High density, genome-wide markers and intra-specific replication yield an unprecedented phylogenetic reconstruction of a globally significant, speciose lineage of Eucalyptus

• A robust phylogeny for a globally significant Eucalyptus lineage is constructed.
• Genome-wide markers and an unprecedented scale of sampling (540 samples covering 185 taxa) are used.
• Inconsistencies between morphological treatments and the molecular phylogeny are revealed at all taxonomic levels.
• Incomplete speciation, hybridisation and morphological convergence have impacted this lineage.
• Recommendations for taxonomic revision are given.

We used genome-wide markers and an unprecedented scale of sampling to construct a phylogeny for a globally significant Eucalyptus lineage that has been impacted by hybridisation, recent radiation and morphological convergence. Our approach, using 3109 DArT markers distributed throughout the genome and 540 samples covering 185 terminal taxa in sections Maidenaria, Exsertaria, Latoangulatae and related smaller sections, with multiple geographically widespread samples per terminal taxon, produced a phylogeny that largely matched the morphological treatment of sections, though sections Exsertaria and Latoangulatae were polyphyletic. At lower levels there were numerous inconsistencies between the morphological treatment and the molecular phylogeny, and taxa within the three main sections were generally not monophyletic at the series (at least 62% polyphyly) or species (at least 52% polyphyly) level. Some of the discrepancies appear to be the result of morphological convergence or misclassifications, and we propose some taxonomic reassessments to address this. However, many inconsistencies appear to be the products of incomplete speciation and/or hybridisation. Our analysis represents a significant advance on previous phylogenies of these important eucalypt sections (which have mainly used single samples to represent each species), thus providing a robust phylogenetic framework for evolutionary and ecological studies.

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