BACKGROUND AND AIMS:Several evolutionary drivers have been proposed to explain the exceptional species and genetic diversity of the Balkan flora, including the moderate impact of glaciations enabling long-term in situ persistence, ecological and topographic heterogeneity promoting vicariant differentiation, and polyploidy. Despite these shared drivers, plant lineages often show contrasting evolutionary histories, suggesting lineage-specific rather than broadly generalizable responses. The genus Erysimum, notable for its high endemism, karyological variation, recent and rapid speciation, and signatures of reticulate evolution, provides an excellent model for exploring this diversity of evolutionary trajectories and speciation drivers in the Balkans. METHODS:Focusing on five Balkan endemics of the E. odoratum species complex sampled from 47 populations, we examined chromosomal and genome size variation and applied two complementary genomic approaches, target enrichment (Hyb-Seq) and RADseq, along with morphometric analyses. These datasets were used to circumscribe species, uncover intraspecific variation patterns, and assess the extent and evolutionary consequences of interspecific gene flow and polyploidy. KEY RESULTS:Genetic and morphological evidence was largely congruent, clarifying species boundaries but also revealing cryptic diversity, leading to the recognition of eight entities. Most diversity was concentrated in the southern Dinarides, where we detected multiple cytotypes, an undescribed lineage, a polyphyletic species resulting from two independent autopolyploidization events, and allotetraploids arising in a contact zone. Geographic distance and biogeographic barriers across the mountainous Balkan landscape likely shaped patterns of divergence and promoted speciation. Discrepancies between chromosome numbers and genome size indicate dynamic chromosomal evolution. CONCLUSIONS:Vicariant differentiation, auto- and allopolyploidy, genome size and chromosomal dynamics together account for the pronounced diversity of Erysimum in the Balkans, illustrating how speciation is driven within this biodiversity hotspot. Importantly, substantial evolutionary potential is retained within species, as the coexistence of multiple intraspecific genetic lineages and cytotypes can reinforce reproductive barriers and promote future diversification.

Novel invasive genotypes can arise through polyploidisation, hybridisation, or gene flow between populations of distinct origins or related species. Solidago gigantea, a notorious European invader, has long been reported exclusively as tetraploid in its invasive range. Recently, mixed-ploidy populations, including tetraploid and pentaploid plants, were discovered; yet the potential role of the novel pentaploid cytotype (and its progeny) in S. gigantea invasions remains poorly understood. This study aims to elucidate the origin of pentaploids and the cytotype and genetic structure of mixed-ploidy populations, characterise the reproductive mode and mating interactions of pentaploid plants, and assess their fitness and potential contribution to invasiveness using relative DNA content screening, ddRADseq population genetics, and reproductive potential and fitness assessments. Molecular analyses revealed that pentaploids constitute a genetically distinct lineage within S. gigantea. Our results rule out both an autopolyploid origin from the common tetraploid cytotype and an allopolyploid origin via hybridisation with co-occurring native or invasive Solidago species. The pentaploid cytotype reproduces exclusively through clonal propagation; its low genetic variability suggests that the two studied populations may belong to a single extensive clonal genet. Pentaploids produce viable gametes but appear to exhibit strict self-incompatibility, preventing the formation of offspring within the same genotype. However, pentaploid S. gigantea engages in bidirectional mating with co-occurring tetraploid plants, yielding well-developed seeds with offspring ploidy ranging from 4x to 5x (predominantly aneuploid). Despite this cytological variability, progeny from mixed-ploidy populations displayed germination rates and early growth comparable to those from pure tetraploid populations. Notably, at least some tetraploid offspring from 4x–5x crosses successfully established, flowered, and backcrossed with pentaploid plants to produce viable seeds of subsequent introgressed generations. The pentaploid cytotype of S. gigantea introduces a new post-invasion dynamic to its invasive populations. Rather than being an evolutionary dead-end, this cytotype may potentially enhance the species’ invasiveness through three evolutionary pathways: (1) a highly successful clonal life strategy enabling both local and long-distance spread; (2) genetic enrichment of tetraploid populations via ongoing interploidy crosses; and (3) establishment of novel aneuploid genotypes due to the remarkable tolerance of chromosomal instability observed in S. gigantea.

