Population variation in Spartina anglica C. E. Hubbard

Publisher Website
Google Scholar
Abstract
Summary: The response of clonal replicates of nine populations of Spartina anglica C. E. Hubbard to environmental variation was examined in three pot environments, designed to test for differences between the populations in their response to environmental variation. ANOVA showed that the effect of environment was highly significant for all morphological and yield characters, and that the populations were also significantly different for several characters. For above and below ground vegetative biomass, there was a significant population x environment interaction, indicative of differences in plasticity between the populations. Linear regression of the population mean value in each environment on the mean value of all populations in each environment was performed for these two traits. This showed that the response to environmental change was not significantly due to a linear relationship in some populations, hence, the method could not be used to compare the response of each population. Nevertheless, norms of reaction plots for each population showed that the three populations collected from successionally mature sites showed less response to more favourable conditions. The three mature populations also had significantly lower tiller numbers per plant in all environments. These results substantiate previous results which suggest a decline in vigour and plasticity in successionally mature populations. Morphological characters, except third leaf width and culm diameter, all proved to be significantly correlated in pairwise comparisons. This is further evidence for the occurrence in S. anglica of ‘graceful’ and ‘stocky’ variants which contrast with the highly plastic ‘anglica’ growth form.