  In this work, we study the Luminosity-Metallicity relation (LMR) and the
Stellar Mass -Metallicity relation (MMR) of galactic systems in a hierarhical
clustering scenario. We performed numerical hydrodynamical simulations with the
chemical GADGET-2 of Scannapieco et al.(2005) in a LCDM universe.
  We found that our simulated galactic systems reproduce the observed local LMR
and its evolution in zero point and slope. The simulated MMR is also in
agreement with recent observational results. From the analysis of the evolution
of the MMR, we found a characteristic mass at ~10^(10.2) M_sun / h which
separates two galactic populations with different astrophysical properties.
More massive systems tend to have their stars formed at z > 2 and show less
evolution than smaller systems. Hence, this characteristic mass is determined
by the formation of the structure in a hierarchical scenario. Our results also
suggest the need for important supernova feedback.
