  When star clusters are formed at low star-formation rates (SFRs), their
stellar initial mass function (IMF) can hardly be filled continuously with
stars at each mass. This lack holds for massive stars and is observationally
verified by the correlation between star-cluster mass and its most massive
cluster star. Since galaxy evolution is strongly affected by massive stars,
numerical models should account for this lack. Because a filled IMF is mostly
applied even when only fractions of massive stars form, here we investigate by
3D chemo-dynamical simulations of isolated dwarf galaxies how deviations from a
standard IMF in star clusters affect the evolution. We compare two different
IMF recipes, a filled IMF with one truncated at a maximum mass at which a
single complete star forms. Attention is given to energetic and chemical
feedback by massive stars. Since their energy release is mass dependent but
steeper than the negative IMF slope, the energetic feedback retains a positive
mass dependence, so that a filled IMF regulates SF stronger than truncated
IMFs, though only stellar number fractions exist. The higher SFR of the
truncated IMF in the simulation leads to more supernovae II (SNeII), driving
galactic winds. Whether this results from the model-inherent larger SFR is
questioned and therefore analytically explored. This shows the expected result
for Lyman continuum, but that the total SNII energy release is equal for both
IMF modes, while the power is smaller for the truncated IMF. Reasonably, the
different IMFs leave fingerprints in abundance ratios of
massive-to-intermediate-mass star elements.
