Nat. Genet. 47, 65–72 (2015); published online 24 November 2014; corrected after print 9 January 2015; corrected after print 6 February 2015

In the version of this article initially published, the legend for Figure 1b referred to red arrows indicating the inferred divergence dates. No arrows are depicted in the figure, so this sentence has been removed from the figure legend in the HTML and PDF versions of the article.