Climate change and its effects on body size and shape: the role of endocrine mechanisms.

In many organisms, rapidly changing environmental conditions are inducing dramatic shifts in diverse phenotypic traits with consequences for fitness and population viability. However, the mechanisms that underlie these responses remain poorly understood. Endocrine signalling systems often influence suites of traits and are sensitive to changes in environmental conditions; they are thus ideal candidates for uncovering both plastic and evolved consequences of climate change. Here, we use body size and shape, a set of integrated traits predicted to shift in response to rising temperatures with effects on fitness, and insulin-like growth factor-1 as a case study to explore these ideas. We review what is known about changes in body size and shape in response to rising temperatures and then illustrate why endocrine signalling systems are likely to be critical in mediating these effects. Lastly, we discuss research approaches that will advance understanding of the processes that underlie rapid responses to climate change and the role endocrine systems will have. Knowledge of the mechanisms involved in phenotypic responses to climate change will be essential for predicting both the ecological and the long-term evolutionary consequences of a warming climate. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'.