Ontogenetic phenotypic plasticity during the reproductive phase in Arabidopsis thaliana (Brassicaceae)

While phenotypic plasticity has been the focus of much research and debate in the recent ecological and evolutionary literature, the developmental nature of the phenomenon has been mostly overlooked. A developmental perspective must ultimately be an integral part of our understanding of how organisms cope with heterogeneous environments. In this paper I use the rapid cycling Arabidopsis thaliana to address the following questions concerning developmental plasticity. (1) Are there genetic and/or environmental differences in parameters describing ontogenetic trajectories? (2) Is ontogenetic variation produced by differences in genotypes and/or environments for two crucial traits of the reproductive phase of the life cycle, stem elongation and flower production? (3) Is there ontogenetic variability for the correlation between the two characters? I found genetic variation, plasticity, and variation for plasticity affecting at least some of the growth parameters, indicating potential for evolution via heterochronic shifts in ontogenetic trajectories. Within-population differences among families are determined before the onset of the reproductive phase, while among-population variation is the result of divergence during the reproductive phase of the ontogeny. Finally, the ontogenetic profiles of character correlations are very distinct between the ecologically meaningful categories of early- and late-flowering ''ecotypes'' in this species, and show susceptibility to environmental change.