Understanding how species distributions will changes is one of the most prescient questions in biology, as scientists, conservationists and policy makers attempt to predict future patterns of biodiversity and the ecosystem services they provide. Investigations into how species physiologies are correlated with their environment, and the mechanisms underlying these correlations, are a crucial part of improving these predictions. The majority of recent shifts in species ranges have been correlated with increasing surface temperature, highlighting the key effect of temperature on ectotherms. However, multiple factors, such as ocean acidification and salinity, are likely to interact with changes in temperature, leading to shifts in the ecological balance.
Latitudinal gradients which incorporate a number of overlapping species ranges are “natural laboratories” for investigating the link between environmental variability and physiological flexibility. Recent advances in understanding the importance of aerobic capacity in setting temperature limits provide a framework for testing the physiological capacity of species that can be applied across these gradients. However, the importance of these mechanisms at different scales needs further investigation as we extrapolate from laboratory experiments to field scenarios. I use a combination of whole animal (e.g. behaviour and reproduction) and tissue biochemistry assays (e.g. metabolic pathways) to investigate the scale at which environmental variability best determines physiological flexibility.