ChromEvol: Assessing the Pattern of Chromosome Number Evolution and the Inference of Polyploidy along a Phylogeny

We announce the release of chromEvol version 2.0, a software tool for inferring the pattern of chromosome number change along a phylogeny. The software facilitates the inference of the expected number of polyploidy and dysploidy transitions along each branch of a phylogeny and estimates ancestral chromosome numbers at internal nodes. The new version features a novel extension of the model accounting for general multiplication events, other than doubling of the number of chromosomes. This allows the monoploid number (commonly referred to as x, or the base-number) of a group of interest to be inferred in a statistical framework. In addition, we devise an inference scheme, which allows explicit categorization of each terminal taxon as either diploid or polyploid. The new version also supports intraspecific variation in chromosome number and allows hypothesis testing regarding the root chromosome number. The software, alongside a detailed usage manual, is available at http://www.tau.ac.il/∼itaymay/cp/chromEvol/.