  We investigated testing the likelihood of a phylogenetic tree by comparison
to its subtree pruning and regrafting (SPR) neighbors, with or without
re-optimizing branch lengths. This is inspired by aspects of Bayesian
significance tests, and the use of SPRs for heuristically finding maximum
likelihood trees. Through a number of simulations with the Jukes-Cantor model
on various topologies, it is observed that the SPR tests are informative, and
reasonably fast compared to searching for the maximum likelihood tree. This
suggests that the SPR tests would be a useful addition to the suite of existing
statistical tests, for identifying potential inaccuracies of inferred
topologies.
