Genome size of grass Festuca mountain species from the Pyrenees and Prepyrenees: variation, evolution and new assessments

Abstract

Abstract Festuca is one of the most ecologically and economically important genera of temperate grasses. Species of its main subgenus Festucaare common components of cool-seasonal pastures and are especially frequent in mountainous areas, where there are often several morphologically similar species that grow in the same or comparable habitats and sometimes live in sympatry. Nuclear DNA assessments by flow cytometry can be used to identify taxa and uncover new ploidy levels in species complexes for which previous chromosome counts and genome sizes are known. 2C values of newly studied Pyrenean and Prepyrenean Festucasubgen. Festuca sects. Eskia, Festuca and Aulaxyperspecies range from 4.41 to 16.36 pg and include 2x, 4x, 6x and 8x ploidy levels. 2C mean values of diploids and polyploids are larger in the species of the more ancestral F. sect. Eskia group showing a decreasing trend in the species of the more recently evolved F. sects. Festuca and Aulaxyperlineages. Monoploid genome sizes of high polyploid Aulaxyper taxa are among the smallest of the three Festuca sections, corroborating previous findings. Our analysis provides new genome size values and inferred ploidy levels for hexaploid F. heteromallaand octoploid F. trichophylla and highlights the genomic and ecological differentiation of tetraploid F. gautieri susbsp. gautieri from diploid F. gautierisubsp. scoparia.