A cross-seasonal perspective on local adaptation: metabolic plasticity mediates responses to winter in a thermal-generalist moth

The physiological and ecological impact of the thermal environment across life-stages can result in trade-offs that determine fitness and population dynamics. Understanding mechanisms and consequences of local adaptation for any organism that overwinters requires taking a cross-seasonal perspective. We used a trait-based approach to distinguish variation among ecotypes in ecological and physiological responses to overwintering conditions. We used fall webworms (Hyphantria cunea; Lepidoptera: Arctiidae) from Ottawa, Ontario and Columbus Ohio, representing the centre and periphery of the native range. We hypothesised that populations would be locally adapted to their overwintering environments, with fitness maximised under natal overwintering conditions. We predicted that this local adaptation would result from modulation of rates of energy use, growth and development. Each ecotype had higher overwinter survival in their natal compared to non-natal winter environment, and this was associa...