Prior to the present study there was limited knowledge about the genetic basis of plant colonization on the 50-year-old island of Surtsey, South Iceland. The aim here was to compare genetic structure of two contrasting species, Festuca rubra (arctic fescue) and Empetrum nigrum (crowberry), which have colonized Surtsey since 1973 and 1993, respectively. Inter-simple sequence repeat (ISSR) markers were used to assess genetic diversity and population structure. Two census periods were compared: 1996-1997 and 2005-2006. Using six ISSR primers, we obtained 103 and 139 discernible DNA fragments from F. rubra and E. nigrum respectively. Although the two species displayed similarly high genetic diversity indices (h = 0.238 and 0.235; I = 0.384 and 0.380, respectively), they differed significantly in their genetic profiles. Festuca was genetically structured at the subpopulation level (FST = 0.034, p = 0.007), whereas Empetrum showed a lack of genetic differentiation. A Bayesian STRUCTURE computation further revealed temporal and spatial genetic structure of the species. The early arrival grass F. rubra has expanded from a local genepool. The population was however initially established from different sources, forming a genetic melting pot on Surtsey. On the other hand, the late arrival shrub E. nigrum probably derived from a common source of immigrants.

The genetic diversity of two Aconitum species endemic to the Carpathian Mountains and Sudetes was studied. A reticulate evolution between them was earlier postulated as an effect of secondary contact. The genetic diversity at the individual and taxonomic levels was examined across the entire geographical ranges of the taxa in 11 populations based on 247 AFLP markers found in 112 individuals in the Sudetes and Western Carpathians. The overall genetic differentiation was greater within the Sudetic A. plicatum (FST = 0.139, P < 0.001) than within the Carpathian A. firmum (FST = 0.062, P < 0.001), presumably due to the long-lasting geographic isolation between the Giant Mts and Praděd (Sudetes) populations of the species. Interestingly, relatively distant and presently isolated populations of A. plicatum and A. f. subsp. maninense share a part of their genomes. It could be an effect of their common evolutionary history, including past and present reticulations. The introgression among infraspecific taxa of Aconitum is common, probably as a result of seed dispersal within a distance of ca. 20 km (Mantel’s r = 0.36, P = 0.01). Aconitum f. subsp. maninense had the highest genetic diversity indices: Nei’s h and rarefied FAr, and divergence index DW (P ≤ 0.05), pointing to its presumably ancient age and long-term isolation.

The number of polyploid plants in angiosperms is estimated at about 30-80%, depending on the study, but hybridization between diploids and tetraploids is not a common phenomenon. In this study, our aim was to determine the extent of hybridization and introgression between Aconitum species in a...

Two Early Jurassic localities, the Mecsek Mts in Hungary and Anina in Romania, are similarly significant and both floras are of autochthonous/paraautochthonous origin. In the Early Jurassic the Hungarian locality was a delta plain; the Romanian locality was an intramontane depression filled predominantly by a braided river system. The floristic composition of the two localities (52 genera, 120 species), although superficially similar (25 common genera), differs at species level (only 9 common species) as well as in the proportions of taxa in major plant groups. These differences can be explained by differences in environmental conditions resulting from palaeogeographic and topographic factors. Based on previous and recent studies, alpha diversity as well as statistically (DCA, PCA) differentiated ecogroups are compared and discussed. For common species, the GLM method was used to classify them to particular environmental response types. Their environmental requirements in both ecosystems are evaluated. Some of the shared species showed different preferences at the localities, explainable by their broad ecological tolerance.

Aconitum lasiocarpum (Carpathian endemic) and A. variegatum (European endemic) occur sympatrically in the\ud Polish Western Carpathians. Here their taxonomic hybrid A. ×pawlowskii occurs. The aim of this study was to\ud determine the relationship between the taxonomic (Linnaean approach) and genetic structure (PCR-ISSR analysis)\ud of the populations and individuals in two allopatric and four sympatric populations. We determined 309\ud individuals (OTUs) to species, subspecies and nothospecies using the Linnaean system of classification, and then\ud genetically fingerprinted 39 randomly chosen OTUs. Comparison of the Nei and Li distances obtained from ISSR\ud and morphological matrices using the Mantel test indicated a significant correlation (n = 39, r = 0.53, P = 0.001).\ud Genetic analysis (NEWHYBRIDS) pointed to 7 OTUs as being later-generation hybrids (B1 introgessants) in the\ud sympatric area. Five of them belong to A. variegatum, indicating cryptic introgression, and two belong to\ud A. ×pawlowskii. Nonmetric multidimensional scaling (NDMS) showed gene flow between A. lasiocarpum and\ud A. ×pawlowskii. Allopatric, morphologically pure A. lasiocarpum and A. variegatum populations differed significantly\ud in their ISSR profiles (Fischer's R×C test, P < 0.0001). Expected heterozygosity (Hj) was significantly\ud (p=0.05) lower in allopatric (0.1261–0.1268) than in sympatric populations (0.1348–0.1509), indicating a genetic\ud melting pot in sympatry. The results support the existence of a natural interspecific hybrid swarm zone in the\ud sympatric area of occurrence of Aconitum, and the taxonomic circumscription of the nothospecies within the\ud Linnaean taxonomic system

The subalpine vegetation in the Eastern Carpathians has been under agropastoral influence as a high-mountain open pasture for about five centuries. Today, the subalpine zone released by human intervention is growing as thickets. In this study, we use a numerical model of tree crowns (CHM, Canopy Height Model) based on laser scanning (LiDAR) and a high-resolution digital terrain model (DTM) to delineate the subalpine thicket distribution. Anselin ‘Local Moran's I’ statistic was used to find hot and cold spots in vegetation cover. We used a logistic generalized linear model (GLM) and Principal Component Analysis (PCA) to set for the historical, climatic and terrain conditions candidates as the predictors of the present-day distribution of vegetation hot spots. We use variance partitioning to assess the interaction of climate and terrain variables. The resulting model suggests key environmental controls that underlie the vegetation pattern. Namely, snow in terrain depressions protects woody vegetation against abrasion and winter drought and increased insolation reduces the site humidity in the summer on S-E exposure hampering re-vegetation. In addition, the increasing distance from the treeline declines the rate of secondary succession. In all, the spatial model predicts the 35% coverage by thickets as a theoretical maximum of available climatic-terrain niches. The results suggest that the growth of the subalpine thicket, in the face of growing global temperature, may be restricted due to the limited number of niches available.