The role of maternal environment and dispersal ability in plants' transgenerational plasticity

Transgenerational effects enable the transmission of environmental cues from parents to offspring. Adaptive maternal effects are expected to evolve if the maternal (or parental) environment contains information about the environment experienced by offspring. This correlation between maternal and offspring environments should be strongest in plant species with reduced dispersal ability. However, studies relating dispersal ability to the strength of maternal effects are rare. This study aimed to explore whether and how the dispersal distance of species and individuals affects offspring plant performance. Using seven common European plant species, we conducted a multi-year common garden experiment exposing maternal plants to three different water conditions (mesic, drought and waterlogging). At the end of the season in the first year, seed heads were collected from the lower and upper parts of each mother plant and used for dispersal distance calculation. Offspring coming from the maternal lower and upper parts were exposed to the same water treatments as mothers. Contrasting our hypothesis, we found that maternal water experience and species' dispersal abilities did not influence offspring performance (plant aboveground, belowground, reproductive and dead biomass). We did not detect maternal effects, meaning that offspring plants with the same water conditions as their mothers had the same fitness as offspring with different water conditions. However, opposite to our expectations, the longer dispersal distance of individual seeds ensured a stronger maternal effect when exposed to the same water stress as their mothers. Consequently, a stressful environment would select for long-distance dispersal.