I report on an ongoing project that intends to bring together the galaxy
content of observed and modeled galaxy clusters of the present-day universe.
The known nearby, massive galaxy clusters serve as our observational
reference. The model galaxies are provided by a recent semi-analytic model
that combines galaxy formation physics with simulated hierarchical structure
formation in a standard Lambda-CDM universe. We are particularly interested in
the question whether the properties of the observed large and diverse dwarf
galaxy population are reproduced in the model, something that could hardly be
investigated with earlier models. Should the model fail to reproduce them,
would it mean that many dwarf galaxies are created by environmental mechanisms
not included in the model? Or would it merely indicate that the complex
physics of galaxy formation is not yet fully understood?