XVI International Botanical Congess

Quaking aspen (Populus tremuloides) is subject to attack by a host of organisms. Striking intraspecific variation in resistance exists, and is related to secondary chemistry (phenolic glycosides and possibly condesed tannins). Foliar chemical composition is influenced by both environmental and genetic factors, and in turn influences bi- and tri-trophic interactions. Levels of the various secondary metabolites are differentially responsive to resource availability. Moreover, negative genetic correlations exist between growth and defense, and the strength of the correlation is resource-dependent. The remarkable evolutionary success of aspen is linked to genetic variation in commitment to growth and defense, modified by resource availability, resulting in a mosaic of chemical phenotypes in early successional habitats..