Table 1 Results from BBMV analysis including gonadal sex allocation of 120 species. For each model, we give the Brownian motion variance (σ2), and the values of the parameters of the polynomial terms used to shape the macroevolutionary landscape (ax4 + bx2 + cx) and the AIC weights. Values in brackets are the bounds of the 95% CI. Note, that parameter b is negative for the BBMV model, which results in a landscape with two peaks