Genotyping-by-Sequencing and Morphology Revealed the Role of Polyploidization and Hybridization in the Diversification of the L. Complex of Section (Juss.) DC. (Asteraceae)

Hybridization and polyploidy are major drivers of plant evolution. In (Asteraceae), both mechanisms are frequent and lead to reticulate evolutions. However, in the Western Mediterranean section, studies are scarce. In this section, forms a complex including four European diploid and one Moroccan autotetraploid subspecies, an allopolyploid, and hybrids among them. Here, we aimed to delimit the different taxa, identify any introgressions, and discuss their evolutionary history. Samples of all taxa were analysed using 1688 SNPs obtained through GBS and were morphologically characterized. Three genetically well-differentiated clusters were observed, corresponding to the allopolyploid , the diploid and the cryptic autotetraploid ssp. , which is proposed to be considered as a species. showed a high isolation by distance, a greater morphological variability, and a lack of interspecific gene flow. Diploid and autotetraploid individuals were morphologically similar, and some introgressions were detected in Southern Spain, where new forms may promote diversification. This gene flow might have taken place during the Messinian and before autopolyploidization occurred in Morocco. In the complex, current interspecific barriers are strong, while polyploidization may provide a better adaptation to drier environments.