Facing change: forms and foundations of contemporary adaptation to biotic invasions.

Ongoing adaptation in native populations to anthropogenic change both facilitates and challenges ecologically appropriate and sustainable management. Human disturbance promotes adaptive responses at the genomic, individual and population levels. Traits vary widely in whether adaptation occurs through plasticity or evolution, and these modes interact within and among traits. For example, plasticity in one trait may be adaptive because it permits homeostasis and lessens the intensity of selection in another. Both opportunity and catastrophe generate adaptive responses. Recently evolved adaptations characterize the responses of many native species to biotic invasions. Several well-known examples involve native phytophagous insects colonizing introduced plants. For example, our studies of North American and Australian soapberry bugs on nonindigenous plants demonstrate both diversifying and homogenizing contemporary evolution. Modes of adaptation differ among traits and populations and as a function of the host on which they develop. The genetic architecture of the evolving adaptations involves a substantial degree of nonadditive genetic variation. One important consequence of contemporary adaptation may be an enhanced capacity of native communities to provide adaptive biological control of invasive species. Conservation scientists may manipulate adaptation to achieve conservation goals, but must also decide how deeply they wish to attempt to control the phenotypes and genotypes of other species.