Phenotypic plasticity and contrasting habitat colonization in Festuca pallescens

Abstract

Eight populations of Festuca pallescens (Poaceae) from southern Patagonia (Argentina) were chosen to test whether their morphology and anatomy were associated with climatic and edaphic characteristics of their habitats and to discriminate genetic and plastic components of the variation. Fourteen environmental variables were measured to characterize eight localities. Cluster analysis classified them into four habitats. Principal components analysis based on 22 morphological and anatomical characters of five individuals from each population was performed. This ordination grouped them by habitat. Small plants with a low number of spikelets were found in the xeric habitat, whereas plants of the saline habitat showed a significantly higher number of spikelets. Large plants were characteristic of the humid habitats, but at higher elevations of foothill humid valleys the plants produced few spikelets per panicle with larger lemmas and heavier propagules than those in the coastal humid plains. A larger sample of 10 populations drawn from across the distribution of F. pallescens showed that seed collected at high altitudes were significantly heavier then those collected near sea level. The same characters were measured again 1 year after transplanting to uniform conditions. Significant differences between habitats disappeared. These data showed that phenotypic plasticity allows for diverse habitat colonization of this widespread species. Key words: Gramineae, phenotypical plasticity, seed weight, principal components analysis, ecotypes.