Circadian rhythms are highly conserved across the tree of life, with light serving as the primary cue for the circadian timer. Photoperiod variation follows a latitudinal gradient, reflecting fluctuations in seasonality that increases towards the poles. As photoperiod variability intensifies at higher latitudes, organisms must develop mechanisms to maintain circadian timing during prolonged periods of light or darkness. Consequently, latitudinal gradients in photic sensitivity occur, as populations in northern latitudes have physiologically adapted to significant seasonal variations in day length. However, the rise of urbanization has introduced artificial light on a global scale, creating new photoperiods for organisms to navigate. This artificial extension of the natural photoperiod is now interacting with evolutionarily established circadian rhythms. Because photic sensitivity follows a latitudinal gradient, this may also inform biogeographic patterns of vulnerability to light pollution. We introduce the term "circadian histories" to describe an organism's evolutionary history of circadian entrainment, which may influence its response to novel light pollution.

In ectothermic predator-prey relationships, the capacity for prey to successfully evade predation will depend upon physiological and behavioural responses that relate to both players’ thermal biology. On the Izu Islands of Japan, we investigated how a prey lizard species has responded physiologically and thermally to the presence of a snake predator over evolutionary time in addition to recent climatic warming. Foraging lizard body temperatures have increased by 1.0°C from 1981 to 2019 while lizard body temperatures were 3.4°C warmer on islands where the snake predator is present relative to snake-free islands. We also found that warmer prey body temperatures result in faster running speeds of the prey at temperatures suboptimal for the snake predator. The results show that lizard body temperatures have increased with warming but not to the same extent as that exerted by predation pressure. However, further warming could irrevocably alter this and other ectothermic predator-prey relationships.