Adaptive responses of plants to insect herbivores under climate change

Global climate change, including the rise of CO2 emissions and global warming, are predicted to alter the composition of communities through differential colonization abilities between sessile plants and their mobile insect herbivores along latitudinal and elevation gradients. In particular, under the scenario of increasing temperature, it is expected that insect abundance and diversity will increase at higher elevation and latitude. The outcome of novel interactions between previously non-overlapping plant and insect species will ultimately result from the ability of the plant to adjust its defence and tolerance strategy. However, plant responses to herbivory may also be directly impacted by the effect of CO2 and temperature on plant defensive hormonal pathways. Additionally, syndromes of plant defences and tolerance are driven by inherited functional traits, biotic and abiotic conditions and the geographical and historical contingencies affecting the community. Therefore, understanding evolutionary species responses to climate change and novel plant-herbivore interactions requires understanding of genetic variation, strength of phenotypic plasticity in response to herbivore attack and trait phylogenetic conservatism. We advocate the study along elevation gradients for predicting ecological and evolutionary outcomes of climate change on plant-herbivore interaction.