REACTION NORMS OF Arabidopsis. II. RESPONSE TO STRESS AND
UNORDERED ENVIRONMENTAL VARIATION
Massimo Pigliucci*, Carl D. Schlichting, Jeannette Whitton
Department of Ecology and Evolutionary Biology
University of Connecticut
Storrs
CT 06269
USA
* Author for correspondence. Current address: Ecology and
Evolutionary Biology, Box G-W, Brown University, Providence, RI
02912 (pigliucc@brownvm.brown.edu)
Functional Ecology, in press
Genetic variation, plasticity (i.e., the ability of a genotype to
produce different phenotypes in response to distinct
environments) and genotype x environment interaction have been
studied in four populations of Arabidopsis thaliana exposed to a
set of treatments including one "optimal" and three "stressful"
conditions. We found strong phenotypic plasticity for all nine
traits measured, highly significant genetic variation among
populations for all traits except for two of those directly
related to reproductive fitness, and genetic variation for the
plasticity of phenological, vegetative, early size, and one
fitness-related character. Flowering time and life span formed a
distinct covariance set clearly separating the populations into
late-, intermediate- and early-flowering (an ecologically
important aspect of A. thaliana phenology). Uni- and multivariate
analyses of variance revealed that more within-treatment
genetic variance for traits tended to be expressed under
"stressful" conditions than in the "optimal" treatment. However,
we suggest that the frequency of occurrence of the environments
might be more important than their "stressfulness" in determining
genetic and phenotypic changes. Comparison of the components of
phenotypic variance measured in a series of unordered treatments
with those components measured under several ordered treatments
(from a parallel study) revealed that the amount of genetic
variation for plasticity tends to be higher in the set of
unordered treatments.
Return to Contents Page: Weeds World Vol2(i)