Garden, greenhouse, or climate chamber? Experimental conditions influence whether genetic differences are phenotypically expressed.

Common-environment experiments are important to study genetically based phenotypic variation within and among plant populations. Such experiments can be performed in an experimental garden, greenhouse, or climate chamber. However, phenotypic expression may be strongly affected by the environmental conditions and influenced by parental and storage effects. In particular, when the expression of genetically based phenotypic variation depends on the environment (G × E interaction), it can strongly influence conclusions. In this study, we assessed the effects of three different growth facilities - outdoor garden, greenhouse, and climate chamber - on phenotypic expression. We compared ancestral and descendant genotypes of the same population of Leontodon hispidus. We further evaluated differences in phenotypic expression between plants grown after one (F1) vs. two (F2) intermediate generations. As expected, we observed strong differences among plants growing in different environments (i.e., facilities). More importantly, we found that descendants had larger rosettes than ancestors only in the greenhouse and they flowered later than ancestors exclusively in the climate chamber, indicating G × E interactions. We did not find significant differences between different intermediate generations within the growth facilities. Overall, our study demonstrates that environmental variation among growth facilities can determine both the presence and magnitude of phenotypic differences. Consequently, differences observed in certain experimental settings may be overestimated compared with expression under natural conditions. Concluding, we recommend combining greenhouse and growth chamber resurrection experiments with field experiments to obtain a more comprehensive understanding of evolutionary changes.