Comment on "An update of Wallace's zoogeographic regions of the world".

Holt et al. (Report, 4 January 2013, p. 74) propose substantial modifications of Wallace's long-standing zoogeographic regions based on clustering of a pairwise similarity matrix of vertebrate assemblages. We worry about their compromised use of phylogenies and show that a fundamental point of their analysis--i.e., the delineation of new realms--is only weakly supported by their results and conceptually flawed.