Phenotypic plasticity and evolutionary demographic responses to climate change: taking theory out to the field

TLDR

Rapid climate change imposes strong selective pressures that alter growth, evolution, physiology, and development, and understanding population fates under global change requires analyzing the interplay of these processes—a long‑standing grey area in evolutionary biology. This review examines how phenotypic plasticity, genetic evolution, and demography interact in temporally or spatially changing environments, using tree drought responses and marine phytoplankton CO₂ rise as case studies to highlight neglected questions and challenges. The authors discuss limitations of current models and the difficulties of testing predictions in the wild, focusing on shifts in phenotypic selection, evolution of reaction‑norm variances, and transient dynamics, illustrated by the two landmark examples. The examples show that age‑specific plasticity and selection, as well as altered community interactions, must be further investigated to better understand evolutionary demographic responses to climate change in natural populations.

Abstract

Summary Rapid climate change both imposes strong selective pressures on natural populations – potentially reducing their growth rate and causing genetic evolution – and affects the physiology and development of individual organisms. Understanding and predicting the fates of populations under global change, including extinctions and geographical range shifts, requires analysing the interplay of these processes, which has long been a grey area in evolutionary biology. We review recent theory on the interaction of phenotypic plasticity, genetic evolution and demography in environments that change in time or space. We then discuss the main limitations of the models and the difficulties in testing theoretical predictions in the wild, notably regarding changes in phenotypic selection, the evolution of (co)variances of reaction norm parameters, and transient dynamics. We use two landmark examples of physiological responses to climate change –trees facing drier climate and extreme temperatures, and marine phytoplankton under rising CO 2 – to highlight relatively neglected questions and indicate the theoretical and empirical challenges that they raise. These examples illustrate notably that age‐specific patterns of plasticity and selection on the one hand, and changes in community interactions and functioning on the other hand, need to be further investigated theoretically and empirically for a better understanding of evolutionary demographic responses to climate change in the wild.