The choice of genetic material for mechanistic studies of adaptation in forest trees.

There is considerable urgency to study the mechanisms by which forest trees track environmental change, given the prospect of possible rapid climatic changes. Environmental tracking is achieved through three basic processes: (1) expression of phenotypic plasticity at the level of the individual; and (2) evolutionary change and (3) migration, both expressed at the level of the population over generations. The current distribution and genetic architecture of a species reflect how these processes interacted in response to past climatic changes during and after the last glaciation. Part of that record is encoded in the DNA of the current generation of trees and, as a result of existing field tests, is accessible for study. These field tests include, in ascending order of genetic resolution, (1) provenance tests, (2) progeny tests, and (3) three-generation clonal tests; as well as (4) clone tests, with or without genetic structure. The suitability and limitations of these tests for mechanistic studies of environmental tracking are described, both as field installations and as sources of material for parallel in-depth studies. We conclude that they represent an important information resource, which deserves to be more effectively used by the scientific community.