Background: The nonparametric bootstrap is widely used to measure the branch support of phylogenetic trees.
However, bootstrapping is computationally expensive and remains a bottleneck in phylogenetic analyses. Recently,
an ultrafast bootstrap approximation (UFBoot) approach was proposed for maximum likelihood analyses. However,
such an approach is still missing for maximum parsimony.
Results: To close this gap we present MPBoot, an adaptation and extension of UFBoot to compute branch
supports under the maximum parsimony principle. MPBoot works for both uniform and non-uniform cost matrices.
Our analyses on biological DNA and protein showed that under uniform cost matrices, MPBoot runs on average 4.7
(DNA) to 7 times (protein data) (range: 1.2–20.7) faster than the standard parsimony bootstrap implemented in
PAUP*; but 1.6 (DNA) to 4.1 times (protein data) slower than the standard bootstrap with a fast search routine in
TNT (fast-TNT). However, for non-uniform cost matrices MPBoot is 5 (DNA) to 13 times (protein data) (range:0.3–63.
9) faster than fast-TNT. We note that MPBoot achieves better scores more frequently than PAUP* and fast-TNT.
However, this effect is less pronounced if an intensive but slower search in TNT is invoked. Moreover, experiments
on large-scale simulated data show that while both PAUP* and TNT bootstrap estimates are too conservative,
MPBoot bootstrap estimates appear more unbiased.
Conclusions: MPBoot provides an efficient alternative to the standard maximum parsimony bootstrap procedure. It
shows favorable performance in terms of run time, the capability of finding a maximum parsimony tree, and high
bootstrap accuracy on simulated as well as empirical data sets. MPBoot is easy-to-use, open-source and available at
http://www.cibiv.at/software/mpboo