Polyploidization is generally considered to be an important evolutionary driver affecting the genetic diversity, that can alter the morphology, phenology, physiology or ecology of plants, which in turn may make the taxonomy of polyploids more difficult. One such example is the Symphytum officinale complex, a polyploid species group represented by three major cytotypes: tetraploids (2n = 48), less common, geographically restricted diploids (2n = 24) and hypotetraploids (2n = 40). In most European floras only one polymorphic species, S. officinale, is widely recognized, while the particular cytotypes are usually considered conspecific. Our study provided a thorough evaluation of the ploidy level diversity, morphological and ecological variation, with a special attempt to clarify the status of 'white-flowered' diploids. Using flow cytometry, we identified three cytotypes: widespread tetraploids (76.1 %); less frequent diploids (23.6 %) with scattered distribution across the range of tetraploids and confined only to several areas of Europe; and extremely rare triploids (0.3 %). Diploids and tetraploids showed diffuse parapatric pattern of distribution, with only four mixed-cytotype populations (2.7 %) found, but almost entirely without triploids, suggesting reproductive isolation between di- and tetraploids. Niche of diploids falls nearly completely within the niche of tetraploids that showed niche expansion. Tetraploids also showed a shift in niche optimum towards a less continental and colder climate, coupled with expansion to more disturbance-prone sites with higher nutrient availability. Diploids were clearly distinguishable morphologically from tetraploids. The morphological differentiation of studied cytotypes appears to be taxonomically significant, especially in combination with ecological differences and the apparent presence of hybridization barriers. Both cytotypes should be treated as separate species (i.e. S. bohemicum and S. officinale s. str.).

• Klíčová slova
• Autopolyploidy, Boraginaceae, cytogeography, flow cytometry, niche modelling, taxonomy,
• 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

The mustard family (Brassicaceae) comprises several dozen monophyletic clades usually ranked as tribes. The tribe Boechereae plays a prominent role in plant research due to the incidence of apomixis and its close relationship to Arabidopsis. This tribe, largely confined to western North America, harbors nine genera and c. 130 species, with >90% of species belonging to the genus Boechera. Hundreds of apomictic diploid and triploid Boechera hybrids have spurred interest in this genus, but the remaining Boechereae genomes remain virtually unstudied. Here we report on comparative genome structure of six genera (Borodinia, Cusickiella, Phoenicaulis, Polyctenium, Nevada, and Sandbergia) and three Boechera species as revealed by comparative chromosome painting (CCP). All analyzed taxa shared the same seven-chromosome genome structure. Comparisons with the sister Halimolobeae tribe (n = 8) showed that the ancestral Boechereae genome (n = 7) was derived from an older n = 8 genome by descending dysploidy followed by the divergence of extant Boechereae taxa. As tribal divergence post-dated the origin of four tribe-specific chromosomes, it is proposed that these chromosomal rearrangements were a key evolutionary innovation underlaying the origin and diversification of the Boechereae in North America. Although most Boechereae genera exhibit genomic conservatism, intra-tribal cladogenesis has occasionally been accompanied by chromosomal rearrangements (particularly inversions). Recently, apomixis was reported in the Boechereae genera Borodinia and Phoenicaulis. Here, we report sexual reproduction in diploid Nevada, diploid Sandbergia, and tetraploid Cusickiella and aposporous apomixis in tetraploids of Polyctenium and Sandbergia. In sum, apomixis is now known to occur in five of the nine Boechereae genera.

• Klíčová slova
• Cruciferae, North America, apomixis, apospory, autopolyploidy, descending dysploidy, karyotype evolution, speciation,
• Publikační typ
• časopisecké články MeSH

This chapter outlines an empirical analysis of genome-wide single-nucleotide polymorphism (SNP) variation and its underlying drivers among multiple natural populations within a diploid-autopolyploid species. The aim is to reconstruct the genetic structure among natural populations of varying ploidy and infer footprints of selection in these populations, framed around specific questions that are typically encountered when analyzing a mixed-ploidy data set,e.g., addressing the relevance of natural whole-genome duplication for speciation and adaptation. We briefly review the options for the analysis of polyploid population genomic data involving variant calling, population structure, demographic history inference, and selection scanning approaches. Further, we provide suggestions for methods and associated software, possible caveats, and examples of their application to mixed-ploidy and autopolyploid data sets.

