Gas fraction vs. redshift. This figure shows the evolution of the gas mass fraction (i.e. M_gas/M_*) with the redshift. Black and red triangles represent the values derived for the E and W SPT0311-058 clumps, respectively, presented in Table 5. Red and black empty squares display the M_gas/M_* ratio obtained using the gas mass derived by Marrone et al. (2018) and the stellar masses computed in this work via SED fitting (see Sect. 4.1) for the E and W galaxies, respectively. For comparison, galaxies at intermediate redshifts (z ∼ 1–3) from the ASPECS 1.2 mm sample presented in Aravena et al. (2020) are included. The higher redshift range (z ∼ 4.4–6) is covered with the ALPINE sample, for which we calculate the gas mass following the L_CII − M_gas relation introduced by Zanella et al. (2018). The black continuum, dashed, and dashed–dotted lines show the gas fraction evolution following Liu et al. (2019) for a galaxy with a stellar mass of M_* = 5×10¹⁰ M_⊙ and an SFR that is one, three, and ten times the one expected for the SFR main sequence, respectively.