Target enrichment and transcriptome sequencing of multiple species of Moehringia (Caryophyllaceae) Raw sequence reads
Premise of the study:The origin of endemic species in the European Alps is commonly attributed to the climatic oscillations of the Quaternary. Moehringia sect. Moehringia, with 12 of 15 species endemic to the Alps and mostly of regional distribution in well-known glacial refugia, is a prime system for investigating the diversification of a lineage from the Alps.Methods:We used all species of this lineage, most represented by multiple accessions, and a target enrichment approach with baits specifically designed for Moehringia, to obtain a phylogenetic tree based on 829 nuclear loci. We also dated the phylogenetic tree with a molecular clock approach.Key results:Most species originated in the Quaternary. Four regionally distributed species (M. intermedia, M. markgrafii, M. papulosa, M. tommasinii), all nested within the widespread M. muscosa, were found to be between 1.37 and 0.25 Ma old. Moehringia muscosa and the four species derived from it differ in habitat and leaf succulence, and glaucousness.Conclusions:As the widespread species has not coalesced into monophyly, and the regionally distributed species have evolved in glacial refugia, we consider speciation in this lineage to be incomplete and climate-driven. Divergence in habitat and leaf morphology between the widespread and the derived species may suggest a role of adaptive evolution.