• Klíčová slova
• Arabidopsis, Autopolyploidy, Genetic variation, Population differentiation, Selection scans,
• MeSH
• aklimatizace MeSH
• diploidie * MeSH
• genomika MeSH
• metagenomika * MeSH
• ploidie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

PREMISE: Whole-genome duplication (WGD) is ubiquitous in plants. Recent reviews and meta-analyses, aiming to understand how such phenotypic transition could facilitate neopolyploid establishment, demonstrated multifarious immediate effects of WGD on fitness and reproductive traits. Yet, little is known about how short-term modifications evolve through time. Such a comparison among new and established polyploid lineages is crucial to understand which effects of WGD promote or impede polyploid survival. METHODS: We performed a meta-analysis to determine how WGD affects morphological, cellular, and fitness traits in autotetraploid individuals compared to their diploid progenitors. We studied how established tetraploids differed from diploids compared to neotetraploids, to further learn about the fate of WGD-associated phenotypic effects during polyploid establishment. RESULTS: The short-term effects of WGD were an increase in size of morphological traits and cells, accompanied by a decrease in fitness and the number of cells. After establishment, the morphological effect persisted, but cellular and fitness components reverted back to the values observed in the diploid ancestors. CONCLUSIONS: Our results suggest that the larger morphology of autotetraploids is not a constraint to establishment. However, other observable effects of genome doubling disappeared with time, suggesting that solving cellular and fitness constraints are critical aspects for polyploid establishment.

• Klíčová slova
• autopolyploidy, cellular evolution, effect size, fitness evolution, gigas effect, morphological evolution, whole-genome duplication,
• MeSH
• diploidie MeSH
• duplikace genu * MeSH
• genom rostlinný * MeSH
• polyploidie MeSH
• tetraploidie MeSH
• Publikační typ
• časopisecké články MeSH
• metaanalýza MeSH
• práce podpořená grantem MeSH

BACKGROUND AND AIMS: Ecological differentiation is recognized as an important factor for polyploid speciation, but little is known regarding whether the ecological niches of cytotypes differ between areas of sympatry and areas where single cytotypes occur (i.e. niche displacement). METHODS: Ecological niches of four groups of Senecio carniolicus sensu lato (s.l.) (western and eastern diploid lineages, tetraploids and hexaploids) were characterized via Landolt indicator values of the accompanying vascular plant species and tested using multivariate and univariate statistics. KEY RESULTS: The four groups of S. carniolicus s.l. were ecologically differentiated mainly with respect to temperature, light and soil (humus content, nutrients, moisture variability). Niche breadths did not differ significantly. In areas of sympatry hexaploids shifted towards sites with higher temperature, less light and higher soil humus content as compared with homoploid sites, whereas diploids and tetraploids shifted in the opposite direction. In heteroploid sites of tetraploids and the western diploid lineage the latter shifted towards sites with lower humus content but higher aeration. CONCLUSIONS: Niche displacement can facilitate the formation of stable contact zones upon secondary contact of polyploids and their lower-ploid ancestors and/or lead to convergence of the cytotypes' niches after they have attained non-overlapping ranges. Niche displacement is essential for understanding ecological consequences of polyploidy.

