Sex-dependent evolution of life-history traits following adaptation to climate warming

1. Thermodynamic processes increase metabolic rate and decrease longevity at high temperatures in ectotherms. However, how sustained long-term increase in temperature affects the evolution of longevity is poorly understood. 2. Stress theory of ageing predicts that increased longevity is positively genetically correlated with resistance to different types of environmental stressors implying that evolutionary trajectories of ageing may be mediated by correlative selection for robust phenotypes under thermal stress. 3. Here, we test this hypothesis by using replicate populations of the seed beetle Callosobruchus maculatus, evolving under two thermal environments: ancestral 30 degrees C and incremental increase towards novel 36 degrees C. 4. Beetles evolving under climate warming became larger, more fecund and lived longer than the beetles evolving under 30 degrees C across both environments. However, the increase in longevity was partly due to parental effects because after two generations of acclimatization it persisted only in males. 5. Our results support the hypothesis that evolution of stress resistance confers increased longevity through positive pleiotropy but demonstrate that such effects can be sex specific. These findings suggest that sex differences can evolve as correlated responses to selection under environmental change.