Two perennial goldenrods, Solidago canadensis and S. gigantea (Asteraceae), are considered successful plant invaders with an exceptional ability to affect the biodiversity and environment of native ecosystems in Europe. However, their species-specific invasion impacts and associated ecological mechanisms shaping the species diversity of plant guilds and the soil conditions in grasslands remain poorly understood. Here, a spatial invasion-gradient approach with different invasion levels categorised by the percentage of goldenrod cover (heavily invaded > 50%, transitional invaded 20–50% and uninvaded control plots) was used to assess invasion impacts on species diversity of forbs, graminoids and bryophytes as well as on soil and vegetation properties in semi-natural grasslands of Slovakia (Central Europe). Multi-guild diversity assessment showed that graminoids were more tolerant than forbs of the competitive and stressful conditions in invaded plots. Invasion level reduced species richness of forbs in heavily invaded plots, likely owing to intensified competition and litter accumulation generated by dense Solidago stands. No invasion effect was found on graminoid and bryophyte species diversity metrics. Most variation in species diversity and ecological responses was addressed to the shared invasion impacts of both Solidago species, but several species-specific invasion effects on forb diversity indices and soil chemistry (soil reaction, nitrogen and potassium concentrations, C-to-N ratio) were also identified. The contrasting forb responses in Shannon and Simpson diversity indices corresponded to shifts in community evenness associated with species-specific effects of the invaders on soil nutrient cycling and productivity. Goldenrod invasions also altered community structure, primarily through shifts in abundance-dominance interactions rather than through substantial species replacement. Our results highlight the importance of recording invasion impacts across functional guilds and ecosystem components to better understand the mechanisms of plant invasion in semi-natural grasslands.

Hybrid zones provide excellent opportunities to study evolutionary processes linked to interspecific gene flow, including introgression, genetic erosion, polyploid establishment, and speciation. The genus Cardamine (Brassicaceae) serves as an excellent model for polyploid evolution, including one of the few well-documented neo-allopolyploid species that have evolved in the last 300 yr. Using a combination of flow cytometric screening of nuclear DNA content, next-generation restriction site-associated DNA sequencing, and genomic in situ hybridization, we uncovered an unprecedented case of extensive interspecific hybridization in Cardamine, involving four parental species and their predominantly triploid offspring. We demonstrate the recurrent and polytopic origins of both autotriploids and allotriploids, the latter integrating different parental genomes. Our findings highlight Cardamine rivularis as a central player in this system, likely producing unreduced female gametes at a high rate, which drives the formation of diverse triploids. However, this species may also face the risk of genetic swamping and ecological displacement. The substantial genetic variation of the hybrids, their high frequency, partial fertility, and efficient clonal spread suggest significant evolutionary potential. Overall, we propose that these hybrid zones provide a rare and valuable natural laboratory for studying the emergence of neo-allopolyploids and the mechanisms shaping polyploid evolution.

