BACKGROUND: Whole-genome duplication (polyploidization) is a dominant force in sympatric speciation, particularly in plants. Genome doubling instantly poses a barrier to gene flow owing to the strong crossing incompatibilities between individuals differing in ploidy. The strength of the barrier, however, varies from species to species and recent genetic investigations revealed cases of rampant interploidy introgression in multiple ploidy-variable species. SCOPE: Here, we review novel insights into the frequency of interploidy gene flow in natural systems and summarize the underlying mechanisms promoting interploidy gene flow. Field surveys, occasionally complemented by crossing experiments, suggest frequent opportunities for interploidy gene flow, particularly in the direction from diploid to tetraploid, and between (higher) polyploids. However, a scarcity of accompanying population genetic evidence and a virtual lack of integration of these approaches leave the underlying mechanisms and levels of realized interploidy gene flow in nature largely unknown. Finally, we discuss potential consequences of interploidy genome permeability on polyploid speciation and adaptation and highlight novel avenues that have just recently been opened by the very first genomic studies of ploidy-variable species. Standing in stark contrast with rapidly accumulating evidence for evolutionary importance of homoploid introgression, similar cases in ploidy-variable systems are yet to be documented. CONCLUSIONS: The genomics era provides novel opportunity to re-evaluate the role of interploidy introgression in speciation and adaptation. To achieve this goal, interdisciplinary studies bordering ecology and population genetics and genomics are needed.

• Klíčová slova
• Adaptation, evolution, genetic introgression, polyploidy, speciation, whole-genome duplication,
• MeSH
• biologická evoluce MeSH
• genom rostlinný genetika   MeSH
• ploidie MeSH
• polyploidie * MeSH
• rostliny genetika   MeSH
• rozmnožování genetika   MeSH
• tok genů * MeSH
• vznik druhů (genetika) MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

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.

• Klíčová slova
• Centaurea stoebe, colonization, cytotype coexistence, disturbance, flow cytometry, invasion, mixed-ploidy population, polycarpy, polyploidy, secondary contact zone, spatial cytotype structure, spatial segregation,
• Publikační typ
• časopisecké články MeSH

The contents of photosynthetic pigments are an important indicator of many processes taking place in the plant body. Still, however, our knowledge of the effects of polyploidization, a major driver of speciation in vascular plants, on the contents of photosynthetic pigments is very sparse. We compared the contents of photosynthetic pigments among natural diploids, natural tetraploids, and synthetic tetraploids. The material originated from four natural mixed-cytotype populations of diploid and autotetraploid Vicia cracca (Fabaceae) occurring in the contact zone between the cytotypes in Central Europe and was cultivated under uniform conditions. We explored whether the contents of pigments are primarily driven by polyploidization or by subsequent evolution of the polyploid lineage and whether the patterns differ between populations. We also explored the relationship between pigment contents and plant performance. We found very few significant effects of the cytotype on the individual pigments but many significant interactions between the cytotype and the population. In pair-wise comparisons, many comparisons were not significant. The prevailing pattern among the significant once was that the contents of pigments were determined by polyploidization rather than by subsequent evolution of the polyploid lineage. The contents of the pigments turned out to be a useful predictor of plant performance not only at the time of material collection, but also at the end of the growing season. Further studies exploring differences in the contents of photosynthetic pigments in different cytotypes using replicated populations and assessing their relationship to plant performance are needed to assess the generality of our findings.

• Klíčová slova
• Carotenoids, Colchicine, Legume, Photoprotective pigments, Plant performance, Synthetic polyploids,
• MeSH
• biologické pigmenty genetika   metabolismus   MeSH
• diploidie MeSH
• fotosyntéza genetika   MeSH
• polyploidie MeSH
• tetraploidie MeSH
• vikev genetika   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• biologické pigmenty MeSH

BACKGROUND AND AIMS: The origin of different cytotypes by autopolyploidy may be an important mechanism in plant diversification. Although cryptic autopolyploids probably comprise the largest fraction of overlooked plant diversity, our knowledge of their origin and evolution is still rather limited. Here we study the presumed autopolyploid aggregate of Aster amellus, which encompasses diploid and hexaploid cytotypes. Although the cytotypes of A. amellus are not morphologically distinguishable, previous studies showed spatial segregation and limited gene flow between them, which could result in different evolutionary trajectories for each cytotype. METHODS: We combine macroevolutionary, microevolutionary and niche modelling tools to disentangle the origin and the demographic history of the cytotypes, using chloroplast and nuclear markers in a dense population sampling in central Europe. KEY RESULTS: Our results revealed a segregation between diploid and hexaploid cytotypes in the nuclear genome, where each cytotype represents a monophyletic lineage probably homogenized by concerted evolution. In contrast, the chloroplast genome showed intermixed connections between the cytotypes, which may correspond to shared ancestral relationships. Phylogeny, demographic analyses and ecological niche modelling supported an ongoing differentiation of the cytotypes, where the hexaploid cytotype is experiencing a demographic expansion and niche differentiation with respect to its diploid relative. CONCLUSIONS: The two cytotypes may be considered as two different lineages at the onset of their evolutionary diversification. Polyploidization led to the occurrence of hexaploids, which expanded and changed their ecological niche.

