Teucrium, with an almost cosmopolitan distribution, comprises about 250 species and is the second ‐ largest genus of subfamily Ajugoideae (Lamiaceae). Phylogenetic studies were conducted using nuclear ribosomal DNA (ITS) and chloroplast (ndhF gene, trnL‐F region) DNA sequence data from 101 taxa to estimate phylogenetic relationships among Teucrium and its closest allies. We conclude that: (1) Teucridium, Spartothamnella and Oncinocalyx are nested within Teucrium, thus rendering the latter paraphyletic; (2) previously proposed taxonomic classification systems for Teucrium mostly are not supported by our phylogenetic results; (3) Rubiteucris and Schnabelia appear to be sister to Teucrium. Our results indicate that, among various morphological characters, the calyx shape is diagnostic for different clades within Teucrium. Based on the cladograms derived in this study, the pattern of karyotype evolution suggests that switches in ploidy level are common in at least two groups. Adaptations to drought stress and the regional establishment of Mediterranean climates obviously facilitated speciation and the spread of the genus. Molecular dating analyses indicate diversification of Teucrium at the middle/late Miocene boundary, correlated with Tertiary climatic and tectonic changes.
The shrubby milkwort (Polygala chamaebuxus L.) is widely distributed in the Alps, but occurs also in the lower mountain ranges of Central Europe such as the Franconian Jura or the Bohemian uplands. Populations in these regions may either originate from glacial survival or from postglacial recolonization. In this study, we analyzed 30 populations of P. chamaebuxus from the whole distribution range using AFLP (Amplified Fragment Length Polymorphism) analysis to identify glacial refugia and to illuminate the origin of P. chamaebuxus in the lower mountain ranges of Central Europe. Genetic variation and the number of rare fragments within populations were highest in populations from the central part of the distribution range, especially in the Southern Alps (from the Tessin Alps and the Prealps of Lugano to the Triglav Massiv) and in the middle part of the northern Alps. These regions may have served, in accordance with previous studies, as long‐term refugia for the glacial survival of the species. The geographic pattern of genetic variation, as revealed by analysis of molecular variance, Bayesian cluster analysis and a PopGraph genetic network was, however, only weak. Instead of postglacial recolonization from only few long‐term refugia, which would have resulted in deeper genetic splits within the data set, broad waves of postglacial expansion from several short‐term isolated populations in the center to the actual periphery of the distribution range seem to be the scenario explaining the observed pattern of genetic variation most likely. The populations from the lower mountain ranges in Central Europe were more closely related to the populations from the southwestern and northern than from the nearby eastern Alps. Although glacial survival in the Bohemian uplands cannot fully be excluded, P. chamaebuxus seems to have immigrated postglacially from the southwestern or central‐northern parts of the Alps into these regions during the expansion of the pine forests in the early Holocene.
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