Abstract details

After a brief review of the observational evidences indicating how the populations of Be stars, red/blue supergiants, Wolf-Rayet stars, type Ibc and type II supernovae vary at different metallicities, we discuss the implications of these observed trends for our understanding of the massive star evolution. We shall show how the inclusion of the effects of rotation in stellar models improve significantly the correspondance between theory and observation. Consequences for the nucleosynthesis, the properties of the first stars and for the nature of the Gamma Ray Burst progenitors will be discussed.