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Abstract— Like many fern lineages comprising reticulate species complexes, Polypodium s.s. (Polypodiacaeae) has a history shaped by rapid diversification, hybridization, and polyploidy that poses substantial challenges for phylogenetic inference with plastid and single-locus nuclear markers. Using target capture probes for 408 nuclear loci developed by the GoFlag project and a custom bioinformatic pipeline, SORTER, we constructed multi-locus nuclear datasets for diploid temperate and Mesoamerican species of Polypodium and five allotetraploid species belonging to the well-studied Polypodium vulgare complex. SORTER employs a clustering approach to separate putatively paralogous copies of targeted loci into orthologous matrices and haplotype phasing to infer allopolyploid haplotypes across loci, resulting in datasets amenable to both concatenated maximum likelihood and multi-species coalescent phylogenetic analyses. By comparing phylogenies derived from maximum likelihood and multi-species coalescent analyses of unphased and phased datasets, as well as evaluating discordance among gene trees and species trees, we recover support for incomplete lineage sorting within Polypodium s.s., novel relationships among diploid taxa of the Polypodium vulgare complex and its Mesoamerican sister clade, and the placement of several Polypodium species within other genera. Additionally, we were able to infer well-supported phylogenies that identified the hypothesized progenitors of the allotetraploid species, indicating that SORTER is an effective and accurate tool for reconstructing homeolog haplotypes of allopolyploids in fern taxa and other non-model organisms from target capture data. 

Green plants (Viridiplantae) include around 450,000–500,000 species of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida), including green plants (Viridiplantae), glaucophytes (Glaucophyta) and red algae (Rhodophyta). Our analysis provides a robust phylogenomic framework for examining the evolution of green plants. Most inferred species relationships are well supported across multiple species tree and supermatrix analyses, but discordance among plastid and nuclear gene trees at a few important nodes highlights the complexity of plant genome evolution, including polyploidy, periods of rapid speciation, and extinction. Incomplete sorting of ancestral variation, polyploidization and massive expansions of gene families punctuate the evolutionary history of green plants. Notably, we find that large expansions of gene families preceded the origins of green plants, land plants and vascular plants, whereas whole-genome duplications are inferred to have occurred repeatedly throughout the evolution of flowering plants and ferns. The increasing availability of high-quality plant genome sequences and advances in functional genomics are enabling research on genome evolution across the green tree of life.