GLOBAL CLIMATE-CHANGE AND PHENOTYPIC VARIATION AMONG RED DEER COHORTS

The variability of two fitness-related phenotypic traits (body weight and a mandibular skeletal ratio) was analysed among cohorts and age-cl asses of red deer in Norway Phenotypic variation among cohorts was pro nounced for calves, yearlings and reproductively mature adults. Fluctu ations in cohort-specific mean body weights and skeletal ratios of adu lts correlated with global climatic variation in winter conditions inf luenced by the North Atlantic Oscillation while cohorts were in utero. Red deer born following warm winters were smaller than those born aft er cold winters, and this inter-cohort variability persisted into adul thood. Phenotypic variation among cohorts of red deer influenced by cl imate change may pose consequences for fitness of cohorts since body s ize and condition contribute to reproductive success and survival in m ale and female red deer. In particular, the recent trend of increasing ly warm winters in northern Europe and Scandinavia may lead to reduced body size and fecundity of red deer, and perhaps other ungulates, in those areas.