Phenotypic and genetic variation in natural populations of Festuca rubra s.l. in Europe

Background: Phenotypic variation within species challenges the identification of meaningful taxonomic units and the quantification of evolutionarily relevant biodiversity.

Aims: We studied usefulness of the present taxonomic classification of species and subspecies within Festuca rubra complex.

Methods: We categorised F.rubra s.l. plants collected from natural populations across Europe such as the endemic species of F. rothmaleri and F. rubra subspecies (subsp. rubra and arctica) or between-subspecies hybrids (arctica × rubra). The plants were grown in a common garden, which was followed by an examination of variation in regard to 17 morphological traits, ploidy levels, nuclear ribosomal DNA, and chloroplast DNA.

Results: Phenotypic and cpDNA markers demonstrated stronger differentiation between geographic regions than between species or subspecies. Of the morphological traits, only lemma hairiness distinguished between F.rubra subspecies. Ploidy level varied within the F. rothmaleri and F.rubra subspecies. cpDNA and nrDNA markers showed no genetic differentiation among the F. rubra subspecies and their hybrids but clustered F. rubra taxa and F.rothmaleri as separate groups. Several additive polymorphic sites in nrDNA sequences indicated hybridisation in the F. rubra taxa.

Conclusion: Commonly used traits may not be reliable in determining evolutionary relevant taxonomic entities within F.rubra complex.