Document: MAR-3-46-9

Costs of plasticity in foraging characteristics of the clonal plant Ranunculus reptans.

VAN KLEUNEN, M.*, M.FISCHER and B.SCHMID

Universität Zürich, Zürich, Switzerland ¹

Abstract:
In clonal plants, evolution of plastic foraging by increased lengths of leaves and internodes under unfavourable conditions may be constrained by costs and limits of plasticity. We studied costs and limits of plasticity in foraging characteristics in 102 genotypes of the clonal herb Ranunculus reptans. We grew three replicates of each genotype with and three without competition by the naturally co-occuring grass Agrostis stolonifera. We used regression and correlation analyses to investigate potential costs of plasticity in leaf and internode length, developmental instability costs of these traits, and a developmental range limit of these traits. We used randomization procedures to control for spurious correlations between parameters calculated from the same data. Under competition the number of rosettes, of rooted rosettes, and of flowers was 58, 40, and 61 percent lower, respectively, than in the absence of competition. Under competition lengths of leaves and internodes were 14 and 6 percent smaller, respectively, than in the absence of competition. We detected significant costs of plasticity in internode length in the presence of competition when fitness was measured in terms of the number of rosettes and the number of flowers (selection gradients against plasticity were 0.250 and 0.214, respectively). Within-environment variance in both foraging traits was not negatively correlated with the corresponding plasticity, which indicates that there were no developmental instability costs. More plastic genotypes did not have less extreme trait values than less plastic genotypes for both foraging traits, which indicates that there was no developmental range limit. We conclude that in R. reptans costs of plasticity more strongly constrain evolution of foraging in the horizontal plane (i.e. internode length) than in the vertical plane (i.e. leaf length).

Keywords: clonal growth, costs of plasticity, developmental stability, foraging, genetic variation

This abstract is being presented at: 3:30 PM in session:
Oral Session #63: Evolutionary Ecology.