Observed number of the RRLS in dSph satellites of the MW (circles) and M31 (triangles). A least-squares fit to the data is represented by a straight line. Note that greater than 1000 RRLS are expected in the CMa dSph galaxy if it has M _V ~ −14 (Martin et al. 2004a; Bellazzini et al. 2004; Martínez-Delgado et al. 2005) and follows the trend in this diagram. The position of Leo I, the MW dSph galaxy with the lowest S _RR (see Section 4), is marked.