Theoretical evolution of ³He and carbon isotopic ratio at the stellar surface as a function of surface gravity for stellar models of: left panels various masses (1.0; 1.2; 1.5; 1.8; 3.0 M_⊙ represented by a black, red, blue, green and orange solid line, respectively) at Z = 0.04; right panels various metallicities ([Fe/H] = 0.5; 0; −0.23; −0.54; −2.14 represented by a black, red, blue, green and orange solid line, respectively) at M = 1.2 M_⊙. These models include the effects of thermohaline instability (bottom panels) and following standard evolution (top panels). These tracks are shown from the main sequence up to the early-AGB.