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Background: The genus Allium is known for its high chromosomal variability, but most chromosome counts are based on a few individuals and genome size (GS) reports are limited in certain taxonomic groups. This is evident in the Allium sect. Codonoprasum, a species-rich (> 150 species) and taxonomically complex section with weak morphological differences between taxa, the presence of polyploidy and frequent misidentification of taxa. Consequently, a significant proportion of older karyological reports may be unreliable and GS data are lacking for the majority of species within the section. This study, using chromosome counting and flow cytometry (FCM), provides the first comprehensive and detailed insight into variation in chromosome number, polyploid frequency and distribution, and GS in section members, marking a step towards understanding the unresolved diversification and evolution of this group. Results: We analysed 1578 individuals from 316 populations of 25 taxa and reported DNA ploidy levels and their GS, with calibration from chromosome counts in 22 taxa. Five taxa had multiple ploidy levels. First estimates of GS were obtained for 16 taxa. A comprehensive review of chromosome number and DNA-ploidy levels in 129 taxa of the section revealed that all taxa have x = 8, except A. rupestre with two polyploid series (x = 8, descending dysploidy x = 7), unique for this section. Diploid taxa dominated (72.1%), while di- & polyploid (12.4%) and exclusively polyploid (15.5%) taxa were less common. Ploidy diversity showed that diploid taxa dominated in the eastern Mediterranean and decreased towards the west and north, whereas only polyploid cytotypes of di- & polyploid taxa or exclusively polyploid taxa dominated in northern and northwestern Europe. A 4.1-fold variation in GS was observed across 33 taxa analysed so far (2C = 22.3–92.1 pg), mainly due to polyploidy, with GS downsizing observed in taxa with multiple ploidy levels. Intra-sectional GS variation suggests evolutionary relationships, and intraspecific GS variation within some taxa may indicate taxonomic heterogeneity and/or historical migration patterns. Conclusions: Our study showed advantages of FCM as an effective tool for detecting ploidy levels and determining GS within the section. GS could be an additional character in understanding evolution and phylogenetic relationships within the section. [ABSTRACT FROM AUTHOR]

The genus Erigeron (Asteraceae) includes several widely distributed invasive species for which data on chromosome numbers and cytological variation are lacking in many parts of their introduced range. In this study, we targeted five alien Erigeron taxa occurring in Poland to test their chromosome numbers in the context of cytological diversity and invasiveness. In addition, we included three native taxa of the E. acris s. l. complex which are also cytogeographically poorly recognised. To count chromosomes, we made stained microscopic preparations from root tip samples obtained from seedlings or mature plants. Among alien taxa, we documented diploids (2n = 2x = 18) in E. canadensis and E. ×huelsenii (a hybrid between E. acris and E. canadensis), triploids (2n = 3x = 27) in E. annuus, triploids and tetraploids (2n = 4x = 36) in E. strigosus, and hexaploids (2n = 6x = 54) in E. sumatrensis. In the case of native taxa, we found diploids (2n = 2x = 18) in E. acris subsp. acris, E. acris subsp. podolicus and E. muralis. We also showed that the karyotype of E. ×huelsenii includes two sets of chromosomes differing in size, reflecting the difference in the amount of nuclear DNA between its parental species. However, this hybrid appears to be a weak competitor due to its sterility, lack of vegetative propagation and short lifespan. Moreover, our results confirm that E. strigosus can be cytologically diverse even in one small geographical region in its introduced range. Further studies are needed to prove the effects of hybridisation and polyploidy on competitive abilities in alien Erigeron species. [ABSTRACT FROM AUTHOR]

