Genome size variations in polyploid Allium oleraceum

The occurrence and extent of genome size variation below the species level are currently poorly analysed. Using flow cytometry, Duchoslav et al. demonstrate complex patterns of holoploid and monoploid genome size variation both within and between six ploidy levels of Allium oleraceum (Alliaceae) for 114 populations across the European continent. They consider that these are most likely the result of several interacting factors, including different evolutionary origins of cytotypes via hybridization of parental combinations with different genome sizes in the south-western and south-eastern part of Europe, introgression between cytotypes, and anthropic dispersal. The role of broad-scale environmental variables in shaping the genome size is probably of minor importance in A. oleraceum.