Top: relationship between the mass of the regions [M_⊙] and the exponent of the exponential fit to the DGMFs (α_exp). Black solid line shows the best fit to the data and the shaded region shows its σ error. The dotted and dashed lines show the best fit when the most massive H ii  regions are removed. Colors indicate the evolutionary class of each point as indicated. Middle: relationship between mass of the regions and the slope of the power-law range of the DGMFs. Black line shows the best fit to the data and the shaded region shows its σ error. Bottom: relationship between the mean gas mass surface density of the MCs, Σ_mass, and the dense gas mass fraction of gas, . The crosses show the f_DG obtained integrating the exponential regime of the DGMFs of each region in the range A_V = 0−7 mag (see third paragraph in Sect. 4.2). Black line shows a linear fit to the data in the range Σ_mass = 50−200 M_⊙ pc^-2. Vertical dashed line at Σ_mass = 116 M_⊙ pc^-2 (Lada et al. 2010, 2012) indicates the threshold for the dense gas.