  Our unified chemical and spectrophotometric evolution code allows to
simultaneously study the ISM abundances of a series of elements and the
spectral properties of the stellar population in our model galaxies. We use
stellar evolutionary tracks, yields, spectra, color and absorption index
calibrations for 5 different metallicities and account for the increase in
initial metallicity of successive generations of stars. For any kind of stellar
system, as described by its star formation history and IMF, we thus can
directly compare the time evolution of gaseous and stellar abundance ratios.
Spiral galaxy models that successfully reproduce spectral properties as well as
ISM abundances of nearby templates are combined with a cosmological model and
compared to damped Lyman $\alpha$ absorbers. For early type galaxies various
formation scenarii -- initial monolithic collapse, spiral-spiral merger,
hierarchical formation -- are tested with respect to their predicted spectral
energy distributions from UV to NIR and absorption indices and index ratios, as
e.g. [MgFe].
