  The high end of the stellar mass function of galaxies is observed to have
little evolution since z~1. This represents a stringent constraint for
merger--based models, aimed at explaining the evolution of the most massive
galaxies in the concordance LambdaCDM cosmology. In this Letter we show that it
is possible to remove the tension between the above observations and model
predictions by allowing a fraction of stars to be scattered to the Diffuse
Stellar Component (DSC) of galaxy clusters at each galaxy merger, as recently
suggested by the analysis of N-body hydrodynamical simulations. To this
purpose, we use the MORGANA model of galaxy formation in a minimal version, in
which gas cooling and star formation are switched off after z=1. In this way,
any predicted evolution of the galaxy stellar mass function is purely driven by
mergers. We show that, even in this extreme case, the predicted degree of
evolution of the high end of the stellar mass function is larger than that
suggested by data. Assuming instead that a significant fraction, ~30 per cent,
of stars are scattered in the DSC at each merger event, leads to a significant
suppression of the predicted evolution, in better agreement with observational
constraints, while providing a total amount of DSC in clusters which is
consistent with recent observational determinations.
