The irregular dwarf galaxy IC10 is located within the Local Group (LG) at a distance of 750 kpc, being the nearest starburst galaxy. Although several studies have revealed the existence of stellar populations with a broad range of ages, its star formation history (SFH) and age-metallicity (AM) relationship remain quite unknown.

In this talk I will discuss GMOS-Gemini spectroscopy of IC10, which includes 15 HII regions, 9 planetary nebulae (PNe) and 1 symbiotic star --so far the farthest known symbiotic binary. Our main goal is to reconstruct the SFH of IC10 and to constrain its AM relationship using young and intermediate-age stars. The direct availability of the electron temperature in our emission-line spectra allows an accurate determination of the IC10 metallicity map at two different epochs. We find an heterogeneous distribution of metals at both epochs, but similar average abundances for the two analyzed populations. The derived AM relationship shows a little global enrichment, which is interpreted as due to the loss of metals by supernovae winds and to differential gas outflows.

To point out the relevance of this type of study for the formation of dwarf irregular galaxies and the evolution of the LG, I will also discuss our results for other nearby dwarf galaxies, in terms of the metallicity-luminosity relationship of dwarf irregulars (dIrr) and spheroidals (dSph). We study this relation to test the proposition that dSph are formed through the removal of the gas in dIrr, either through ram pressure stripping, supernova driven winds or star formation.