Extended Data Fig. 7: Ancestral-state reconstruction and statistical tests of a correlation between soaring flight and the SPD.

a, The inferred evolutionary histories of soaring flight (left) and the SPD (right), with pie charts illustrating the posterior probability (PP) of a character-state transition for branches with probabilities >0.1. b, AIC values associated with Pagel’s¹⁸ test of discrete character correlation under four competing models. The best-fit model is one in which the evolution of the SPD depends on the presence of soaring flight and character transition rates are asymmetrical (ARD_dep); in order of decreasing fit, the remaining models include: dependent character evolution with symmetrical transition rates (SYM_dep); independent character evolution with symmetrical transition rates (SYM_dep); and independent character evolution with asymmetrical transition rates (ARD_indep). c, Posterior distribution of the value of the correlation coefficient (r) for Felsenstein’s¹⁹ implementation of the threshold model. The 95% highest posterior density (marked by red dashed lines) is well-removed from zero.