Deriving Phylogenies from Synthesis Trees R package rtrees version 2.0.2 Provides tools to derive species-level phylogenies from large synthesis mega-trees for a wide range of taxonomic groups, including plants, birds, mammals, amphibians, reptiles, fish, bees, butterflies, and sharks. When a queried species is absent from the mega-tree, it is grafted onto the tree using one of two placement strategies: attachment at the basal node of the most closely related genus or family ('at_basal_node'), or random attachment below that basal node with probability proportional to branch length ('random_below_basal'). See Li (2023) <doi:10.1111/ecog.06643> for details. Multiple species from a genus not represented in the mega-tree are placed as a polytomy to preserve clade coherence. The package interfaces with the 'megatrees' data package, which bundles or downloads on demand curated mega-trees. Users can also provide their own mega-trees. Software Depends: R (>= 3.5.0) Imports: ape, tidytree, dplyr, tibble, utils, castor, furrr, future, megatrees (>= 0.1.3), fastmatch, data.table, Rcpp LinkingTo: Rcpp Suggests: knitr, rmarkdown, testthat, piggyback, R.rsp, ggplot2 Daijiang Li <daijianglee@gmail.com> Comprehensive R Archive Network (CRAN) Daijiang Li [aut, cre] (ORCID: <https://orcid.org/0000-0002-0925-3421>) GPL-3 2026-06-11 application/tgz https://CRAN.R-project.org/package=rtrees doi:10.32614/CRAN.package.rtrees