Premise: Polyploidy is a major factor in plant adaptation and speciation. Multiple mechanisms contribute to autopolyploid frequency within populations, but uncertainties remain regarding mechanisms that facilitate polyploid establishment and persistence. Here we aimed to document and predict cytotype distributions of Oxalis obliquifolia Steud. ex A. Rich. across Gauteng, South Africa, and test for evidence of possible mechanisms, including morphological, phenological, and reproductive traits, that may potentially facilitate polyploid persistence. Methods: Over 320 O. obliquifolia plants from 25 sites were cytotyped using flow cytometry, and DNA ploidy was confirmed using meiotic chromosome squashes. Cytotypes were mapped and correlations with abiotic variables assessed using ordinations. To assess morphological and phenological associations with cytotype, we grew multiple cytotypes in a common garden, measured phenotypic traits and compared them using linear models and discriminant analyses. Intercytotype reproductive isolation was assessed using crossing experiments, and AMOVAs based on ITS DNA sequences tested for cytogeographic structure. Results: Six cytotypes were identified, and most sites had multiple cytotypes. Abiotic variables were not predictive of cytotype distribution. A clear gigas effect was present. Differences in flower size and phenology suggested pollinator interactions could play a role in polyploid persistence. Intercytotype crosses produced seed at low frequency. DNA data suggested diploids and polyploids were largely reproductively isolated in situ, and polyploidization events were not frequent enough to explain high cytotype sympatry. Conclusions: Diploids and polyploids are behaving as separate species, despite little observable niche differentiation and non‐zero potential intercytotype seed set. Tests on biotic interactions and intercytotype F1 fitness may provide insights into diploid and polyploid coexistence. [ABSTRACT FROM AUTHOR]

Polyploidization is pivotal in plant speciation, affecting adaptability, ecological tolerance and specific geographical distribution patterns. While cytotype diversity has been extensively studied in angiosperms and ferns, knowledge in homosporous lycophytes remains very limited. Our study addresses this gap, focusing on the homosporous lycophyte Huperzia selago in Central Europe. The genome size of 1330 individuals from 208 populations were assessed via flow cytometry, revealing five distinct cytotypes (2x, 3x, 4x, 5x, 6x). Challenging chromosome counting using gemmae roots yielded average counts of 140 (2x), 204 (3x), and 262 (4x) chromosomes. The hexaploid genome size (29 pg) approached the upper limits reported for lycophytes. Tetraploids were the most abundant (72.7%), while triploids (21.3%) were less common, while the remaining cytotypes comprised less than 5% of the dataset. Geographical separation of cytotypes was not observed. However, uncommon cytotypes were associated with the Alps and triploids also occured in the highest parts of Western Carpathians. Around 27.3% of populations exhibited multiple cytotypes. Except for atypical diploids, spore abortion differed between even (21.8%) and odd ploidies (65.2%). Microcharacter (stoma, spore) proportions did not linearly correspond with increasing ploidy levels. The high ploidy-level diversity and cytotype coexistence in Central European H. selago match the well documented patterns in ferns and angiosperms. These findings provide valuable insights into lycophyte polyploidy, underscoring the necessity for broader geographical sampling and application of molecular studies to elucidate phylogenetic relationships and taxonomic classifications within the genus Huperzia. [ABSTRACT FROM AUTHOR]

Environmental factors may shape the spatial distribution of ploidy levels. Here, we undertook a cytogeographical study of Rhodohypoxis baurii var. platypetala (Hypoxidaceae), a Drakensberg near‐endemic taxon. We addressed the following questions: (1) Are there mixed‐ploidy populations or is each population represented by a single ploidy level? (2) Is there a pattern in the environmental distribution of ploidy levels? (3) Are there specific environmental variables associated with each ploidy level locality? (4) Are plant traits similar or different within and among ploidy levels across populations that experience different environmental factors? We measured leaf and flower traits of individuals that were sampled for flow cytometry from 17 populations across the KwaZulu‐Natal and Free State provinces in South Africa. We extracted daily climate data for 13 variables and collected soil samples to evaluate pH and nutrient properties to characterize the sampled populations to test for relationships with ploidy level distributions. Twelve populations were found to contain only diploids, four populations contained only tetraploids, and only one population was 'mixed ploidy' (both diploid and triploid individuals present). There was an overlap in the altitudinal range of diploid and tetraploid populations, but diploids reached the highest altitudes recorded for the current study. We also found that R. baurii var. platypetala occurs in acidic soils and that tetraploids occurred in soils with marginally higher nitrogen and phosphorus than soils where diploids occur. Tetraploids generally occurred in warmer conditions, in drier soils, and possessed broader leaves and larger flowers than diploids. Our study suggests that soil factors and temperature at a small (within localities) spatial scale likely shape ploidy level distributions in the Drakensberg grasslands. [ABSTRACT FROM AUTHOR]

