RESUMO
Numerous studies of wild populations have shown that phenotypic traits can change adaptively on short timescales, but very few studies have considered coincident changes in major fitness components. We here examine adaptive changes in life-history traits and survival rates for wild guppies introduced into new environments. Female life-history traits in the derived (Damier River) populations diverged from the ancestral (Yarra River) population, as a result of adaptation to predation regime (high vs. low) and other aspects of the local river. Moreover, some components of the derived Damier populations, particularly juveniles, now show higher survival in the Damier than do contemporary representatives from the ancestral Yarra population. These results suggest that adaptive change can improve survival rates after fewer than 10 years (fewer than 30 guppy generations) in a new environment.