Table 1.

Results of analysis of skewness (ANSKEW; see Wang 2001) based on 33 families of New World birds, showing the between- and within-clade components (SCB and SCW), heteroscedasticity (SCH) and the percentage of variation along environmental state space that can be explained by tropical diversification and by adaptive radiation. (All the adaptive radiation components were significant at p<0.0001 according to 10 000 bootstrap resamples, because tropical diversification components are always lower than the expected value of ca 0.995.)

environmental dimension	SCB	SCW	SCH	tropical diversification	adaptive radiation
AET	0.223	0.476	0.300	47.64	52.36
TEMP	0.222	0.431	0.346	43.13	56.86
RELEV	0.002	0.849	0.153	84.96	15.04
NPP	0.149	0.709	0.141	70.99	29.05