PHENOTYPIC PLASTICITY AND PLANT ADAPTATION

This paper focuses on phenotypic plasticity as a major mode of adaptat ion in plants. A methodological critique examines difficulties in stud ying plasticity, including the conceptually critical distinction betwe en functionally adaptive and inevitable aspects of response. It is arg ued that plasticity studies depend critically upon the genotypic sampl e, the choice of environmental factors and factor states, and the defi nition of phenotypic traits. Examples are drawn from recent studies sh owing adaptive response by genotypes to physical aspects of the enviro nment, as well as to biotic factors such as neighbour density and the presence of bacterial symbionts. Alterations of offspring traits by pa rental plants of Polygonum persicaria are discussed as a cross-generat ional aspect of plastic response to environment. Finally, individual p lasticity and local ecotypes are examined as alternative bases of spec ies ecological breadth, and methodological problems in distinguishing these alternatives are discussed.