A splendid banana enigma: Phylogenomic assessment of Vietnamese Musa splendida and Musa viridis populations shows that they are conspecific

TL;DR

This study shows that two banana species from Vietnam, Musa splendida and Musa viridis, are actually the same species based on genetic and population data.

Contribution

The study uses high-throughput sequencing to resolve a taxonomic debate and proposes synonymy between two Musa species.

Findings

Genetic clustering grouped plants by population origin, not by species identity.

M. viridis plants were more closely related to M. splendida from the same region than to other M. viridis plants.

An isolation-by-distance pattern was observed among populations.

Abstract

Species delimitation is essential to study and conserve biological diversity. It is traditionally based on morphological trait variation observed in one or a few specimens. Nevertheless, such assessments may not sufficiently take intraspecific trait variation into account, misidentifying morphotypes as separate species. The use of high-throughput sequencing data alongside morphological data in taxonomic studies may substantially improve the accuracy of taxonomic assessments. The Musa genus, commonly known for comprising the wild relatives of banana varieties, consists of about seventy described species. However, the taxonomic status of multiple Musa species is uncertain due to typification errors and the lack of high-quality specimens. The species M. splendida and M. viridis from northern Viet Nam only substantially differ from each other in the color of their male flower bracts, which is red to pinkish-red in M. splendida and pink in M. viridis. Consequently, their taxonomic status as separate species has been debated. Here, we studied the genetic relationships between 121 M. splendida and M. viridis plants using high-throughput sequencing data (DArTseq) in which we identified 51,188 single nucleotide polymorphisms. We found that individuals genetically clustered in a principal component analysis (6 clusters), fastStructure analysis (four groups), and ASTRAL-III consensus phylogenetic tree (nine clades) based on their population origin rather than by their taxon identity. In addition, a strong signal for an isolation-by-distance pattern between populations was observed. Plants identified as M. viridis were more closely related to M. splendida plants from the same region than to M. viridis plants from other regions. Hence, we propose to treat M. viridis as a synonym of M. splendida.

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