• MeSH
• Aster genetika   MeSH
• biologická evoluce * MeSH
• biologické modely MeSH
• DNA chloroplastová analýza   MeSH
• fylogeneze * MeSH
• fylogeografie MeSH
• genetické markery MeSH
• mezerníky ribozomální DNA analýza   MeSH
• polyploidie * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• Názvy látek
• DNA chloroplastová MeSH
• genetické markery MeSH
• mezerníky ribozomální DNA MeSH

BACKGROUND AND AIMS: Despite the recent wealth of studies targeted at contact zones of cytotypes in various species, some aspects of polyploid evolution are still poorly understood. This is especially the case for the frequency and success rate of spontaneous neopolyploidization or the temporal dynamics of ploidy coexistence, requiring massive ploidy screening and repeated observations, respectively. To fill this gap, an extensive study of spatio-temporal patterns of ploidy coexistence was initiated in the widespread annual weed Tripleurospermum inodorum (Asteraceae). METHODS: DNA flow cytometry along with confirmatory chromosome counts was employed to assess ploidy levels of 11 018 adult individuals and 1263 ex situ germinated seedlings from 1209 Central European populations. The ploidy screening was conducted across three spatial scales and supplemented with observations of temporal development of 37 mixed-ploidy populations. KEY RESULTS: The contact zone between the diploid and tetraploid cytotypes has a diffuse, mosaic-like structure enabling common cytotype coexistence from the within-population to the landscape level. A marked difference in monoploid genome size between the two cytotypes enabled the easy distinction of neotetraploid mutants from long-established tetraploids. Neotetraploids were extremely rare (0·03 %) and occurred solitarily. Altogether five ploidy levels (2 x -6 x ) and several aneuploids were discovered; the diversity in nuclear DNA content was highest in early ontogenetic stages (seedlings) and among individuals from mixed-ploidy populations. In spite of profound temporal oscillations in cytotype frequencies in mixed-ploidy populations, both diploids and tetraploids usually persisted up to the last census. CONCLUSIONS: Diploids and tetraploids commonly coexist at all spatial scales and exhibit considerable temporal stability in local ploidy mixtures. Mixed-ploidy populations containing fertile triploid hybrids probaby act as effective generators of cytogenetic novelty and may facilitate inter-ploidy gene flow. Neopolyploid mutants were incapable of local establishment.

• Klíčová slova
• Matricaria perforata, Tripleurospermum inodorum, aneuploidy, annual plant, cytotype coexistence, flow cytometry, mixed-ploidy population, neopolyploid, ploidy screening, temporal dynamics, triploid,
• MeSH
• Asteraceae genetika   MeSH
• biologická evoluce * MeSH
• diploidie MeSH
• polyploidie * MeSH
• tetraploidie MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Evropa MeSH

BACKGROUND AND AIMS: Understanding the direct consequences of polyploidization is necessary for assessing the evolutionary significance of this mode of speciation. Previous studies have not studied the degree of between-population variation that occurs due to these effects. Although it is assumed that the effects of the substances that create synthetic polyploids disappear in second-generation synthetic polyploids, this has not been tested. METHODS: The direct consequences of polyploidization were assessed and separated from the effects of subsequent evolution in Vicia cracca , a naturally occurring species with diploid and autotetraploid cytotypes. Synthetic tetraploids were created from diploids of four mixed-ploidy populations. Performance of natural diploids and tetraploids was compared with that of synthetic tetraploids. Diploid offspring of the synthetic tetraploid mothers were also included in the comparison. In this way, the effects of colchicine application in the maternal generation on offspring performance could be compared independently of the effects of polyploidization. KEY RESULTS: The sizes of seeds and stomata were primarily affected by cytotype, while plant performance differed between natural and synthetic polyploids. Most performance traits were also determined by colchicine application to the mothers, and most of these results were largely population specific. CONCLUSIONS: Because the consequences of colchicine application are still apparent in the second generation of the plants, at least the third-generation polyploids should be considered in future comparisons. The specificities of the colchicine-treated plants may also be caused by strong selection pressures during the creation of synthetic polyploids. This could be tested by comparing the initial sizes of plants that survived the colchicine treatments with those of plants that did not. High variation between populations also suggests that different polyploids follow different evolutionary trajectories, and this should be considered when studying the effects of polyploidization.

