Developmental plasticity and genotype-environment interactions influence valve morphology in the Cyclotella meneghiniana species complex (Bacillariophyceae)

Abstract

We investigated salinity-induced developmental plasticity and difference in the 'reaction norm' of clonal cultures (genotype-environment [G × E] interaction) of Cyclotella meneghiniana, isolated from different locations, and their F1 offspring. Genetic distances between strains and the phylogenetic position of each strain were investigated by partial 28S rDNA sequencing. In addition, we investigated morphological differences between cells obtained from different sites along a tidal river, from the lower reaches to the river mouth. In laboratory culture, all strains exhibited a greater number of central fultoportulae (CFP = central strutted processes) in saline medium (salinity, 17 psu) than in freshwater medium; the number of striae on the valve and the diameter of the central area increased in all but three strains. A significant G × E interaction was detected in the number of CFP, the number of striae, the diameter of the central area and the valve diameter. Pair-wise comparison showed significant G × E interactions for these traits among strain pairs. In the field-collected material, all parameters (CFP number, stria number, central area diameter and valve diameter) were greatest at the estuary mouth. © 2012 Copyright Taylor and Francis Group, LLC.