Interpreting the modern distribution of Myrtaceae using a dated molecular phylogeny

Area of Science:

• Evolutionary biology
• Phylogenetics
• Biogeography

Background:

• The angiosperm family Myrtaceae, with taxa across southern continents, is hypothesized to have a Gondwanan origin.
• Disjunct transoceanic distributions in Myrtaceae suggest vicariance or long-distance dispersal and establishment (LDDE).
• Some Myrtaceae groups inhabit Pacific islands with complex geological histories.

Purpose of the Study:

• To test hypotheses of vicariance and LDDE in Myrtaceae evolution.
• To estimate divergence times and reconstruct the biogeographic history of the family.
• To investigate the drivers of transoceanic distribution patterns within Myrtaceae.

Main Methods:

• Molecular clock dating using 12 fossil calibrations.
• Phylogenetic analysis of 88 genera and 202 species representing Myrtaceae subfamilies and tribes.
• Reconstruction of divergence times and ancestral areas.

Main Results:

• Myrtaceae was reconstructed as Gondwanan in origin.
• Of 22 disjunct sister groups, 13 are attributed to LDDE, 6 to vicariance, and 3 to overland dispersal.
• LDDE events, primarily in fleshy-fruited taxa, predominantly occurred post-Miocene, while vicariance events predate the Late Eocene.

Conclusions:

• Long-distance dispersal and establishment (LDDE) is the primary driver of modern transoceanic distributions in Myrtaceae.
• Vicariance events played a significant role in earlier diversification before the Late Eocene.
• The distributions of isolated taxa like Arillastrum, Myrtus, and Tepualia require further investigation with fossil and geological data.