The existence of eight basic diploid lineages explains the origin of seven Eurasian polyploid groups within the Chenopodium album aggregate and brings evidence of a nearly unlimited number of subgenomic combinations. The supposed promiscuity generated new species wherever different diploid lineages met each other and gave rise to tetraploid species or whenever they met other tetraploid species to produce hexaploid species throughout their evolutionary history. Finally, we unravelled a surprisingly simple scheme of polyploid species formation within the C. album aggregate. We determined seven groups of polyploid species differing in their origin in either Eurasia or Africa and convincingly demonstrated that (1) all Chenopodium polyploid species under study are of allopolyploid origin, (2) there are eight major monophyletic evolutionary lineages represented by extant or extinct/unknown diploid taxa, (3) those monophyletic lineages represent individual subgenomes, (4) hybridization among the lineages created seven subgenomic combinations of polyploid taxa, (5) taxa represented by particular subgenome combinations were further subjected to diversification, and (6) the majority of species are relatively young, not exceeding the age of the Quaternary period.
Mandák B., Krak K., Vít P., Lomonosova M. N., Belyayev A., Habibi F., Wang L., Douda J. & Štorchová H. (2018): Hybridization and polyploidization within the Chenopodium album aggregate analysed by means of cytological and molecular markers. Molecular Phylogenetics and Evolution 129: 189–201.