Introduction: Despite the wealth of studies dealing with the invasions of alien plants, invasions of alien genotypes of native species (cryptic invasions) have been vastly neglected. The impact of cryptic invasions on the biodiversity of plant communities can, however, be significant. Inland saline habitats and halophytes (i.e., salt-tolerant plant species) are especially threatened by this phenomenon as they inhabit fragmented remnants of largely destroyed habitats, but at the same time some of these halophytic species are rapidly spreading along salt-treated roads. To study potential cryptic invasion of halophytes, the patterns of genome size and ploidy variation in the Puccinellia distans complex (Poaceae), the most rapidly spreading roadside halophyte in Central Europe, were investigated. Methods: DNA flow cytometry with confirmatory chromosome counts were employed to assess ploidy levels of 1414 individuals from 133 populations of the P. distans complex. In addition, climatic niche modelling was used to predict the distributions of selected cytotypes. Results: Eight groups differing in ploidy level and/or genome size were discovered, one diploid (2x; 2n = 14), two tetraploid (4xA, 4xB; 2n = 28), one pentaploid (5x; 2n = 35), three hexaploid (6xA, 6xB, 6xC; 2n = 42), and one heptaploid (7x; 2n = 49). The hexaploids (mostly the 6xC cytotype) were widespread through the study area, spreading intensively in both anthropogenic and natural habitats and probably hybridizing with the natural habitat dwelling tetraploids. In contrast, the non-hexaploid cytotypes rarely spread and were predominantly confined to natural habitats. Discussion: The extensive spread of the hexaploid cytotypes along roadsides has most likely facilitated their incursion into natural habitats. The colonization of new natural habitats by the hexaploids may pose a threat to the indigenous Puccinellia populations by compromising their genetic integrity and/or by outcompeting them. [ABSTRACT FROM AUTHOR]

IntroductionDespite the wealth of studies dealing with the invasions of alien plants, invasions of alien genotypes of native species (cryptic invasions) have been vastly neglected. The impact of cryptic invasions on the biodiversity of plant communities can, however, be significant. Inland saline habitats and halophytes (i.e., salt-tolerant plant species) are especially threatened by this phenomenon as they inhabit fragmented remnants of largely destroyed habitats, but at the same time some of these halophytic species are rapidly spreading along salt-treated roads. To study potential cryptic invasion of halophytes, the patterns of genome size and ploidy variation in the Puccinellia distans complex (Poaceae), the most rapidly spreading roadside halophyte in Central Europe, were investigated.MethodsDNA flow cytometry with confirmatory chromosome counts were employed to assess ploidy levels of 1414 individuals from 133 populations of the P. distans complex. In addition, climatic niche modelling was used to predict the distributions of selected cytotypes.ResultsEight groups differing in ploidy level and/or genome size were discovered, one diploid (2x; 2n = 14), two tetraploid (4xA, 4xB; 2n = 28), one pentaploid (5x; 2n = 35), three hexaploid (6xA, 6xB, 6xC; 2n = 42), and one heptaploid (7x; 2n = 49). The hexaploids (mostly the 6xC cytotype) were widespread through the study area, spreading intensively in both anthropogenic and natural habitats and probably hybridizing with the natural habitat dwelling tetraploids. In contrast, the non-hexaploid cytotypes rarely spread and were predominantly confined to natural habitats.DiscussionThe extensive spread of the hexaploid cytotypes along roadsides has most likely facilitated their incursion into natural habitats. The colonization of new natural habitats by the hexaploids may pose a threat to the indigenous Puccinellia populations by compromising their genetic integrity and/or by outcompeting them.

