Ecotypic differentiation within Festuca rubra L. occurring in a heterogeneous coastal environment

Abstract

In order to study the genetic differentiation between Festuca rubra L. individuals growing in a heterogeneous environment, indices of salt tolerance, mean relative growth rates and the numbers of tillers formed by plants grown in a Hoagland solution, were determined. It was found that plants from salt marsh sites have a high index of salt tolerance, a high mean relative growth rate and numerous tillers; plants from coastal sand dunes are less tolerant, grow slowly and form few tillers; plants from the inland polder sites are rather salt sensitive, fast growing and form a high number of tillers. The heritability of the mean relative growth rate and the tiller number appeared to differ from zero. Apparently, these characters have been under recent selection and thus give a picture of the adaptations of individual plants to the different environments encountered. An indication of gene flow has been found, although the effect of gene flow seems to be small in the face of the force of selection.

It was concluded that the distinction of three ecotypes within the species F. rubra is insufficient to describe the differentiation found. Considering the differences observed, it seems more reasonable to speak of ecotypic variation.

Nomenclature follows Heukels & van Ooststroom (1977).

The authors are indebted to Prof. Dr W. H. O. Ernst and Dr J. A. C. Verkleij for helpful suggestions during the investigations and for critically reading the manuscript, to Drs T. Dueck for correcting the English text and to Miss D. Hoonhout for typing the manuscript. The investigations were supported by the Foundation for Fundamental Biological Research (BION), which is subsidized by The Netherlands Organization for the Advancement of Pure Research (ZWO).