Climate variability and the paradox of plasticity

Adaptive phenotypic plasticity, the ability of organisms to adjust their physiological responses to varying environmental conditions, is expected to evolve when conditions change predictably over time. This concept has led to the Climate Variability Plasticity Hypothesis (CVHP), which predicts that ectotherms in environments with low temperature seasonality, like the tropics, should develop lower thermal plasticity compared to those from more seasonal environments.

However, empirical evidence supporting the CVHP is scarce, prompting researchers to explore alternative factors that could influence the evolution of thermal plasticity. In a new study, scientists utilized numerical models to investigate how the evolution of constitutive thermal tolerance breadth impacts the benefits of thermal plasticity. Their findings suggest that tolerance breadth interacts with both within- and between-season temperature variation in ways that may challenge the predictions of the CVHP.

Interestingly, their models indicate that organisms from less seasonal environments might actually benefit more from expressing thermal plasticity compared to those from more seasonal backgrounds. This revelation implies that a more comprehensive understanding of the relationship between thermophysiology and environmental temperature is necessary to explain the evolution of thermal plasticity across various climatic gradients.