• Klíčová slova
• Anti-mitotic agent, Fabaceae, common garden experiment, flow cytometry, individual growth rate, neopolyploid, reproductive fitness, trait evolution,
• MeSH
• diploidie MeSH
• kolchicin farmakologie   MeSH
• molekulární evoluce MeSH
• polyploidie * MeSH
• tetraploidie MeSH
• vikev účinky léků   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kolchicin MeSH

Vicia cracca diploids and autotetraploids are highly parapatric in Europe; tetraploids reside in western and northern part, whereas diploids occupy much drier south-eastern part. They meet together in a Central European contact zone. This distribution pattern raised questions about a transformative effect of polyploidization on plant performance and environmental tolerances. We investigated plant survival, growth, and seed production in two water regimes in a common garden experiment using seeds collected from five localities in the Central European contact zone where diploids and tetraploids occur in sympatry. Obtained data imply that tetraploids of V. cracca are not generally superior in performance to diploids. Significantly larger seeds from tetraploid mother plants collected in the field were not correlated with greater stature of the seedlings. Nonetheless, tetraploids might have a potential to out-compete diploids in the long run due to the tetraploids' ability of greater growth which manifested in the second year of cultivation. Considering the response of diploids and tetraploids to water supply, drought stressed tetraploids but not diploids produced a higher proportion of aborted seeds than watered ones, which implies that tetraploids are more drought susceptible than diploids. On the other hand, decreased plant height in drought stresses tetraploids, which simultaneously increased total seed production, may suggest that tetraploids have a greater ability to avoid local extinction under unfavourable conditions by enhancing biomass allocation into production of seeds at the cost of lower growth. The significant interaction between ploidy level and locality in several traits suggests possible polyfyletic origin of tetraploids and the necessity to clarify the history of the tetraploids in Europe.

• Klíčová slova
• Drought stress, Polyploid, Seed production, Seed weight, Sympatric, Vegetative growth,
• MeSH
• biomasa MeSH
• diploidie MeSH
• ploidie MeSH
• semena rostlinná genetika   růst a vývoj   MeSH
• semenáček genetika   růst a vývoj   MeSH
• sympatrie MeSH
• tetraploidie MeSH
• vikev genetika   růst a vývoj   MeSH
• zahrady MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Evropa MeSH

BACKGROUND AND AIMS: Polyploidy in plants has been studied extensively. In many groups, two or more cytotypes represent separate biological entities with distinct distributions, histories and ecology. This study examines the distribution and origins of cytotypes of Alnus glutinosa in Europe, North Africa and western Asia. METHODS: A combined approach was used involving flow cytometry and microsatellite analysis of 12 loci in 2200 plants from 209 populations combined with species distribution modelling using MIROC and CCSM climatic models, in order to analyse (1) ploidy and genetic variation, (2) the origin of tetraploid A. glutinosa, considering A. incana as a putative parent, and (3) past distributions of the species. KEY RESULTS: The occurrence of tetraploid populations of A. glutinosa in Europe is determined for the first time. The distribution of tetraploids is far from random, forming two geographically well-delimited clusters located in the Iberian Peninsula and the Dinaric Alps. Based on microsatellite analysis, both tetraploid clusters are probably of autopolyploid origin, with no indication that A. incana was involved in their evolutionary history. A projection of the MIROC distribution model into the Last Glacial Maximum (LGM) showed that (1) populations occurring in the Iberian Peninsula and North Africa were probably interconnected during the LGM and (2) populations occurring in the Dinaric Alps did not exist throughout the last glacial periods, having retreated southwards into lowland areas of the Balkan Peninsula. CONCLUSIONS: Newly discovered tetraploid populations are situated in the putative main glacial refugia, and neither of them was likely to have been involved in the colonization of central and northern Europe after glacial withdrawal. This could mean that neither the Iberian Peninsula nor the western part of the Balkan Peninsula served as effective refugial areas for northward post-glacial expansion of A. glutinosa.

