e.g. dwarf irregular galaxies (dIrrs) with exceedingly strong star formation (SF), called starburst DGs (SBDGs), and also short but intense epochs of SF in the past, dwarf elliptical galaxies (dEs) with recent SF or central gas content, and last but not least, dwarf spheroidals (dSphs) at the faint end of dEs as satellite galaxies down to about -5$^m$. ”Normal” DGs have a brightness range between M$_V \ge -18^m$ to -10$^m$.

For this brightness reason, dSphs are only detectible within the Local Group by refined search algorithms from surveys as e.g. SDSS. Also in the Virgo Cluster an archival work of detailed dE properties is expensive in observing time. In their studies of Virgo cluster DGs already Sandage & Biggeli [@sb84] found that dEs dominate the cluster galaxy population by far, in contrast to their number fraction in the field where dIrrs are the most common DGs. This fact cannot be interpreted from the different local origins of DGs but because matter accumulates to clusters also dIrrs fall in from the cosmic web continuously whereby they have to change their morphology. Not only because of such morphological mutation but also due to the occurrence of enhanced SF in dIrrs, [@sb84] emphasized 