A central question in evolutionary physiology is how complex physiological adaptations evolve in response to natural selection operating on performance traits hypothetically associated with Darwinian fitness. We approached the problem using a unique experimental evolution model system: lines of a non-laboratory rodent, the bank vole, selected in three distinct directions: high exercise-induced aerobic metabolism (A), the ability to cope with a low-quality herbivorous diet (H), and intensity of predatory behaviour towards crickets (P). Four replicate lines are maintained in each of the selection directions and unselected control (C). The selection was effective and we observed several correlated responses to the selection in behavioral, morphological, physiological and life history traits. The selected lines provide a unique model to study genetic correlations between thephysiological and behavioural traits, as well as cellular, biochemical and molecular factors underlining changes of the traits observed at phenotypic organismal level.