Phylogenetic logistic regression parameter estimates for the effect of colony size on the social structure of corbiculate bees (b1). (a) Phylogenetic signal.

aParameters of logistic regression and standard errors of the estimates were obtained using the GEE approximation (see Ives & Garland, 2010).bParametric bootstrapping was performed by simulating 2000 data sets to obtain confidence intervals. Parametric bootstrapping was also used to test the null hypotheses that there is no phylogenetic signal in the residuals (H0: a = −4, 1-tailed test) and that the regression coefficients equal 0 (H0: bi = 0, 2-tailed tests).