KMa , https://orcid.org/0000-0002-7658-0844 ; JK , https://orcid.org/0000-0002-9983-7630 ; RGA , https://orcid.org/0009-0000-0176-7252 ; JČ , https://orcid.org/0000-0002-2370-2051 ; AHE , https://orcid.org/0000-0002-7930-5696 ; SVG , https://orcid.org/0000-0002-7678-9648 ; AGG , https://orcid.org/0000-0002-4580-2061 ; AVH , https://orcid.org/0009-0009-4791-3919 ; IH , https://orcid.org/0000-0002-9905-381X ; ZHH , https://orcid.org/0000-0001-8880-2144 ; IJ , https://orcid.org/0000-0003-2105-5310 ; TK , –; EK , https://orcid.org/0000-0001-9641-5750 ; FK , https://orcid.org/0000-0002-8793-7992 ; CL , https://orcid.org/0000-0002-2450-5455 ; TM , https://orcid.org/0000-0001-6485-0563 ; KMa , https://orcid.org/0000-0002-7658-0844 ; LYuM , https://orcid.org/0000-0001-9385-6462 ; LM , https://orcid.org/0000-0003-4478-5930 ; LAM , https://orcid.org/0000-0002-1283-3865 ; KMu , https://orcid.org/0000-0003-1585-6226 ; YMN , https://orcid.org/0000-0003-4749-0839 ; AAN , https://orcid.org/0000-0002-4380-7715 ; MN , https://orcid.org/0000-0002-1594-2418 ; AP , https://orcid.org/0000-0003-3620-6695 ; AVP , https://orcid.org/0009-0004-3522-5936 ; PP , https://orcid.org/0000-0001-8500-442X ; BŠ , https://orcid.org/0000-0002-6487-6373 ; KS , https://orcid.org/0000-0002-1452-5428 ; MŠ , https://orcid.org/0000-0002-5919-890X ; SŠ , https://orcid.org/0000-0003-4809-4379 ; GŠ , https://orcid.org/0000-0002-7439-2911 ; EZ , https://orcid.org/0000-0003-2992-2941 ; JZ-L , https://orcid.org/0000-0002-8950-6643

Accurate species delimitation is essential for understanding biodiversity and evolutionary processes, yet it remains challenging in taxonomically complex groups shaped by recent divergence and reticulate evolution. Nevertheless, such groups offer unique insights into the earliest stages of speciation and its driving forces. The genus Erysimum (Brassicaceae), notable for its karyological diversity and high endemism, represents an excellent model for such studies. Here, we investigated the E. odoratum complex, encompassing up to 10 recognized species in the Carpathians and western Balkans, to test its monophyletic origin, clarify species boundaries and elucidate the main drivers of diversification. We combined cytotype screening (chromosome counting and flow cytometry), morphometric analysis, and two high-throughput sequencing methods: RADseq, to resolve phylogenetic relationships as well as to detect fine-scale genetic structure and introgression; and target enrichment (Hyb-Seq), to elucidate polyploid origins. Our results demonstrate that the studied complex is polyphyletic, and we focused on the lineage comprising E. odoratum s.str. and Carpathian species. Phylogenomic data from the Carpathians contradict traditional taxonomy, which recognized up to four diploid endemics, and instead support a single species, E. witmannii with geographically structured genetic variation. Within E. odoratum s.str., we identified multiple polyploid cytotypes resulting from independent auto- and allopolyploidization events, although disentangling parental subgenomes, ancestral polymorphisms, and introgression remains difficult. We propose that diversification in this species complex has been driven by a combination of allopatric divergence and reticulate evolution (involving both introgression and allopolyploidy), further shaped by chromosomal dynamics such as dysploidy.

River corridors are among the most important natural pathways for invasive species to spread into landscapes. Nevertheless, the ecological processes underlying invasions of riparian habitats are poorly understood for many taxonomic groups. We sampled bryophytes, vascular plants, and molluscs along three West Carpathian rivers (Central Europe) to identify spatial trends and drivers of native and alien species diversity across multiple taxa. Generalised additive models revealed decreasing downstream diversity patterns across all studied rivers and taxonomic groups. In contrast, alien diversity showed the opposite trend, displaying a high degree of idiosyncrasy among the rivers. Random forest analysis revealed that climate-induced variables (altitude and related temperature) played a more pronounced role in the diversity of alien species than in the diversity of native species. The diversity of native species was more influenced by local land use and habitat alternations (molluscs) or by source-to-mouth river interactions along the longitudinal gradient (plants). Dispersal limitation and temperature constrain alien species distributions along river corridors, while a multitude of natural and anthropic influences drive native species diversity. The climate-driven distribution of alien plants and molluscs suggests future altitudinal and longitudinal shifts in non-native species along river corridors, which will be exacerbated by ongoing climate warming and associated environmental changes.

