analysis revealed that Lotus individuals in the presence of Medicago experience more intense selection for resistance to weevil folivory than Lotus individuals in the absence of Medicago. Evolutionary responses to direct competition with the Medicago were also observed. The present study uses a two-by-two factorial design where both herbivore presence and Medicago presence are manipulated to determine the relative roles of indirect and direct effects of an invader on both the ecology and evolution of native L. wrangelianus.
Key words: evolution of plant defense, indirect effect, plant-herbivore interaction, invasive species