Effects of air pollution on biogenic volatiles and ecological interactions.

Chemical signals play important roles in ecological interactions but are vulnerable to perturbation by air pollution. In polluted air masses, signals may travel shorter distances before being destroyed by chemical reactions with pollutants, thus losing their specificity. To determine which scent-mediated interactions are likely to be affected, we review existing literature to build a picture of what chemicals are commonly found in such interactions and the spatial scales at which interactions occur. We find that pollination, attraction of natural enemies of plant pests, aggregation pheromones, and mate attraction are likely to be affected. We review the scant literature on this topic and extend the hypothesis to include heretofore unexplored interactions. New research should investigate whether air pollution deleteriously affects populations of organisms that rely on scent plumes. Additionally, we need to investigate whether or not breakdown products created by the reaction of signaling chemicals with pollutants can provide usable signals, and whether or not there has been adaptation on the part of scent emitters or receivers to use either breakdown products or more robust chemical signals. The proposed research will necessarily draw on tools from atmospheric science, evolutionary biology, and ecology in furthering our understanding of the ecological implications of how air pollution modifies the scentscape.