MBASR: Workflow-simplified ancestral state reconstruction of discrete traits with MrBayes in the R environment

Ancestral state reconstruction (ASR) is a critical tool in comparative biology. Given a phylogenetic tree and observed trait states for taxa at the tree’s tips, ASR aims to model ancestral trait states at the tree’s internal nodes. Thus, the pattern, tempo, and frequency of a character’s evolution can be considered in a phylogenetic framework. Software programs that perform discrete trait ASR analyses are variably complex in terms of workflow steps, input formats, user interfaces, settings and execution commands, and the organization of output. MBASR (acronym for MrBayes Ancestral States with R ) is an R language toolkit that highly automates the ASR workflow and uses the machinery of the popular phylogenetics software MrBayes. Input data files are simple, analysis can be setup and run with a single R function, and statistical output is concisely organized and immediately interpretable. Use requires minimal knowledge of the most basic R commands and no experience with the MrBayes program. The MBASR toolkit can be freely downloaded from GitHub.