Diversification of the European species of bladdernuts (Staphylea, Staphyleaceae) in the context of the whole genus and the rich fossil record

Abstract

Staphyleaceae is a small family of shrubs and trees with its name-giving genus Staphylea having a highly disjunct distribution. Staphylea has a rich fossil record and was an important element in warm temperate Tertiary forests and is therefore regarded as a Tertiary relic. Based on DNA-sequence analyses of the nuclear marker ITS 1–2 and the chloroplast marker trnL-F as well as AFLP fingerprinting (amplified fragment length polymorphisms) we have gained more insights into the evolution and diversification of the two “European” bladdernut species, the widespread diploid Staphylea pinnata and the tetraploid S. colchica of the Caucasus. As the Caucasus is located west of the Ural Mountains, we consider both species as European. Staphylea pinnata seems to be involved in the hybridization of the likely allo-poly-ploidization of S. colchica together with an unknown, supposedly now extinct species. Ancient repeat types of ITS 1–2 in S. pinnata of Central Europe and Georgia suggested possible glacial refugia in Georgia, sequence similarity (especially a characteristic gap) in ITS 1–2 sequences of Ukrainian and Central European samples indicate refugia also in Ukraine, in the Dniester-Prut interfluve and the Bukovina Precarpathian region, as assumed by Derevenko (2005). Staphylea emodi from the Tibetan Plateau, the Staphylea species closest to the European ones was more closely related to the European species than to American species in our research.