Norms of Reaction of Seed Traits to Maternal Environments in Plantago lanceolata

Abstract

Environmental maternal effects can have important ecological and evolutionary consequences, yet little is known about genetic variation in the plastic response of offspring phenotype to maternal environment in natural plant populations. We therefore performed two experiments to investigate norms of reaction of seed weight, germination fraction, and germination rate to maternal environment in the common weed Plantago lanceolata. In the first experiment, seven wild-collected maternal genotypes from two sites, a mowed lawn and an abandoned hayfield, were clonally replicated and planted in randomized blocks in a reciprocal transplant design in the two natural source populations. In the second experiment, eight maternal genotypes from the same two populations were clonally replicated over four greenhouse environments in a factorial combination of two light and two fertilizer levels. Both experiments revealed a significant impact of parental environment on offspring traits. There were also significant differences among maternal genotypes within and across maternal environments, which suggests that natural selection can discriminate at this level. In addition, for certain traits, norms of reaction differed among maternal genotypes, which suggests that the plastic response of these traits to maternal environment can evolve. Moreover, in the greenhouse experiment the expression of maternal genotype and environmental effects on germination depended on the offspring's light environment, which suggests that the potential for natural selection to discriminate among maternal genotypes may differ among progeny environments.