Background and Aims Invasive species are a threat to the conservation of biological systems. In Central Europe, riparian ecosystems are especially susceptible to plant invasions, as waterflow mediates the spread of plant propagules, while invasive species may then affect soil including soil microbial communities. As waterflow also enhances connectivity among different segments of a river, spatial continuity of abiotic as well as biotic components of riparian ecosystems is expected. Methods We studied activity and functional diversity of microbial communities in three headwater streams in Central Europe. Plant diversity, soil properties and soil microbiota were assessed on 20 sample plots per river regularly distributed along the streams. Soil microbial activity and community-level physiological profiling were used to study the soil microbial community. Results Although the α-diversity of plants and soil microbiota was comparable, plant communities were substantially more differentiated than microbial communities. Richness in alien and invasive plants significantly differed among rivers, which was reflected in different spatial patterns and trends of microbial activity and diversity. A high level of spatial continuity and clearest longitudinal trends were observed in the Kysuca river with straightened riverbed and a high occurrence of artificial surfaces in the adjacent areas. The number of both alien and invasive plants significantly affects the composition of microbial functional groups of riverbed soils. Conclusion Continuity of processes in riparian ecosystems was confirmed also for headwater streams. However, the extent to which it applies to a particular stream strongly depends on particular environmental setting and stream characteristics.

Aim: New areas are often simultaneously invaded by closely related alien species; however, between-species differences in the course of their invasive spreading due to diverse ecological preferences have rarely been investigated. Here, we aim to study the species-specific spatio-temporal invasion patterns of Solidago canadensis and S. gigantea.Location: Slovakia-the Western Carpathian and adjacent Pannonian regions.Taxon: Invasive alien Solidago canadensis and S. gigantea.Methods: Our study was based on revised herbarium specimens, a recent field survey which included gathering abundance and habitat data, and environmental data from GIS layers. We characterised the environmental niche differentiation between S. canadensis and S. gigantea. Generalised additive models were then used to identify the key drivers of the species' occurrences and to assess their potential current and future distributions.Results: Both species began to spread in Slovakia in the 1850s; in the first 100 years, the number of S. gigantea sites increased exponentially, while that of S. canadensis remained low. Currently, S. canadensis is more widespread in the region. The species have similar habitat preferences. Their environmental niches overlap, but are not identical. The core distribution of S. canadensis is in foothills and valleys that experience lower annual mean temperatures, while that of S. gigantea is in lowlands with higher annual mean temperatures. A large part of their potential distribution areas seems to be already invaded. Possible future climate change could stimulate the spreading of S. canadensis into higher altitudes and S. gigantea farther into lowlands and Carpathian foothills.Main conclusions: The studied invasive Solidago species differed considerably in the early stages of invasion. Their environmental niches, current realised and potential distribution patterns are different. In the studied region, further spreading, with an increase in the number and size of populations, is likely unless effective measures are undertaken.

Exploring the fitness consequences of whole-genome multiplication (WGM) is essential for understanding the establishment of autopolyploids in diploid parental populations, but suitable model systems are rare. We examined the impact of WGM on reproductive traits in three major cytotypes (2x, 3x, 4x) of Pilosella rhodopea, a species with recurrent formation of neo-autopolyploids in mixed-ploidy populations. We found that diploids had normal female sporogenesis and gametogenesis, high fertility, and produced predominantly euploid seed progeny. By contrast, autopolyploids had highly disturbed developmental programs that resulted in significantly lower seed set and a high frequency of aneuploid progeny. All cytotypes, but particularly triploids, produced gametes of varying ploidy, including unreduced ones, that participated in frequent intercytotype mating. Noteworthy, the reduced investment in sexual reproduction in autopolyploids was compensated by increased production of axillary rosettes and the novel expression of two clonal traits: adventitious rosettes on roots (root-sprouting), and aposporous initial cells in ovules which, however, do not result in functional apomixis. The combination of increased vegetative clonal growth in autopolyploids and frequent intercytotype mating are key mechanisms involved in the formation and maintenance of the largest diploid-autopolyploid primary contact zone ever recorded in angiosperms.

