Nature 405 , 1052 - 1055 (2000).

There was an error in the geographical character-state mapping in this paper. The authors inadvertently reported the values corresponding to mapping these characters onto the tree in an unordered manner. Correctly ordering the character-state changes according to the ‘express-train’ model does not change the main conclusion of the paper: the express-train model fits much better than would be expected owing to chance. The correct fit is 18 steps, and the fit of the randomly assigned character states now ranges from 95 to 122 (mean 108.4, s.d. 5.1).