Simon Morley: My research utilises latitudinal comparisons to understand the mechanisms that determine species physiological tolerance and plasticity. Latitudinal gradients which incorporate a number of overlapping species ranges are "natural laboratories" for investigating the link between environmental variability and physiological flexibility. 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. The importance of these mechanisms at different scales needs further investigation as we extrapolate from the findings of laboratory experiments to expectations of responses of natural populations. These findings are used to model the vulnerability of assemblages, species and populations to environmental variability and climate change, projecting future patterns of biodiversity.