Other information is also surely helpful and application-specific. One example involving human hosts quantifies the availability of motorized transportation, such as air flights, between sites. We explore the utility BSSVS and distance-informed priors in our phylogeographic models. Bayes factor test of significant diffusion rates. The Bayes factor (BF) for a particular rate k contributing to the migration graph is the posterior odds that rate k is non-zero divided by the equivalent prior odds,