Zinc hyperaccumulation in Thlaspi caerulescens as a chemical defence against herbivory ABSTRACT Thlaspi caerulescens is one of several plant species known to accumulate heavy metals in excess of 2% of their above ground plant biomass. The reasons for hyperaccumulation are unknown, but several studies conclude that it may be a plant chemical defence. This has been of interest to biologists because these metals are usually toxic. The accumulation of these metals may serve as a model …showed first 75 words of 1010 total…

…showed last 75 words of 1010 total…defence mechanisms because of the increased fitness it allows for these plants. Herbivores were given a choice between accumulating and non-accumulating S. polygaloides, and the fitness of non-hyperaccumulating plants was 0.42 of that of the hyperaccumulators. Selective pressures could favor the evolution of these plants. All of these findings suggest that plants accumulating heavy metals may be utilizing an effective defence against herbivory and pathogens. They may also be good examples of the methods of coevolution.