The genus has undergone a major recircumscription since the first molecular studies of the group were performed both plastid and nuclear ribosomal markers showed that it had been polyphyletic. Furthermore, it is not uncommon for single species to have multiple ploidy levels. Wolf have been reported to have dodecaploid (12 x) populations. According to the Chromosome Counts Database only a few species seem to be exclusively diploid, e.g. , is an example of a genus in Rosaceae with mixed ploidy levels. Some, as for instance Acaena L., Alchemilla L. Chromosome counting data, summarized by Vamosi and Dickinson, suggest that around half of the family’s genera include at least one polyploid species. The rose family (Rosaceae Juss.) is well known for its many polyploid taxa, and there seem to have been a large number of independent auto- and allopolyploidization events during its evolutionary history. This may create a new, independently evolving, lineage that could thus be regarded as a new species. A doubling of the chromosomes can make a sterile hybrid fertile and cause a reproductive barrier between individuals of the new genomic state and the old state. ![]() Two main types of polyploidization are recognized autopolyploidization, where the duplication occurs within a single species, and allopolyploidization, where the duplication occurs in combination with hybridization between two different species. This phenomenon is common throughout the vascular plants, where genome duplications can be found from the ferns and lycopods, to the asterids. Sometimes, however, new species evolve within a relatively short period of time through polyploidization. The evolution of species is usually considered to be a slow process, working over thousands or even millions of years. To better estimate when and where these hybridizations occurred, other Argentea, Ivesioid and Rivales species should be included in future studies. Several hybridization events between the Argentea and Ivesioid clades may have given rise to the species of Wolf’s grex Rivales. This is the first time that reticulate evolution has been proven in the genus Potentilla, and shows the importance of continuing working with low-copy markers in order to properly resolve its evolutionary history. intermedia are allopolyploids with a shared evolutionary history involving at least four parental lineages, three from the Argentea clade and one from the Ivesioid clade. This is likely due to genomic reorganizations following genome duplication, but the gene trees were not in conflict with a species tree of presumably diploid taxa obtained by Multispecies Coalescent analysis. ![]() Gene trees based on three low-copy nuclear markers, obtained by Bayesian Inference and Maximum Likelihood analyses, showed slightly different topologies. Potentilla species of low ploidy level known to belong to other relevant clades were also included. norvegica and its two subspecies were included, along with the morphologically similar P. ![]() Specimens covering the circumpolar distribution of P. In order to trace the putative allopolyploid origin of the species, sequence data from low-copy, biparentally inherited, nuclear markers were used. norvegica L.) has genetic material from two separate clades within Potentilla the Argentea and the Ivesioid clades – and thus a possible history of hybridization and polyploidization (allopolyploidy). Previous studies based on ribosomal and chloroplast data indicated that Norwegian cinquefoil ( P. Most cinquefoils ( Potentilla L., Rosaceae) are polyploids, ranging from tetraploid (4 x) to dodecaploid (12 x), diploids being a rare exception.
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