  We use the one-loop Chiral Perturbation
  Theory pion-pion scattering amplitude and dispersion theory in the form of
the inverse amplitude method, to study the quark mass dependence of the two
lightest resonances of the strong interactions, the f_0(600) (sigma) and the
rho-meson. As main results we find that the rho-pion-pion coupling constant is
almost quark mass independent and that the rho mass shows a smooth quark mass
dependence while that of the sigma shows a strong non-analyticity. These
findings are important for studies of the meson spectrum on the lattice.
