A phylogenetic study of the tribe Antirrhineae: Genome duplications and long-distance dispersals from the Old World to the New World.

PREMISE OF THE STUDY: Antirrhineae is a large tribe within Plantaginaceae. Mostly concentrated in the Mediterranean Basin, the tribe members are present both in the Old World and the New World. Current Antirrhineae phylogenies have different views on taxonomic relationships, and they lack homogeneity in terms of geographic distribution and ploidy levels. This study aims to investigate the changes in the chromosome numbers along with dispersal routes as definitive characters identifying clades.

METHODS: With the use of multiple DNA regions and taxon sampling enriched with de novo sequences, we provide an extensive phylogeny for Antirrhineae. The reconstructed phylogeny was then used to investigate changes in ploidy levels and dispersal patterns in the tribe using ChromEvol and RASP, respectively.

KEY RESULTS: Antirrhineae is a monophyletic group with six highly supported clades. ChromEvol analysis suggests the ancestral haploid chromosome number for the tribe is six, and that the tribe has experienced several duplications and gain events. The Mediterranean Basin was estimated to be the origin for the tribe with four long-distance dispersals from the Old World to the New World, three of which were associated with genome duplications.

CONCLUSIONS: On an updated Antirrhineae phylogeny, we showed that the three out of four dispersals from the Old World to the New World were coupled with changes in ploidy levels. The observed patterns suggest that increases in ploidy levels may facilitate dispersing into new environments.