Spatial segregation of cytotypes reduces the negative effect of frequency-dependent mating on the fitness of minority cytotype(s) and thus allows its establishment and coexistence with the majority cytotype in mixed-ploidy populations. Despite its evolutionary importance, the stability of spatial segregation is largely unknown. Furthermore, closely related sympatric cytotypes that differ in their life histories might exhibit contrasting spatial dynamics over time. We studied the temporal stability of spatial structure at a secondary contact zone of co-occurring monocarpic diploids and polycarpic tetraploids of Centaurea stoebe, whose tetraploid cytotype has undergone a rapid range expansion in Europe and became invasive in North America. Eleven years after the initial screening, we re-assessed the microspatial distribution of diploids and tetraploids and their affinities to varying vegetation-cover density in three mixed-ploidy populations in Central Europe. We found that overall, spatial patterns and frequencies of both cytotypes in all sites were very similar over time, with one exception. At one site, in one previously purely 2x patch, diploids completely disappeared due to intensive succession by shrubby vegetation. The remaining spatial patterns, however, showed the same cytotype clumping and higher frequency of 2x despite subtle changes in vegetation-cover densities. In contrast to the expected expansion of polycarpic tetraploids having higher colonization ability when compared to diploids, the tetraploids remained confined to their former microsites and showed no spatial expansion. Spatial patterns of coexisting diploids and tetraploids, which exhibit contrasting life histories, did not change over more than a decade. Such temporal stability is likely caused by relatively stable habitat conditions and very limited seed dispersal. Our results thus imply that in the absence of a disturbance regime connected with frequent human- or animal-mediated seed dispersal, spatial patterns may be very stable over time, thus contributing to the long-term coexistence of cytotypes.

Hybridization between native and alien congeners may pose a serious threat to biodiversity and negatively affect native flora. Here we study Solidago ×niederederi, which originated and became established in Europe as a result of a cross between the alien S. canadensis and native S. virgaurea. The recent increase in the number of records of S. ×niederederi in Europe has highlighted the need to monitor its occurrence, spread and behaviour. In the present study, we tested the effectiveness of flow cytometry for detecting hybrid plants of S. ×niederederi. Sequences of the ITS region of nrDNA and the rpS15-ycf1 spacer of cpDNA were used to confirm the hybrid origin of analysed plants and to identify the maternal species. Our study included 60 single-species populations of S. canadensis, S. gigantea and S. virgaurea, and 16 mixed populations with the presence of hybrid S. ×niederederi sampled from six countries in central Europe and adjacent areas. All individuals of S. canadensis, S. ×niederederi and S. virgaurea investigated were diploid (2n~2x~18) but differed in their relative DNA content values. The DNA content of S. ×niederederi was intermediate between S. canadensis and S. virgaurea with no overlaps, with the differences between the species being statistically significant. Therefore, we conclude that flow cytometry is a reliable and efficient method for detailed screening for hybrids within mixed Solidago populations and for identifying non-flowering or morphologically ambiguous Solidago plants. Since both parental species varied only negligibly in their DNA content, it may also be applicable across a broader geographic scale. Genetic, flow cytometric and distributional data suggest that the hybrids are to a large extent early generation (likely F1) hybrids as very few cases of supposed introgressants were also inferred. The results from chloroplast rpS15-ycf1 spacer showed that hybridization has occurred in both directions.

