Plasticity's role in adaptive evolution depends on environmental change components.

To forecast extinction risks of natural populations under climate change and direct human impacts, an integrative understanding of both phenotypic plasticity and adaptive evolution is essential. To date, the evidence for whether, when, and how much plasticity facilitates adaptive responses in changing environments is contradictory. We argue that explicitly considering three key environmental change components – rate of change, variance, and temporal autocorrelation – affords a unifying framework of the impact of plasticity on adaptive evolution. These environmental components each distinctively effect evolutionary and ecological processes underpinning population viability. Using this framework, we develop expectations regarding the interplay between plasticity and adaptive evolution in natural populations. This framework has the potential to improve predictions of population viability in a changing world. Global biodiversity is jeopardised by unprecedented environmental change, the hallmark of the Anthropocene. To estimate the extinction risks of species, understanding how individuals and populations respond to changing environments is crucial. Adaptive evolution and phenotypic plasticity are two key mechanisms by which natural populations avoid extinction in the face of environmental change. However, the relative roles and interplay between the two are still unresolved. Whether plasticity hinders (H1) or facilitates (H2) adaptive evolution has been ardently researched, but without cross-study standardization of how changing environments impact whether (H1) or (H2) is more likely over time. We propose an integrative framework based on how key environmental components influence the 'building blocks' of ecoevolutionary responses to examine when plasticity aids or hinders adaptive evolution. We synthesise key microevolutionary and ecological processes regarding how natural populations respond to environmental change. Studies may benefit from this framework to deepen our understanding of how plasticity influences adaptive evolution by reframing H1 and H2 in the context of environmental change, and will thus increase our ability to forecast extinction risks in the Anthropocene. [ABSTRACT FROM AUTHOR]