January 13, 2019

Our new paper on the contrasting evolutionary origins of Saxifraga wahlenbergii and S. styriaca has just appeared in BMC Evolutionary Biology.

This study was carried out in a collaboration between our group and Natalia Tkach and Martin Röser (University of Halle-Wittenberg) and Peter Schönswetter (University of Innsbruck). We addressed the evolutionary history of an emblematic yet enigmatic endemic species of the Western Carpathians, Saxifraga wahlenbergii Ball, considered a regional Tertiary palaeoendemic, for which phylogenetic relationships remained obscure. We also included in our analysis a recently described narrow-endemic of the Eastern Alps, S. styriaca Köckinger, suggested to be a previously unknown closest relative of the Carpathian taxon.

Based on nuclear and plastid phylogenies, further supported by ITS genomic screening using high-throughput sequencing, we demonstrated a complicated hybrid origin of S. wahlenbergii. It involved the maternal parent belonging to a Western Eurasian lineage of high mountain taxa grouped in subsect. Androsaceae (most likely the widespread S. androsacea) and the second parent belonging to the distantly related subsect. Tridactylites (S. adscendens?). In turn, S. styriaca, unambiguously assigned to subsect. Androsaceae, was not confirmed as the sister taxon of S. wahlenbergii. Molecular dating indicated the origin of the younger paternal, S. adscendens-like, ITS DNA found in S. wahlenbergii to ca. 4.7 Ma., and the hybrid origin of the Carpathian endemic most likely took place in the Pleistocene. Intraspecific variation observed in cpDNA may indicate an age preceding at least the last glaciation.

Citation

Tkach N, Röser M, Suchan T, Cieślak E, Schönswetter P, Ronikier M, 2019. Contrasting evolutionary origins of two mountain endemics: Saxifraga wahlenbergii (Western Carpathians) and S. styriaca (Eastern Alps). BMC Evolutionary Biology 19:18. DOI