Metal hyperaccumulation is a striking trait exhibited by many plant species, but the evolutionary ecology of metal hyperaccumulation is poorly understood. It has been widely hypothesized that metal hyperaccumulation evolved to protect plants from herbivory. However, there is currently little evidence that metal hyperaccumulation enhances the fitness of plants in the presence of herbivory. In this study, we conducted a multi-factor greenhouse experiment to examine the effects of two soil nickel concentrations (unamended (0 μg/g) and nickel amended (600 μg/g)), and three levels of artificial damage (0, 10 and 50%) on the growth of plants from two populations of Thlaspi montanum var. montanum. We observed a significant interaction between soil nickel and artificial damage. An a posteriori analysis of this interaction revealed that the presence of nickel significantly improved the ability of T. montanum to tolerate the negative effects of intense damage. Our results indicate that metal hyperaccumulation could benefit T. montanum by increasing its tolerance to damage. This study suggests that there is a potential for the evolution of metal hyperaccumulation in response to intense herbivory on T. montanum.
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Acknowledgements The authors thank Joshua Povich and Rebecca Welch for their help in the greenhouse. Comments and suggestions from members of the Simms lab at the University of California Berkeley and two anonymous reviewers greatly improved an earlier draft of this manuscript. The Department of Integrative Biology at the University of California Berkeley kindly provided us space in the growth chambers and in the greenhouse. This study was made possible through a Consejo Nacional de Ciencia y Tecnología
- Compensatory response
- Thlaspi montanum