Towards a species-level phylogeny for Neotropical Myrtaceae: notes on topology and resources for future studies

Premise of the study: Increasingly complete phylogenies underpin studies in systematics, ecology, and evolution. Myrteae (Myrtaceae), with c. 2,500 species, is a key component of the exceptionally diverse Neotropical flora, but given its complicated taxonomy, automated assembling of molecular supermatrices from public databases often lead to unreliable topologies due to poor species identification. Methods: Here, we build a taxonomically verified molecular supermatrix of Neotropical Myrteae by assembling 3,954 published and 959 unpublished sequences from two nuclear and seven plastidial molecular markers. We infer a time calibrated phylogenetic tree that covers 712 species of Myrteae (c. 28% of the total diversity in the clade) and evaluate geographic and taxonomic gaps in sampling. Key results: The tree inferred from the fully concatenated matrix mostly reflects the topology of the plastid dataset and there is a moderate to strong incongruence between trees inferred from nuclear and plastid partitions. Large, species-rich genera are still the poorest sampled within the group. Eastern South America is the best-represented area in proportion to its species diversity, while Western Amazon, Mesoamerica, and the Caribbean are the least represented. Conclusions: We provide a time-calibrated tree that can be more reliably used to address finer-scale eco-evolutionary questions that involve this group in the Neotropics. Gaps to be filled by future studies include improving representation of taxa and areas that remain poorly sampled, investigating causes of conflict between nuclear and plastidial partitions and the role of hybridization and incomplete lineage sorting in relationships that are poorly supported.