The paper aims to provide a comprehensive overview of karyological and morphological variability of the Tanacetum corymbosum group in Slovakia. We estimated DNA ploidy level and relative DNA content of 530 individuals (45 populations) using DAPI flow cytometry. The morphological variation was studied by univariate as well as multivariate morphometric based on 10 morphological characters of 351 individuals (39 populations). In addition, two characters were measured on 120 achenes (six populations). Flow cytometry analyses confirmed two predominant cytotypes within T. corymbosum group in Slovakia: diploids corresponding to T. clusii and tetraploids corresponding to T. corymbosum. Further, we recorded rare occurrence (1.3% of the dataset) of minority cytotypes – presumable triploids and pentaploids, probably originating from fusion of reduced and unreduced gamete in single species populations. One triploid plant found at the only one locality with common occurrence of T. clusii and T. corymbosum is most probably of hybrid origin. Morphological analyses showed that T. clusii and T. corymbosum could not be clearly distinguished by either of the studied characters but by combining all studied quantitative characters of stem, leaves, and corymbs, it was possible to correctly classify more than 91% of the plants. Number and size of stem leaves as well as capitula, and coloration of the margin of the involucral bracts were identified as the most useful for their determination. Based on revealed karyological and morphological differentiation of T. clusii and T. corymbosum, we favour to recognize them as two separate species rather than subspecies. A key for identifying native Tanacetum species in Slovakia is presented.

Recurrent polyploid formation and weak reproductive barriers between independent polyploid lineages generate intricate species complexes with high diversity and reticulate evolutionary history. Uncovering the evolutionary processes that formed their present-day cytotypic and genetic structure is a challenging task. We studied the species complex of Cardamine pratensis, composed of diploid endemics in the European Mediterranean and diploid-polyploid lineages more widely distributed across Europe, focusing on the poorly understood variation in Central Europe. To elucidate the evolution of Central European populations we analyzed ploidy level and genome size variation, genetic patterns inferred from microsatellite markers and target enrichment of low-copy nuclear genes (Hyb-Seq), and environmental niche differentiation. We observed almost continuous variation in chromosome numbers and genome size in C. pratensis s.str., which is caused by the co-occurrence of euploid and dysploid cytotypes, along with aneuploids, and is likely accompanied by inter-cytotype mating. We inferred that the polyploid cytotypes of C. pratensis s.str. are both of single and multiple, spatially and temporally recurrent origins. The tetraploid Cardamine majovskyi evolved at least twice in different regions by autopolyploidy from diploid Cardamine matthioli. The extensive genome size and genetic variation of Cardamine rivularis reflects differentiation induced by the geographic isolation of disjunct populations, establishment of triploids of different origins, and hybridization with sympatric C. matthioli. Geographically structured genetic lineages identified in the species under study, which are also ecologically divergent, are interpreted as descendants from different source populations in multiple glacial refugia. The postglacial range expansion was accompanied by substantial genetic admixture between the lineages of C. pratensis s.str., which is reflected by diffuse borders in their contact zones. In conclusion, we identified an interplay of diverse processes that have driven the evolution of the species studied, including allopatric and ecological divergence, hybridization, multiple polyploid origins, and genetic reshuffling caused by Pleistocene climate-induced range dynamics.

Solidago ×niederederi Khek (1905: 22) is a hybrid between North-American S. canadensis Linnaeus (1753: 878) and European native S. virgaurea Linnaeus (1753: 880). Solidago canadensis was introduced to Europe in the 17th century (Kowarik 2003). It has spread invasively throughout Europe since the second half of the 19th century (Weber 1998), reaching, besides sites disturbed by human activity, also (semi)natural biotopes, as forest edges, abandoned meadows and field margins which are often inhabited by native S. virgaurea. Their hybrid was discovered for the first time in nature by a local schoolmaster Franz Niedereder in the area of Vorderstoder village (Austria). Niedereder sent a plant material of the assumed hybrid to Eugen Johan Khek (born in 1861, Neuhaus/Jindřichov Hradec; died in 1927, Vienna), the pharmacist and botanist who lived in Vienna since 1889 (Anonymous 1916). Khek described the hybrid species under the name S. ×niederederi in honour of his discoverer (Khek 1905). The protologue indicates that the relevant communication between Niedereder and Khek was going on between July 1900 (when they met for the first time) and February 1905 (when the hybrid’s description was published). Before its description, Khek studied the hybrid for four years and he saw a herbarium material from Niedereder as well as a living material. In the protologue, no particular herbarium specimens or illustrations had been indicated or associated with S. ×niederederi (Khek 1905).

