Phenotypic and isozyme variation in Cystopteris fragilis (Pteridophyta) along an altitudinal gradient in Switzerland

Abstract

Plants of Cystopteris fragilis from 9 different populations along an altitudinal gradient and from two additional populations were investigated. In three populations at 1410 m, 1630 m and 1830 m a.s.l., respectively, climatic conditions were recorded. The phenology of the plants, the sizes and dimensions of leaves and fitness parameters such as leaves per plant and fertility were studied. Leaf sizes and leaf number per plant were negatively correlated with altitude. However, the duration of development from snow melt and onset of the leaves till ripening was similar at different altitudes. Additionally, isozyme investigations and chromosome counts of a set of randomly sampled plants were performed. The genetic differentiation between populations suggests a relatively low gene flow. A significant positive correlation between number of enzyme phenotypes and altitude was recorded. Two different cytotypes were distinguished, a hexaploid and a pentaploid one.