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Herbivory and Glucosinolates: Given the central role of spatial and temporal variation in theories of host-enemy coevolution, we established 14 long-term census populations across our study area. Naturally-occurring herbivore damage on individual plants has been censused during the growing season for the past five years. These results show ecologically and evolutionarily important levels of herbivory on Boechera, with extensive variation among sites and years. Boechera genotypes show heritable variation for insect resistance in lab and field experiments, and we are working to clone one of these resistance genes.
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| Arabidopsis and other Brassicaceae contain genetically polymorphic secondary compounds called glucosinolates. Generalist insects are sensitive toward glucosinolate-based plant defenses, whereas specialists can cope with these compounds, which often serve as oviposition cues and feeding stimulants. These contrasting biological effects of glucosinolates on different herbivores suggest ecological tradeoffs, resulting in balancing natural selection and elevated levels of nucleotide and amino acid polymorphism. Despite genetic and evolutionary evidence for non-neutral evolution of glucosinolate compounds, the ecological influences on glucosinolate polymorphisms remain unclear. For this reason, we are studying the effects of glucosinolates on herbivore resistance and fitness in undisturbed natural populations.
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