Population structure and phylogeography of Elymus mutabilis and its genetic relationships with E. transbaicalensis (Poaceae)

Abstract

Elymus mutabilis is a morphologically diverse species in the Poaceae family growing in Eurasia from northern Europe to far east Russia and southwards to central Asia. Elymus transbaicalensis occurs in similar habitats and is considered closely related to E. mutabilis and sometimes even referred to as a subspecies or synonym. Based on high similarity in morphology and habitat, molecular studies are needed to establish whether E. mutabilis and E. transbaicalensis can be considered as two distinct species. Thus, the objective of this study was to study diversity, relationships among populations and the phylogeographical structure of E. mutabilis and E. transbaicalensis using genotyping‐by‐sequencing (GBS). In total 68 individuals of E. mutabilis were sampled from 18 populations collected from northern Europe, central Asia and far east Russia, representing the central and two peripheral parts of the natural distribution of the species. The results reveal a clear distinction between E. mutabilis and E. transbaicalensis and no introgression. The phylogeographic structure of E. mutabilis follows the geographical distribution of the species. Populations from northern Europe, southern Siberia and far east Russia together form a clade separated from the peripheral populations in central Asia, indicating a common ancestry of the latter. Phylogenetic analyses revealed a radiation pattern among populations in northern Europe indicating a founding followed by rapid dispersal.