A resurrection experiment reveals the evolution of jack-and-master plasticity in a Mediterranean shrub

Abstract

In situ adaptive responses to climate change may involve evolution of both trait means and trait plasticity, yet empirical evidence linking rapid evolution with fitness consequences remains scarce. We used a resurrection experiment to test whether contemporary evolution has occurred in the Mediterranean gypsophile shrub Lepidium subulatum. We compared ancestral (1964) and descendant (2018) generations from the same population in a common garden implementing contrasting watering treatments, after controlling for seed storage effects and corroborating similar levels of neutral genetic variation between generations. Plants exhibited adaptive plasticity to drought in several leaf traits, resulting in a mixed resource-use strategy combining acquisitive (higher SLA) and conservative responses to drought (lower LA, higher LDMC). Evolutionary changes in trait means across generations mirrored the direction of plastic responses, supporting their adaptive value under increasing aridity. Plasticity patterns also evolved, with descendant genotypes expressing more acquisitive phenotypes under benign conditions but more conservative phenotypes under drought. These coordinated evolutionary changes were accompanied by increased opportunism: descendants showed greater reproductive output under well-watered conditions while maintaining comparable fitness under drought. Together, our results demonstrate rapid evolution of both trait means and their plasticity, leading to a jack-and-master fitness strategy. This study provides direct evidence that specialized Mediterranean plant populations can rapidly evolve in response to ongoing climate change.