  Recent results on the detection of substructure in dwarf spheroidal galaxies
are discussed. In most cases they show that, when a galaxy experiences multiple
SF episodes, the intermediate age population is more centrally concentrated
than the old population, and that the recent SF is even more concentrated
towards the central regions. Moreover, it appears that the spatial distribution
of stars becomes more and more irregular as younger and younger subpopulations
are considered. We illustrate how wide-area observations, allowing a
substantial coverage of dwarf spheroidals (in particular the satellites of the
Milky Way), has provided evidence for cosmologically old populations in every
dSph galaxy. All these results are placed in the broader scenario of population
gradients in nearby dwarf galaxies of different morphological types.
