Summarizing posterior location uncertainty. An important statistical question asks to what extent the data inform our inference when fitting different phylogeographic models. A model of low statistical power makes poor use of the information in the data, while a successful model exploits this information to generate posterior distributions that are maximally different from prior beliefs. One primary outcome of a Bayesian phylogeographic study is the marginal posterior distribution of the root location Pr X root jX, Y ð Þ . We calculate the Kullback-Leibler (KL) divergence [54] from the root location prior P to summarize this information gain,