A1 Refereed original research article in a scientific journal
Rampant hybridization in an old tropical fern genus (Danaea, Marattiaceae)
Authors: Keskiniva, Venni; Lehtonen, Samuli; Testo, Weston; Consortium GoFlag; Tuomisto, Hanna
Publisher: Wiley-VCH Verlag GmbH & Co. KGaA
Publication year: 2025
Journal: Taxon
ISSN: 0040-0262
eISSN: 1996-8175
DOI: https://doi.org/10.1002/tax.13315
Web address : https://doi.org/10.1002/tax.13315
The number of hybrids has been reported to be lower in tropical than temperate ferns, but patterns of hybridization are poorly known in the tropics. We examine hybridization in the Neotropical fern genus Danaea (Marattiaceae) using a phylogenomic approach with single or low-copy nuclear and chloroplast loci and haplotype phasing. We find a high hybridization rate of 10%–18% for Danaea, similar to the rates observed for temperate ferns. We find further evidence for the previously proposed low reproductive barriers in ferns, enabling hybridization and even the production of hybridization-derived species between lineages separated possibly as far back as the Cretaceous. We found that Danaea trifoliata and D. wendlandii are fertile, hybridization-derived species between lineages diverged potentially 14–72 million years ago (mya) and 23–62 mya, respectively. We also confirm that the previously recognized species D. ×ushana is a likely sterile hybrid between D. simplicifolia (D. subg. Arthrodanaea) and D. nigrescens (D. subg. Danaea), which diverged potentially 27–83 mya. We find that hybridization may function as a homogenizing force in Danaea, as the subgenus with the highest signals for hybridization (D. subg. Arthrodanaea) also has the fewest species that are the least morphologically and genetically diverged. We describe a new hybrid between D. wendlandii (D. subg. Holodanaea) and D. subg. Danaea as D. ×deltoidea.
Funding information in the publication:
We thank the M herbarium for loans and the CR herbarium for pictures of their specimens. VK has been funded by the Graduate School of the University of Turku, Turku University Foundation, TOP-Säätiö, and the Danish National Research Foundation (grant DNRF179 to HT). Funding for sequencing and data analyses was provided to the GoFlag (Genealogy of Flagellate Plants) Consortium by NSF DEB-1541506. Herbarium specimens have been collected and sequenced during several projects funded by the Academy of Finland (e.g., grants 73416, 139959, 273737, and 351460 to HT). Analyses of the multi-locus data were done on the computing facilities of the CSC-IT Center for Science Ltd (csc.fi). An earlier version of this article is part of the Ph.D. thesis of VK.