Summary: EVOLUTIONARY ECOLOGY OF PLANT DEFENCES
Current trends in the evolutionary ecology of plant
Anurag A. Agrawal*
Department of Ecology and Evolutionary Biology and Department of Entomology, Cornell University, Ithaca, New York
1. In this essay I summarize current trends in the evolutionary ecology of plant defence, while
advocating for approaches that integrate community ecology with specific tests of classic evolu-
tionary hypotheses. Several conclusions emerge.
2. The microevolution of defence is perhaps best studied by reciprocal transplant experiments of
differentiated plant populations while simultaneously manipulating the presence of the herbi-
vore(s) hypothesized to be the agent(s) of natural selection.
3. Although there is continued interest in the costs of defence, I argue that some empirical
approaches to estimating costs (e.g. genetic engineering) may provide limited insight into evolu-
4. Essentially all plants employ several different lines of defence against herbivory. It is thus time
to abandon searching for single silver bullet traits and the simple trade-off model (where traits
are arbitrarily expected to negatively covary across genotypes or species). We still know very lit-
tle about which trait combinations are most effective and have repeatedly evolved together.