The genetic systems of Paspalum species have not been extensively studied. We analyzed the ploidy, reproductive mode, mating system, and fertility of four Paspalum species—Paspalum durifolium, Paspalum ionanthum, Paspalum regnellii, and Paspalum urvillei. An analysis of 378 individuals from 20 populations of northeastern Argentina was conducted. All populations of the four Paspalum species were pure tetraploid and had a sexual and stable reproductive mode. However, some populations of P. durifolium and P. ionanthum showed low levels of apospory. Populations of P. durifolium and P. ionanthum had low seed sets under self-pollination but were fertile under open pollination, showing that self-incompatibility likely caused self-sterility. In contrast, populations of P. regnellii or P. urvillei showed no evidence of apospory, and seed sets in both self- and open pollination conditions were high, suggesting that they are self-compatible due to the absence of pollen–pistil molecular incompatibility mechanisms. The evolutionary origin of the four Paspalum species could explain these differences. This study supplies valuable insights into the genetic systems of Paspalum species, which could have implications for their conservation and management. [ABSTRACT FROM AUTHOR]

Turnera sidoides (x=7) is one of the few well-studied South American autopolyploid complexes. Since polyploidy has played a prominent role within this complex, ongoing studies in T. sidoides focus on understanding the mechanisms involved in the origin and the establishment of polyploids using integrative approaches. This paper synthesises the results of more than 20 years of research on this topic. Cytogenetics analysis provided evidences for the production of unreduced male and female gametes, supporting the hypothesis of bilateral sexual polyploidization as the mechanism of origin of polyploids in T. sidoides. The finding of viable triploids suggested that unilateral sexual polyploidization could also be an important mechanism for the origin of tetraploids in T. sidoides. The occurrence of plants continuously forming many unreduced gametes would play a key role in the establishment of neopolyploids in natural populations. Also, the higher number of propagules that tetraploids contribute to subsequent generations, the ability to multiply asexually by rhizomes, and the occurrence of occasional cases of self-compatibility and successful illegitimate crosses in polyploids increase the likelihood that a low frequency of neopolyploids can be maintained in natural populations of T. sidoides. In addition, integration of cytogeographic and genetic divergence data together with past niche modelling provided further insights supporting the hypothesis that historical climatic and geomorphological events provided favourable conditions for the establishment of autopolyploids, with the wider distribution of tetraploids of T. sidoides being the result of their range expansion.

Uniparental reproduction, the capacity of an individual to produce offspring autonomously, is expected to facilitate range expansion of populations. Paspalum spp. reproduce uniparentally by sexual (self-fertility) and asexual (apomixis) reproduction and biparentally by sexual (self-sterility) reproduction. We evaluated the relationship between contrasting reproductive strategies (uni- and biparentality) and their impact on the colonizing ability and geographical range sizes of populations. We determined the cytotype composition of 16 populations of P. indecorum, P. cromyorhizon, P. pumilum and P. maculosum and assessed the sexual (self-fertile and self-sterile) and apomictic proportions by cyto-embryological analyses, fertility rates and seed flow cytometry. Data obtained regarding reproductive modes were compared to the distribution range of each cytotype and species. Sexual diploids with moderate degrees of self-fertility and mixed pollination syndromes showed wider distribution ranges than self-sterile diploids. In sexual diploids, increased rates of self-fertility relate to larger distribution areas. In agamic complexes, self-fertility reduces the differences in range sizes between biparental diploids and uniparental tetraploids. In such complexes, the range size of diploid cytotypes explains the range size and dispersal of apomictic tetraploids. Thus, uniparental reproduction via self-fertility and apomixis describes patterns of geographical parthenogenesis in South American species. [ABSTRACT FROM AUTHOR]

Polyploidy has received considerable interest in the past, but aneuploidy and partial rearrangements may also influence genomic divergence. In this study, we reported a comprehensive cytogeographic, morphological and genetic analysis of Lycoris aurea complex throughout its range and attempted to explore the association between aneuploidy and species diversification. The karyotypes of this complex presented aneuploidy variations mainly divided into four cytotypes: I (2n = 10m + 2T), II (2n = 8m + 6T), III (2n = 7m + 8T), and IV (2n = 6m + 10T). Cytotype distributions were highly structured geographically. Two main cytotypes, II and IV, are geographically allopatric. The populations with cytotype II are mainly distributed in central China and the southern islands of Japan. Cytotypes IV is disjunctly distributed in southwestern and southeastern China. The cytotypes with fewer chromosome numbers tend to occur at high latitudes. For analyzing the phylogeographic pattern and genetic structure of this complex, we sequenced four chloroplast DNA fragments (4,748 bp in total) of 241 individuals from 42 populations. Extremely high diversity of cpDNA haplotypes was found, with genetic diversity index (Hd) being 0.932 and 98.61% of the genetic variation occurring among populations, indicating that this complex has undergone strong intraspecific differentiation. The cytotype II had the highest haplotype diversity (Hd = 0.885), while cytotype IV harbored the highest nucleotide diversity (p = 4.09 x 10-3). We detected significant leaf morphological differences not only between cytotype II and IV but also between west lineage and east lineage within cytotype IV. These results illustrated that aneuploidy contributed to extensive morphological and genetic differentiation in L. aurea complex. It was suggested that L. aurea complex should comprise multiple independent evolutionary lineages, and accurate species delimitation needs to be established further in an integrative taxonomic approach. [ABSTRACT FROM AUTHOR]

