No trade-off between trichome production and tolerance to leaf and inflorescence damage in a natural population of Arabidopsis lyrata

Early models of plant defense conceived resistance and tolerance to herbivore damage as mutually exclusive strategies. Support for this idea has been equivocal and studies on these two strategies are still needed to understand the evolution of defenses in natural populations. In Arabidopsis lyrata, the production of trichomes, a documented resistance trait, has been associated with a fitness cost in the absence of herbivores. We examined whether trichome production is also associated with reduced tolerance to simulated herbivore damage. We conducted a field experiment in a natural Swedish population of A. lyrata where we inflicted leaf (0 vs. 50% of the area of each leaf removed) and inflorescence damage (0 vs. 50% of inflorescences removed) to trichome-producing and glabrous plants in a factorial design. We examined the response (survival, growth and reproduction) of the plants to the imposed damage over 2 years. Trichome-producing plants were not less tolerant than glabrous plants to simulated herbivore damage (no significant morph x leaf damage or morph x inflorescence damage interactions). Inflorescence and leaf damage had independent negative effects on the performance of damaged plants. Leaf damage reduced rosette size the year of damage, but effects on reproductive output in the year of damage, and on survival and reproductive performance the following year were weak and not statistically significant. Inflorescence damage significantly reduced the number of flowers, fruits and seeds the year of damage, but not in the following year. Irrespective of morph, the study population was more tolerant to leaf than to inflorescence damage. The results indicated no trade-off between trichome production and tolerance, suggesting that these two defense mechanisms have the potential to evolve independently in this A. lyrata population.