Upper panel: the dynamical (M/L)_dyn ratio (calculated assuming Newtonian dynamics to be valid in the weak-field limit) in dependence of the luminosity, L_V, for pressure-supported stellar systems following Dabringhausen et al. (2008). Note that here dE ( < 10¹⁰L_⊙) and E ( > 10¹⁰L_⊙) galaxies are both plotted with the same symbol. Lower panel: the Newtonian acceleration (Eq. (18)) of a star located at the effective radius within the host system in dependence of the host luminosity. The dashed line is a₀. Note that M/L_dyn is high in pressure-supported stellar systems only when a < a₀. In both panels: UCD  =  ultra compact dwarf galaxy. Comparing the upper and lower panels shows that evidence of DM (M/L_dyn > 10) appears only when a < a₀.