Phylogeny and biogeography of the fern genus Hymenasplenium (Aspleniaceae), with special reference to island speciation

Abstract

Although considerable progress has recently been made in the phylogeny of Hymenasplenium, the genus remains poorly investigated; specifically, the diversification and historical biogeography of the genus have been little studied. Here, we infer an updated plastid DNA phylogeny and the first large-scale nuclear DNA phylogeny to understand the biogeography of the genus. The plastid phylogeny includes 312 accessions from across the genus′ distribution range (ca. 121% increase of the latest sampling), with special attention paid to island accessions from 14 Indian Ocean and Pacific islands, whereas the nuclear phylogeny includes 161 accessions of the Afro–Eurasian species. We identify one new major clade and two new subclades. Reticulate evolution was revealed both among subclades and among species in the Afro–Eurasian. Our divergence-time analyses show that most of the extant species diversity has arisen from diversification after the Oligocene despite a Cretaceous origin of the genus. Ancestral area reconstruction revealed that vicariance likely played a major role in building biogeographic patterns at deep evolutionary scales (the Afro–Eurasian clade and the American clade) in Hymenasplenium, while the intercontinental disjunctions within the Afro–Eurasian clade among Asia, Africa, and Oceania might have resulted from frequent long-distance dispersal events from Asia to Oceania and Africa.

Keywords

Asplenium / boreal-tropics / dispersals / fern evolution / island biogeography / LEAFY gene

RIGHTS & PERMISSIONS

2025 Institute of Botany, Chinese Academy of Sciences.