Dwarf galaxies, being the most numerous and fragile galaxy population, provide unique clues on both the formation of baryonic systems and the role played by the environment in galaxy evolution. In this short talk, I will present the main observational properties of the dwarf galaxy population in a sample of 88 nearby (z < 0.1) galaxy clusters drawn from the SDSS-DR4. By comparing the different properties (spatial and velocity distribution, colour, etc.) of red and blue dwarfs we attempt to constrain the scenarios for the evolution of galaxies in high-density environments.