• Klíčová slova
• Alnus glutinosa, autopolyploidy, cytotype distribution, ecological niche models, flow cytometry, glacial refugia, microsatellites,
• MeSH
• alely MeSH
• analýza hlavních komponent MeSH
• diploidie MeSH
• ekosystém * MeSH
• fylogeneze * MeSH
• genetická variace MeSH
• mikrosatelitní repetice genetika   MeSH
• olše cytologie   genetika   MeSH
• polyploidie MeSH
• průtoková cytometrie metody   MeSH
• rostlinné geny MeSH
• zeměpis * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH

Areas of immediate contact of different cytotypes offer a unique opportunity to study evolutionary dynamics within heteroploid species and to assess isolation mechanisms governing coexistence of cytotypes of different ploidy. The degree of reproductive isolation of cytotypes, that is, the frequency of heteroploid crosses and subsequent formation of viable and (partly) fertile hybrids, plays a crucial role for the long-term integrity of lineages in contact zones. Here, we assessed fine-scale distribution, spatial clustering, and ecological niches as well as patterns of gene flow in parental and hybrid cytotypes in zones of immediate contact of di-, tetra-, and hexaploid Senecio carniolicus (Asteraceae) in the Eastern Alps. Cytotypes were spatially separated also at the investigated microscale; the strongest spatial separation was observed for the fully interfertile tetra- and hexaploids. The three main cytotypes showed highly significant niche differences, which were, however, weaker than across their entire distribution ranges in the Eastern Alps. Individuals with intermediate ploidy levels were found neither in the diploid/tetraploid nor in the diploid/hexaploid contact zones indicating strong reproductive barriers. In contrast, pentaploid individuals were frequent in the tetraploid/hexaploid contact zone, albeit limited to a narrow strip in the immediate contact zone of their parental cytotypes. AFLP fingerprinting data revealed introgressive gene flow mediated by pentaploid hybrids from tetra- to hexaploid individuals, but not vice versa. The ecological niche of pentaploids differed significantly from that of tetraploids but not from hexaploids.

• Klíčová slova
• Asymmetric gene flow, Senecio carniolicus (Asteraceae), contact zone, ecological niche, hybrid cytotypes, polyploidy,
• Publikační typ
• časopisecké články MeSH

BACKGROUND AND AIMS: Despite the great importance of autopolyploidy in the evolution of angiosperms, relatively little attention has been devoted to autopolyploids in natural polyploid systems. Several hypotheses have been proposed to explain why autopolyploids are so common and successful, for example increased genetic diversity and heterozygosity and the transition towards selfing. However, case studies on patterns of genetic diversity and on mating systems in autopolyploids are scarce. In this study allozymes were employed to investigate the origin, population genetic diversity and mating system in the contact zone between diploid and assumed autotetraploid cytotypes of Vicia cracca in Central Europe. METHODS: Four enzyme systems resolved in six putative loci were investigated in ten diploid, ten tetraploid and five mixed-ploidy populations. Genetic diversity and heterozygosity, partitioning of genetic diversity among populations and cytotypes, spatial genetic structure and fixed heterozygosity were analysed. These studies were supplemented by a pollination experiment and meiotic chromosome observation. KEY RESULTS AND CONCLUSIONS: Weak evidence of fixed heterozygosity, a low proportion of unique alleles and genetic variation between cytotypes similar to the variation among populations within cytotypes supported the autopolyploid origin of tetraploids, although no multivalent formation was observed. Tetraploids possessed more alleles than diploids and showed higher observed zygotic heterozygosity than diploids, but the observed gametic heterozygosity was similar to the value observed in diploids and smaller than expected under panmixis. Values of the inbreeding coefficient and differentiation among populations (ρST) suggested that the breeding system in both cytotypes of V. cracca is mixed mating with prevailing outcrossing. The reduction in seed production of tetraploids after selfing was less than that in diploids. An absence of correlation between genetic and geographic distances and high differentiation among neighbouring tetraploid populations supports the secondary contact hypothesis with tetraploids of several independent origins in Central Europe. Nevertheless, the possibility of a recent in situ origin of tetraploids through a triploid bridge in some regions is also discussed.

• Klíčová slova
• Autopolyploidy, F-statistics, Vicia cracca, allozymes, artificial pollination, fixed heterozygosity, genetic differentiation, genetic diversity, heterozygosity, inbreeding depression, mating system, meiotic chromosomes,
• MeSH
• alely MeSH
• diploidie * MeSH
• genetická variace * MeSH
• heterozygot MeSH
• izoenzymy genetika   MeSH
• opylení genetika   MeSH
• populační genetika * MeSH
• samooplození genetika   MeSH
• semena rostlinná genetika   MeSH
• tetraploidie * MeSH
• vikev genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Evropa MeSH
• Slovenská republika MeSH
• Názvy látek
• izoenzymy MeSH