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Molecular data of cryptic species in the Sphagnum magellanicum complex (Bryophyta) in North America

Nieto-Lugilde, Marta1

Published Jun 10, 2024 on Dryad. https://doi.org/10.5061/dryad.37pvmcvtk

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Abstract

Sphagnum magellanicum (Sphagnaceae, Bryophyta) has been considered to be a single semi-cosmopolitan species, but recent molecular analyses have shown that it comprises a complex of at least seven reciprocally monophyletic groups, that are, however, difficult or impossible to distinguish morphologically. Newly developed barcode markers and RADseq analyses were used to identify species among 808 samples from 119 sites. Molecular approaches are used here to assess the geographic ranges of four North American species, the frequency at which they occur sympatrically, and ecological differentiation among them. Microhabitats were classified with regard to hydrology and shade. Hierarchical Modelling of Species Communities was used to assess climate variation among the species. Climate niches were projected back to 22,000 years bp to assess the likelihood that the North American species had sympatric ranges during the late Pleistocene. The species exhibit parallel morphological variation, making it extremely difficult to distinguish phenotypically. Two to three species frequently co-occur within peatlands. They have broadly overlapping micro-habitat and climate niches. Barcode- versus RADseq-based identifications were in conflict for 6% of the samples, and always involved S. diabolicum vs. S. magniae. These species co-occur within peatlands at scales that could permit interbreeding, yet they remain largely distinct genetically and phylogenetically. The four cryptic species exhibit individualistic geographic and ecological patterns. Conflicting identifications from barcode vs. RADseq analyses for S. diabolicum versus S. magniae could reflect incomplete speciation or hybridization. They comprise a valuable study system for additional work on climate adaptation.