A dated phylogeny of Argophyllaceae (Asterales) is consistent with spread by long-distance dispersal

ABSTRACT

Argophyllaceae is a small eudicot family of trees and shrubs of south-western Pacific distribution, comprising two genera: Corokia and Argophyllum. The phylogeny of Corokia, which contains six species, has attracted little attention so far, the genus being usually represented by a single species in studies looking at relationships at higher taxonomic levels. Here we bridge this knowledge gap with a complete phylogeny of the genus based on whole-plastid DNA sequences. We also investigated nuclear ribosomal DNA markers, which yielded a poorly supported phylogeny. Comparing fossil-calibrated and biogeographic dating approaches, we conclude that extant Argophyllaceae species are probably not Gondwanan relicts, the timing of their divergences being better explained by long-distance dispersal after the break-up of Gondwana than by vicariance. The high level of endemicity of the species of Corokia prevents the reconstruction of a precise biogeographic history of the genus, but our phylogenies suggest that the genus originated in Australia, then about 3.5 My ago started dispersing eastwards into the Pacific towards its present-day distribution.

KEYWORDS:

• Argophyllum
• biogeographic calibration
• biogeography
• chloroplast DNA
• Corokia
• internal transcribed spacer
• next generation sequencing

Acknowledgements

The authors would like to thank Chris Lusk and two anonymous reviewers for commenting on the draft manuscript; the Direction de l’Environnement of the Province Sud of New Caledonia for local sampling permits and David Bruy, Vanessa Hequet, Sandrine Isnard and Hervé Vandrot for their help in preparing and conducting the sampling there; the Department of Conservation, Otari Native Garden, Ngāti Rangi and Mōkai Pātea for the sampling permits and agreements in New Zealand; Patricio Saldivia Perez for DNA samples; CHR, NOU, CANB, MEL, HO and P for leaf samples; Mary Korver (CHR) for assistance with herbarium loans.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research is supported by the Royal Society of New Zealand (Te Apārangi) [Marsden contract 16-UOW-029]; and the Faculty of Science and Engineering of the University of Waikato through FSEN Student Trust Fund [grant number # P102218 SoS/PG Support].