• Klíčová slova
• Senecio carniolicus s.l., autopolyploidy, biodiversity, coexistence, contact zones, ecological differentiation, range-wide niche displacement, speciation.,
• MeSH
• diploidie MeSH
• ekosystém MeSH
• ekotyp MeSH
• metoda Monte Carlo MeSH
• modely genetické MeSH
• polyploidie * MeSH
• Senecio genetika   fyziologie   MeSH
• sympatrie * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH

UNLABELLED: • PREMISE OF THE STUDY: Contact zones between diploids and their autopolyploid descendants represent a unique evolutionary venue for studying polyploid establishment, cytotype coexistence, and interactions. Here, we examine cytotype coexistence in a diploid-tetraploid contact zone of a perennial herb, Cardamine amara, located north of the Alps by assessing cytotype spatial patterns, ecological divergence, and genetic variation and structure.• METHODS: Flow cytometry was applied to screen DNA ploidy levels in 302 populations (3296 individuals) and the genetic variation of a selection of 25 populations was examined using microsatellite and AFLP markers. Environmental (landscape and climatic) data were analyzed to assess ecological differentiation between the cytotypes.• KEY RESULTS: A parapatric distribution of the cytotypes with a relatively wide (over 100 km in some regions) secondary contact zone was identified. Mixed-ploidy populations, documented for the first time in this species, as well as triploid individuals were found along the diploid-tetraploid borderline. Different climatic requirements of the two main cytotypes were revealed, mirrored in their altitudinal separation. The tetraploids were genetically differentiated from both the diploids and the modeled, in silico autotetraploid genotypes, in accordance with the assumed polyploid origin and spread linked to past glaciations, and largely independent evolution in allopatry.• CONCLUSIONS: The observed spatial and genetic patterns likely reflect the evolutionary and colonization history of the two cytotypes and have been maintained by multiple factors such as ecological divergence, limited gene flow between the cytotypes, and the restricted dispersal capacity.

• Klíčová slova
• AFLPs, Alps, Brassicaceae, autopolyploidy, contact zone, cytotype coexistence, environmental predictors, microsatellites, polyploidy,
• MeSH
• analýza polymorfismu délky amplifikovaných restrikčních fragmentů MeSH
• Cardamine genetika   fyziologie   MeSH
• chromozomy rostlin genetika   MeSH
• diploidie MeSH
• distribuce rostlin * MeSH
• ekosystém * MeSH
• genetická variace * MeSH
• hybridizace genetická MeSH
• mikrosatelitní repetice MeSH
• tetraploidie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH

Introgression allows polyploid species to acquire new genomic content from diploid progenitors or from other unrelated diploid or polyploid lineages, contributing to genetic diversity and facilitating adaptive allele discovery. In some cases, high levels of introgression elicit the replacement of large numbers of alleles inherited from the polyploid's ancestral species, profoundly reshaping the polyploid's genomic composition. In such complex polyploids, it is often difficult to determine which taxa were the progenitor species and which taxa provided additional introgressive blocks through subsequent hybridization. Here, we use population-level genomic data to reconstruct the phylogenetic history of Betula pubescens (downy birch), a tetraploid species often assumed to be of allopolyploid origin and which is known to hybridize with at least four other birch species. This was achieved by modeling polyploidization and introgression events under the multispecies coalescent and then using an approximate Bayesian computation rejection algorithm to evaluate and compare competing polyploidization models. We provide evidence that B. pubescens is the outcome of an autoploid genome doubling event in the common ancestor of B. pendula and its extant sister species, B. platyphylla, that took place approximately 178,000-188,000 generations ago. Extensive hybridization with B. pendula, B. nana, and B. humilis followed in the aftermath of autopolyploidization, with the relative contribution of each of these species to the B. pubescens genome varying markedly across the species' range. Functional analysis of B. pubescens loci containing alleles introgressed from B. nana identified multiple genes involved in climate adaptation, while loci containing alleles derived from B. humilis revealed several genes involved in the regulation of meiotic stability and pollen viability in plant species.