The diploid A. glutinosa (L.) Gaertn. is widespread throughout the European continent, except in the Iberian and Balkan Peninsulas where tetraploid populations have been discovered. We focused on the tetraploid species described as A. rohlenae Vít, Douda and Mandák that occupies the western part of the Balkan Peninsula, where it has likely completely replaced the diploid species. While the distribution range of the diploid A. glutinosa s. str. is well known, the exact distribution range of the tetraploid A. rohlenae is unknown. Here, we report the first exact distribution of the tetraploid A. rohlenae and the anticipated hybrid zones in which it is in contact with diploid populations using flow cytometry and morphometrics. Tetraploids are located primarily in the mountainous parts of the study area and towards the lowlands are gradually being replaced by diploids, forming a contact zone. We compare the main morphological characteristics of both species. Due to the geographical proximity of the study species, the morphological differences between them are clear outside the contact zones. However, within the contact zones, we recorded hybridisations that obscure the morphological differences between species, probably due to the presence of triploid hybrids. [ABSTRACT FROM AUTHOR]

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 (2 n = 48), less common, geographically restricted diploids (2 n = 24) and hypotetraploids (2 n = 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.). [ABSTRACT FROM AUTHOR]

The establishment and success of polyploids are thought to often be facilitated by ecological niche differentiation from diploids. Unfortunately, most studies compared diploids and polyploids, ignoring variation in ploidy level in polyploids. To fill this gap, we performed a large-scale study of 11,163 samples from 1,283 populations of the polyploid perennial geophyte Allium oleraceum with reported mixed-ploidy populations, revealed distribution ranges of cytotypes, assessed their niches and explored the pattern of niche change with increasing ploidy level. Altogether, six ploidy levels (3x−8x) were identified. The most common were pentaploids (53.6%) followed by hexaploids (22.7%) and tetraploids (21.6%). Higher cytotype diversity was found at lower latitudes than at higher latitudes (>52° N), where only tetraploids and pentaploids occurred. We detected 17.4% of mixed-ploidy populations, usually as a combination of two, rarely of three, cytotypes. The majority of mixed-ploidy populations were found in zones of sympatry of the participating cytotypes, suggesting they have arisen through migration (secondary contact zone). Using coarse-grained variables (climate, soil), we found evidence of both niche expansion and innovation in tetraploids related to triploids, whereas higher ploidy levels showed almost zero niche expansion, but a trend of increased niche unfilling of tetraploids. Niche unfilling in higher ploidy levels was caused by a contraction of niche envelopes toward lower continentality of the climate and resulted in a gradual decrease of niche breadth and a gradual shift in niche optima. Field-recorded data indicated wide habitat breadth of tetraploids and pentaploids, but also a pattern of increasing synanthropy in higher ploidy levels. Wide niche breadth of tetra- and pentaploids might be related to their multiple origins from different environmental conditions, higher “age”, and retained sexuality, which likely preserve their adaptive potential. In contrast, other cytotypes with narrower niches are mostly asexual, probably originating from a limited range of contrasting environments. Persistence of local ploidy mixtures could be enabled by the perenniality of A. oleraceum and its prevalence of vegetative reproduction, facilitating the establishment and decreasing exclusion of minority cytotype due to its reproductive costs. Vegetative reproduction might also significantly accelerate colonization of new areas, including recolonization of previously glaciated areas.

