Molecular Phylogeny and Phylogeography of Potentilla multifida L. agg. (Rosaceae) in Northern Eurasia with Special Focus on Two Rare and Critically Endangered Endemic Species, P. volgarica and P. eversmanniana

The results of a molecular genetic study of <i>Potentilla multifida</i> agg. using two plastid markers (<i>ndhC-trnV</i> and <i>psbA-trnH</i>) and a nuclear ITS marker suggested that this group comprises a number of relatively young and incompletely differentiated species widely distributed in Northern Eurasia. The sequences were analyzed using tree-based (maximum likelihood) and network-based (statistical parsimony network) approaches. The plastid data suggested incomplete lineage sorting, characteristic of the group as a whole. The nuclear ITS results demonstrated quite a different pattern, with mostly conspecific accessions shaping monophyletic clades. The majority of the <i>Potentilla</i> sect. <i>Multifidae</i> species studied possess few, usually closely related plastid haplotypes, or are even monomorphic. In contrast, <i>P. volgarica</i>, a narrow endemic from the Volga River valley, presents plastid haplotypes belonging to two distantly related groups. Such a pattern of genetic diversity in <i>P. volgarica</i> may be explained by a long persistence of the species within an extremely small distribution range, on the right bank of the Volga River, most likely representing a contemporary refugium. The genealogy of plastid markers in <i>P. volgarica</i> suggests that this species is ancestral to <i>P.</i><i>eversmanniana,</i> another narrow endemic from the S Urals.