Conflicts in natural selection constrain adaptation to climate change inArabidopsis thaliana

Abstract

Adaptation to new environments can be impeded if beneficial phenotype combinations cannot coexist due to genetic constraints. To understand how such constraints may hinder plant adaptation to future climates, we compiled a comprehensive database of traits ofArabidopsis thalianaand estimated phenotypic natural selection in common gardens in its native distribution with rainfall limitation treatments. We found a natural selection conflict in drought environments as two drought-adaptive strategies, escape and avoidance, are mutually exclusive inA. thaliana. Traits underlying such strategies, such as flowering time, growth rate, and water use efficiency, are genetically correlated, and we identify novel loci involved in such correlation experiencing antagonistic natural selection. This empirical evidence shows that these adaptive strategies in natural populations are mutually exclusive due to strong genetic correlations amongst traits that limit the possible combinations of phenotypes. Given projections that future climates will become hotter and drier in many temperate regions, we expect an increasing conflict in natural selection among adaptive traits that could slow down or prevent adaptation. Our study underscores the importance of accounting for evolutionary genetic constraints when predicting how species may respond to a changing climate.