Predictable evolution of plant defense on uplift islands

Background/Question/Methods

When blank patches are uncovered to neighboring ecological communities they are often colonized by plants, herbivores, and carnivores in a highly predictable temporal order, which is the case in species-poor Bothnian land-uplift archipelagos. This implies that colonizing plants first will experience a time window of herbivore-free space, selecting for reduced resistance in favor of growth, followed by a time period of strong herbivory selecting for increased resistance at the expense of growth. To demonstrate this phenomenon I used an archipelago where young islands early become suitable for establishment of the perennial herb Meadowsweet, while selective leaf beetles cannot establish until the islands reach such a height (age) that the beetles are not washed away from their overwintering sites.
Results/Conclusions

I show that the mean phenotypic resistance against leaf beetles increases with island age, corresponding to the fitness reduction selectively imposed on susceptible host plants during historic herbivory. I further show that the raised resistance on old islands complicates the lives of the beetles which gradually become more prone to utilize a less suitable alternative host-plant species. These results demonstrate the possibility to study evolutionary interactions in rising archipelagos.