  We analyse the dark, gas, and stellar mass assembly histories of low-mass
halos (Mvir ~ 10^10.3 - 10^12.3 M_sun) identified at redshift z = 0 in
cosmological numerical simulations. Our results indicate that for halos in a
given present-day mass bin, the gas-to-baryon fraction inside the virial radius
does not evolve significantly with time, ranging from ~0.8 for smaller halos to
~0.5 for the largest ones. Most of the baryons are located actually not in the
galaxies but in the intrahalo gas; for the more massive halos, the intrahalo
gas-to-galaxy mass ratio is approximately the same at all redshifts, z, but for
the least massive halos, it strongly increases with z. The intrahalo gas in the
former halos gets hotter with time, being dominant at z = 0, while in the
latter halos, it is mostly cold at all epochs. The multiphase ISM and thermal
feedback models in our simulations work in the direction of delaying the
stellar mass growth of low-mass galaxies.