Besides the well-known negative effects of invasive plant species on autochthonous plant communities, the breakdown of genetic integrity of indigenous species via alien-to-native hybridisation represents an additional direct threat to native flora which should not be underestimated. Our aim was to survey the current distribution of Solidago xniederederi, a hybrid that has originated through spontaneous hybridisation between the native European S. virgaurea and allochthonous (North American) S. canadensis. Although this hybrid was first recorded at the very end of the 19th century, most occurrences have been reported during the last decades. It is only known to grow in Europe and its current distribution is still not well explored. Based on field research in the Carpathians, we list five new localities of S. xniederederi, which represent the first records of this hybrid in Slovakia, Hungary, and Romania. The present paper documents existing reports from 409 sites in 17 European countries. We provide a detailed list of all records from the literature, freely available databases and webpages as well as a summary map of S. xniederederi's known distribution. In addition, records are analysed regarding a time context and habitat preferences. Finally, we discuss a potential threat that the hybrid could pose to the genetic integrity of the native European populations of the Solidago virgaurea complex.

Populations of sympatric diploid and autopolyploid cytotypes provide a unique opportunity to study early stages of polyploid evolution. Pilosella rhodopea is a diploid–autopolyploid complex forming frequent mixed-ploidy populations, most probably representing the largest primary contact zone documented so far in angiosperms. Our aims were to elucidate: (1) the origin of autopolyploids (single vs. multiple); (2) cytotype distribution patterns at various spatial scales; and (3) potential ecological differentiation of the cytotypes by measuring several habitat variables along two elevational transects. In total, five cytotypes were found across the species range. Triploids were the most frequent (50%), followed by diploids (29%) and tetraploids (15%), whereas pentaploids and hexaploids were rare. Most populations were mixed-ploidy. Both amplified fragment length polymorphism and cytotype distribution patterns suggested multiple origins of autopolyploids and frequent intercytotype gene flow. Cytotype diversity and spatial aggregation of the cytotypes were scale dependent. At a local scale (5 m × 5 m), cytotype co-occurrence was frequent, whereas micro-scale plots (1 m × 1 m) were cytotypically more homogeneous. We did not find any evidence for ecological differentiation of the cytotypes. Our results show that P. rhodopea is a rare example of a diploid–autopolyploid complex with polytopic and ongoing polyploid formations in primary contact zones. Recurrent formation of polyploids owing to a frequent intercytotype gene flow among spatially close cytotypes might explain, at least in part, the sympatric coexistence of cytotypes.

The proportion of endemic taxa is a frequently used measure for assesment of biodiversity hotspots within the Carpathians. For confirming of an endemic status of a taxon, a thorough evaluation using modern tools of plant systematics is desirable. Tephroseris longifolia subsp. moravica has been considered to be a Western Carpathian endemic, but a previous study of morphological and genome size differentiation within the T. longifolia agg. showed that its endemic position is controversial. Therefore, in this study we aimed to detect genetic variability and evolutionary relationships within the T. longifolia agg. using nuclear ITS sequences and highly variable AFLPs on 38 populations covering the distribution range of the aggregate. Additionally, we analysed 22 populations of other putatively related species (T. aurantiaca, T. capitata, T. crispa, T. integrifolia and T. papposa). Genetic analyses proved that T. longifolia agg. is genetically well differentiated, but the results contradict the current taxonomic concept. Tephroseris longifolia aggregate, as defined here, comprises T. longifolia, T. crispa, T. pseudocrispa, T. tenuifolia and T. italica. Within T. longifolia, two subspecies can be recognised, namely T. l. subsp. longifolia and T. l. subsp. moravica. Furthermore, AFLPs confirm the close relationship of Pannonian and one Croatian populations to T. l. subsp. moravica. Therefore, we assume that T. l. subsp. moravica should not be considered a Western Carpathian endemic and most probably migrated to the Western Carpathian area during the post-glacial period.