Estimating the Optimal Number of Migration Edges from 'Treemix' R package OptM version 0.1.9 The popular population genetic software 'Treemix' by 'Pickrell and Pritchard' (2012) <DOI:10.1371/journal.pgen.1002967> estimates the number of migration edges on a population tree. However, it can be difficult to determine the number of migration edges to include. Previously, it was customary to stop adding migration edges when 99.8% of variation in the data was explained, but 'OptM' automates this process using an ad hoc statistic based on the second-order rate of change in the log likelihood. 'OptM' also has added functionality for various threshold modeling to compare with the ad hoc statistic. Software Depends: R (>= 3.2.2) Imports: SiZer (>= 0.1-4), stats, grDevices Robert Fitak <rfitak9@gmail.com> Comprehensive R Archive Network (CRAN) Robert Fitak [aut, cre] GPL (>= 2) 2025-05-21 application/tgz https://CRAN.R-project.org/package=OptM doi:10.32614/CRAN.package.OptM