PARENT SESSION
Contributed Oral Session 132: Invasive Species: Management and Indicator Species
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 516 A, Level 5, Palais des congrès de Montréal
Solidago gigantea tolerance to herbivory: An evaluation of the EICA hypothesis.
Hull-Sanders, Helen*,1, Meyer, Gretchen1, 1 University of Wisconsin - Milwaukee, Saukville, WI, USA
ABSTRACT- Invasive, exotic plants cost millions of dollars in agricultural loss and damages annually and are believed to be second only to habitat loss in terms of their impact on native diversity. However, the mechanisms that allow plants to become invasive are still poorly understood. We tested the Evolution of Increased Competitive Ability (EICA) hypothesis that reasons if specialist herbivore pressure on exotic plants is reduced in the introduced range, then invasive plants should evolve to decrease their investment in defenses and therefore be less tolerant to herbivory. We evaluated tolerance to herbivory of both North American native and European invasive goldenrod, Solidago gigantea, plants using specialist chrysomelid beetles, Trirhabda virgata. Paired ramets of control and treatment plants were derived from 10 native and 20 invasive populations. Treatment plants were exposed to 10 − 14 feeding beetles for 3 wks. Damaged S. gigantea plants were found have an increased compensatory photosynthetic rate (PSR) (F1,303 = 125.24, P <0.001). Damaged native plant PSR was significantly higher than invasive plant PSR (F1,303 = 5.41, P = 0.02), suggesting that native plants were more tolerant after recent herbivore damage. However, at the end of the growing season invasive damaged and undamaged plants had a higher above ground biomass, contrary to EICA that predicts damaged invasive plants should be more susceptible to herbivores. European plants also allocated significantly more resources to asexual reproduction (F1,312 = 56.21, P < 0.001), but fewer resources to sexual reproduction than native plants (F1,313 = 5.30, P = 0.02).−
Key words: EICA, tolerance, herbivory, Solidago gigantea