Precipitation predictability drives evolution of drought strategies in the common poppy, Papaver rhoeas

Abstract

Abstract Current climate change leads to an increase in the frequency and intensity of droughts and to a decreased precipitation predictability. The few studies investigating plant evolutionary responses to contrasting predictability regimes showed that intrinsic precipitation predictability shapes plant phenotypic variation, drives evolution of phenotypic plasticity and can vary in strength and direction of selection. This suggests that the selection pressure induced by decreased precipitation predictability may lead to plants coping better with severe drought events. To investigate whether past precipitation predictability influences plant responses to different drought conditions, we performed a common‐garden experiment applying control, short‐term and long‐term drought treatments on seedlings of Papaver rhoeas (Papaveraceae) whose progenitors experienced less versus more precipitation predictability treatments for three consecutive generations. In addition, to assess whether competition modulates plant responses, half of the plants were grown together with the widespread herbaceous plant Galium album (Rubiaceae). In the presence of long drought episodes, plants whose progenitors experienced less predictable precipitation survived longer than those whose progenitors experienced more predictable precipitation. Furthermore, plants whose progenitors experienced less predictable precipitation had lower biomass, which is likely to reduce water loss via transpiration, and, across all drought treatments, they showed lower root investment. However, no trait differences were detected under competition, indicating that interspecific competition may limit the expression of evolutionary responses to changes induced by precipitation predictability. Altogether our results indicate that lower precipitation predictability mainly promotes the evolution of drought‐escape and drought‐avoidance strategies. Overall, our experiment highlights that precipitation predictability is an important evolutionary driver of plant functional responses, potentially shifting evolutionary trajectories of plants under increasing intensity of drought events. Read the free Plain Language Summary for this article on the Journal blog.