Two decades of resurrection studies: What have we learned about contemporary evolution of plant species?

PREMISE: Global climate change has altered the eco-evolutionary trajectories of plant species, leading to observed shifts in phenotypes, such as earlier flowering. However, disentangling the contributions of plasticity and adaptation to trait changes remains challenging. The resurrection approach is a powerful method to study genetic and plastic responses by contrasting ancestral and descendant lineages from the same populations under common conditions. METHODS: We compiled a database of resurrection studies to examine plant evolutionary responses to global change using a meta-analysis (46 studies) and quantitative and qualitative review (61 studies). Studies varied widely in the number of focal populations and intervening years separating generations, yet most involved annual plant species in North America and Europe. RESULTS: We found evidence for rapid, contemporary evolution in over half of the cases. Moreover, evolution was often adaptive. As hypothesized, annuals showed greater magnitudes of evolutionary change than perennials. Across studies, annual descendants evolved earlier phenology and more resource-acquisitive leaf traits relative to ancestors. Under drought stress, annual and perennial species both evolved earlier phenology. Furthermore, in response to drought, annuals evolved increased plasticity in phenological and physiological traits but reduced plasticity in leaf traits, whereas perennials showed no evidence for evolution in plasticity. CONCLUSIONS: Our study reveals that rapid evolution is common but not ubiquitous and highlights the key role of drought escape in plant responses to a warming world. Our review also suggests promising avenues for future resurrection research.