• Klíčová slova
• Allopolyploidy, Betula, autopolyploidy, gene flow, genomic polarization, homoeologs, interploidal, introgressive hybridization, polyploid phylogenetics, polyploidization simulation, reticulate evolution,
• MeSH
• alely * MeSH
• bříza * genetika   klasifikace   MeSH
• fylogeneze * MeSH
• genom rostlinný * MeSH
• genová introgrese MeSH
• hybridizace genetická MeSH
• polyploidie * MeSH
• Publikační typ
• časopisecké články MeSH

Restoring cytonuclear stoichiometry is necessary after whole-genome duplication (WGD) and interspecific/intergeneric hybridization in plants. We investigated this phenomenon in auto- and allopolyploids of the Festuca-Lolium complex providing insights into the mechanisms governing cytonuclear interactions in early polyploid and hybrid generations. Our study examined the main processes potentially involved in restoring the cytonuclear balance after WGD comparing diploids and new and well-established autopolyploids. We uncovered that both the number of chloroplasts and the number of chloroplast genome copies were significantly higher in the newly established autopolyploids and grew further in more established autopolyploids. The increase in the copy number of the chloroplast genome exceeded the rise in the number of chloroplasts and fully compensated for the doubling of the nuclear genome. In addition, changes in nuclear and organelle gene expression were insignificant. Allopolyploid Festuca × Lolium hybrids displayed potential structural conflicts in parental protein variants within the cytonuclear complexes. While biased maternal allele expression has been observed in numerous hybrids, our results suggest that its role in cytonuclear stabilization in the Festuca × Lolium hybrids is limited. This study provides insights into the restoration of the cytonuclear stoichiometry, yet it emphasizes the need for future research to explore post-transcriptional regulation and its impact on cytonuclear gene expression stoichiometry. Our findings may enhance the understanding of polyploid plant evolution, with broader implications for the study of cytonuclear interactions in diverse biological contexts.

• Klíčová slova
• Festuca pratensis Huds., Lolium multiflorum lam., allopolyploidy, autopolyploidy, chloroplast, cytonuclear interactions, gene expression, organelle DNA, protein modeling, whole genome duplication,
• MeSH
• buněčné jádro * genetika   metabolismus   MeSH
• chloroplasty genetika   metabolismus   MeSH
• Festuca * genetika   MeSH
• genom chloroplastový MeSH
• genom rostlinný genetika   MeSH
• hybridizace genetická MeSH
• jílek * genetika   MeSH
• polyploidie * MeSH
• regulace genové exprese u rostlin MeSH
• Publikační typ
• časopisecké články MeSH

PREMISE OF THE STUDY: After decades of interest, the contribution of hybridization to ecological diversification remains unclear. Hybridization is a potent source of novelty, but nascent hybrid lineages must overcome reproductive and ecological competition from their parental species. Here, we assess whether hybrid speciation is advantageous over alternative modes of speciation, by comparing the geographical and ecological ranges and climatic niche evolutionary rates of stabilized allopolyploid vs. autopolyploids in the Alyssum montanum species complex. METHODS: We combined an extensive review of studies addressing the systematics and genetic diversity of A. montanum s.l., with flow cytometry and cloning of nuclear markers, to establish the ploidy level and putative hybrid nature of 205 populations. The respective geographic distribution and climatic niche evolution dynamics of the allo- and autopolyploids were investigated using multivariate analyses and comparative phylogenetic approaches. KEY RESULTS: As expected by theory, allopolyploids occur mainly along contact zones and are generally spatially overlapping with their diploid counterparts. However, they demonstrate higher rates of niche evolution and expand into different climatic conditions than those of their diploid congeners. In contrast, autopolyploids show lower rates of niche evolution, occupy ecological niches similar to their ancestors and are restricted to less competitive and peripheral geographic areas. CONCLUSIONS: Hybridization thus seems advantageous by promoting ecological niche evolution and more readily allowing escape from competitive exclusion.

• Klíčová slova
• Brassicaceae, allopolyploidy, autopolyploidy, competition, diversification, ecological novelty, local adaptation, minority cytotype disadvantage, transgressive segregation,
• MeSH
• biologická evoluce MeSH
• Brassicaceae genetika   MeSH
• diploidie MeSH
• ekologie MeSH
• fylogeneze MeSH
• genetická variace * MeSH
• hybridizace genetická * MeSH
• ploidie * MeSH
• podnebí MeSH
• zeměpis MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH