Assessing the frequency of local adaptation and phenotypic plasticity in plants using a meta-analysis

Background/Question/Methods Plants are able to create and maintain successful phenotypes in different environments and under heterogeneous conditions. The phenotypic adjustment to environmental variation could be explained by the interaction between the environment and genotype (phenotypic plasticity) or as a consequence of differences in genotype (local adaptation). Although both strategies are reported in the literature, it is not clear which strategy is more common in plants. We conducted a meta-analysis using reciprocal transplant studies of plants. Our analysis included all traits reported in each study. We assessed uncertainty in our results by bootstrapping our data, and reduced bias due to correlation among traits by repeatedly selecting one trait per study in our study. In this way, local adaptation was defined as no differences within populations across environments. Plasticity was defined as phenotypic differences across environments, considering both adaptive (a similar expression as the optimal phenotype across the environment) and maladaptive plastic responses (a dissimilar expression from the optimal phenotype). Results/Conclusions

Our meta-analysis included 220 records from 37 studies where 52% of the records were for reproductive, 43% morphological and 5% physiological traits. Local adaptation was slightly more frequent than phenotypic plasticity in our analysis, with 56% of our records showing local adaptation. Of the remaining 44% with plastic responses, 69% were adaptive and 31% were maladaptive. Overall, 56% of our records were locally adaptive, 30% were adaptively plastic and 14% were maladaptively plastic. Our results suggest that local adaptation is a more common mechanism for effectively responding to environmental variation than is phenotypic plasticity. Our analysis indicates that most plants will not be able to adjust to climate change through plastic responses, but rather will need to shift their geographic range or adapt in a short time.