Sequential colonization events with restricted gene flow in a widespread European carnation species

The key questions relating to the evolutionary processes underlying plant colonization success pertain to the geographic origin of the source population(s), the location of the migration routes, the extent to which genetic diversity is reduced via founder effects, and the extent of gene flow among populations during expansion. However, these questions must still be addressed for perennial herbaceous plants with large geographic distributions. We investigated the colonization history of Dianthus carthusianorum (the Carthusian Pink), one of the most widespread European carnation species. We called genome-wide 236,964 SNPs from a large sample across the D. carthusianorum distribution range, and used up-to-date population genomics approaches (approximate Bayesian computation Random-Forest method, ABC-RF) to infer population demographic history. Spatial genetic structure and diversity analyses and demographic inferences indicated successive East-West colonization events by the Carthusian Pink. ABC-RF also revealed gene flow during colonization, but only among geographically close populations. This study provides important insights into the colonization processes of herbaceous perennial species belonging to one of Europes most diverse plant genera.