Recent research suggests that intraspecific diversity plays important roles in ecosystem function, such as productivity and resilience to climate change. While many studies have shown a positive relationship between genotypic diversity within a single species and productivity, others have shown different direction and strengths in the diversity-productivity relationship depending on the measure and type of genetic diversity. Inherent in the implication of the importance of genotypic diversity on productivity is the idea that diversity at the genetic level translates into phenotypic trait diversity that allows the community to enhance overall productivity. Therefore a genotype’s propensity for phenotypic plasticity may be a key driver to increasing community productivity, particularly under varying environmental conditions. We manipulated genotype richness as well as genetic variation for phenotypic plasticity of Arabidopsis thaliana grown in combination under drought and non-drought conditions. Each genotype was grown alone and in combination with 6 individuals for each water treatment. Manipulated genotype richness was either 1, 3, or 6 genotypes. Manipulated plasticity was either high or low as determined by phenotypic change (fitness, aboveground biomass) of genotype grown alone under drought and non-drought conditions. Aboveground productivity for each community was measured.
Results/Conclusions
From this greenhouse experiment, we were able to determine 1) the relationship between genotype and phenotypic plasticity and 2) the relative importance of genotypic richness versus genetic variation for phenotypic plasticity under drought and non-drought conditions. We found certain genotypes to have higher phenotypic plasticity than others. In addition, we found a weak but significant relationship between genotype richness and overall fitness, but not productivity, for communities grown in drought and non-drought conditions. Diversity combinations composed of genotypes with higher propensity for phenotypic plasticity had greater overall fitness and productivity under both drought and non-drought conditions. Finally, diversity treatment combinations composed of genotypes with lower propensity for phenotypic plasticity exhibited little change, and lower overall fitness and productivity between drought and non-drought conditions. Together, these findings suggest that genotypic richness is only one facet of intraspecific variation that is important in the diversity-productivity relationship. Genetic propensity for plasticity can also drive diversity-productivity relationships under varying environmental conditions.