A comprehensive phylogenomic framework for cycads (Cycadales)

Here we present a time-calibrated phylogeny of 346 cycad accessions, covering ≈86% of the 380 accepted species, across all 10 extant genera, inferred from 1,409 single-copy nuclear loci (411,345 amino acid sites) derived from transcriptome and genome data. The maximum likelihood phylogeny was inferred using a partitioned analysis, with branch support assessed via ultrafast bootstrap (UFBoot2), and concordance evaluated using gene concordance factors (gCF) and site concordance factors (sCF), representing gene- and site-level support, respectively. Divergence times were estimated using penalized likelihood (TreePL) with 12 calibration constraints, and 95% confidence intervals were derived from 100 gene-wise bootstrap replicates. Bootstrap support is high (70% of nodes ≥95%), but gene concordance factors are low (median gCF = 3.2%), a pattern consistent with limited phylogenetic signal per locus rather than strong support for alternative topologies. We provide the phylogram, timetree, all 1,409 gene trees, the concatenated alignment with