Plant ontogeny and the tradeoff between resistance and tolerance to herbivory in Arabidopsis
Plant defense against herbivory includes traits that decrease herbivore attack (resistance) and those that reduce the negative effect of damage (tolerance). Because of their cost and putative redundant function a trade-off between allocation to resistance and tolerance has been predicted. Since resource allocation patterns change through development, defense levels should change with ontogeny, but it is difficult to predict whether resistance and tolerance should co-vary negatively or not throughout ontogeny. Using 13 accessions of Arabidopsis thaliana from different parts of the world, we measured resistance and tolerance to a generalist herbivore at three ontogenetic stages.
Both resistance and tolerance increased throughout development. However, at each ontogenetic stage we found evidence of a trade-off between resistance and tolerance. Despite these general patterns, plants from certain accessions can allocate to both resistance and tolerance. No fitness cost of tolerance was detected. Had we measured plants at a mixture of ontogenetic stages, we would have not detected any trade-off between resistance and tolerance. Our study shows how ontogenetic changes in allocation to defense may influence our ability to detect a trade-off between resistance and tolerance.