Genetic adaptation rates differ by trait and plant type --a comprehensive meta-analysis

Summary Plants can respond to changing climatic conditions through genetic adaptation of their functional traits. Despite the relevance of adaptation to climate change, much remains unknown about plant genetic adaptation rates, including whether these rates differ among plant characteristics and trait types. We performed a meta-analysis to investigate patterns of genetic adaptation rates and assess how these rates differ among plant species groups, growth forms and trait types, using a newly compiled database from 74 studies, comprising 35 functional traits across 72 angiosperm species. This database specifically focuses on genetic adaptation of plant functional traits, as separating from phenotypic plasticity. Both annual and generational adaptation rates of plant traits decrease non-linearly with increasing elapsed time since divergence. Plants adapt fastest when first introduced to a changing environment, but these rates go slow subsequently. Overall, shrubs have higher adaptation rates than trees, which confers shrubs an adaptive advantage over trees. Different adaptation rates among growth forms, life histories and trait types suggest an important additional mechanism through which climate change may affect community composition. Our study has important implications regarding plant adaptation to new environments and will improve the prediction of vegetation responses and ecosystem functioning upon climate change.