Aconitum lasiocarpum (Carpathian endemic) and A. variegatum (European endemic) occur sympatrically in the Polish Western Carpathians. Here their taxonomic hybrid A. ×pawlowskii occurs. The aim of this study was to determine the relationship between the taxonomic (Linnaean approach) and genetic structure (PCR-ISSR analysis) of the populations and individuals in two allopatric and four sympatric populations. We determined 309 individuals (OTUs) to species, subspecies and nothospecies using the Linnaean system of classification, and then genetically fingerprinted 39 randomly chosen OTUs. Comparison of the Nei and Li distances obtained from ISSR and morphological matrices using the Mantel test indicated a significant correlation (n = 39, r = 0.53, P = 0.001). Genetic analysis (NEWHYBRIDS) pointed to 7 OTUs as being later-generation hybrids (B1 introgessants) in the sympatric area. Five of them belong to A. variegatum, indicating cryptic introgression, and two belong to A. ×pawlowskii. Nonmetric multidimensional scaling (NDMS) showed gene flow between A. lasiocarpum and A. ×pawlowskii. Allopatric, morphologically pure A. lasiocarpum and A. variegatum populations differed significantly in their ISSR profiles (Fischer's R×C test, P < 0.0001). Expected heterozygosity (Hj) was significantly (p=0.05) lower in allopatric (0.1261-0.1268) than in sympatric populations (0.1348-0.1509), indicating a genetic melting pot in sympatry. The results support the existence of a natural interspecific hybrid swarm zone in the sympatric area of occurrence of Aconitum, and the taxonomic circumscription of the nothospecies within the Linnaean taxonomic system
We studied the thermophilous grass Bromus erectus in Central Europe to determine its pattern of population genetic structure and genetic diversity, using ISSR-PCR fingerprinting to analyze 200 individuals from 37 populations. We found three genetic groups with a clear geographic structure, based on a Bayesian approach. The first group occurred west and south of the Alps, the second east and north of the Alps, and the third was formed by four genetically depauperated populations in Germany. The populations from Germany formed a subset of the Bohemian-Moravian populations, with one private allele. Two differentiation centers, one in the Atlantic- Mediterranean and the second in the Pannonian-Balkan area, were recognized by species distribution modeling. The geographic distribution of the genetic groups coincides with the syntaxonomic split of the Festuco-Brometea class into the Festucetalia valesiaceae and Brometalia erecti orders. We found a statistically significant decrease in mean ISSR bands per individual from south to north, and to a lesser extent from the east to west. The former was explained by Holocene long-distance migrations from southern refugia, the latter by the difference in the gradient of anthropopression. We hypothesize a cryptic northern shelter of the species in Central Europe in the putative Moravian-Bohemian refugium.