The establishment and success of polyploids are thought to often be facilitated by ecological niche differentiation from diploids. Unfortunately, most studies compared diploids and polyploids, ignoring variation in ploidy level in polyploids. To fill this gap, we performed a large-scale study of 11,163 samples from 1,283 populations of the polyploid perennial geophyte Allium oleraceum with reported mixed-ploidy populations, revealed distribution ranges of cytotypes, assessed their niches and explored the pattern of niche change with increasing ploidy level. Altogether, six ploidy levels (3 x −8 x) were identified. The most common were pentaploids (53.6%) followed by hexaploids (22.7%) and tetraploids (21.6%). Higher cytotype diversity was found at lower latitudes than at higher latitudes (>52° N), where only tetraploids and pentaploids occurred. We detected 17.4% of mixed-ploidy populations, usually as a combination of two, rarely of three, cytotypes. The majority of mixed-ploidy populations were found in zones of sympatry of the participating cytotypes, suggesting they have arisen through migration (secondary contact zone). Using coarse-grained variables (climate, soil), we found evidence of both niche expansion and innovation in tetraploids related to triploids, whereas higher ploidy levels showed almost zero niche expansion, but a trend of increased niche unfilling of tetraploids. Niche unfilling in higher ploidy levels was caused by a contraction of niche envelopes toward lower continentality of the climate and resulted in a gradual decrease of niche breadth and a gradual shift in niche optima. Field-recorded data indicated wide habitat breadth of tetraploids and pentaploids, but also a pattern of increasing synanthropy in higher ploidy levels. Wide niche breadth of tetra- and pentaploids might be related to their multiple origins from different environmental conditions, higher "age", and retained sexuality, which likely preserve their adaptive potential. In contrast, other cytotypes with narrower niches are mostly asexual, probably originating from a limited range of contrasting environments. Persistence of local ploidy mixtures could be enabled by the perenniality of A. oleraceum and its prevalence of vegetative reproduction, facilitating the establishment and decreasing exclusion of minority cytotype due to its reproductive costs. Vegetative reproduction might also significantly accelerate colonization of new areas, including recolonization of previously glaciated areas. [ABSTRACT FROM AUTHOR]

Premise: Polyploidy may serve to contribute to range size if autopolyploid cytotypes are adapted to differing ecological conditions. This study aims to establish the geographic distribution of cytotypes within the giant goldenrod (Solidago gigantea), and to assess whether cytotypes exhibit differing ecological tolerances and morphology. Methods: A range‐wide set of 629 Solidago gigantea individuals was obtained through field collecting, sampling from herbarium specimens, and incorporating existing chromosome counts. Cytotype of each unknown sample was estimated by observing allele numbers at twelve microsatellite loci, a strategy that was assessed by comparing estimated to known cytotype in 20 chromosome‐counted samples. Abiotic ecological differentiation was assessed for two transitions: diploid‐tetraploid and tetraploid‐hexaploid. Morphological differentiation among cytotypes was assessed. Results: Microsatellite repeat variation accurately estimated cytotype in 85% of samples for which ploidy was known. Applying this approach to samples of unknown ploidy established that the three cytotypes are non‐randomly distributed. Although niche modeling and MANOVA approaches identified significant differences in macro‐climatic conditions for both cytotype transitions, the tetraploid to hexaploid transition was more substantial. Leaf length and width did not differ among cytotypes. Although leaf vestiture exhibited strong trends, no absolute differences were observed among cytotypes. Conclusions: With the largest such study to date, we established niche transitions among giant goldenrod cytotypes of differing magnitudes. Collectively, this suggests that whole‐genome duplication has contributed to Solidago gigantea's large range. [ABSTRACT FROM AUTHOR]

In this contribution, new chromosome data obtained on material collected in Italy are presented. It includes counts from six populations of three taxa within the genus Pulmonaria, two of which are endemic to Italy (P. vallarsae subsp. apennina and P. vallarsae subsp. vallarsae); the other is the widespread European P. officinalis. In addition, two counts from Potentilla detommasii and Stachys thirkei, two eastern Mediterranean species, are also reported. [ABSTRACT FROM AUTHOR]

Polyploidization, a key driver of plant diversification, is believed to have interacted with Pleistocene climatic oscillations and local ecological factors, leading to a complex spatio-ecological mosaic of diploid and polyploid populations. The typical ecogeographic pattern in European plants involves spatially restricted diploids growing in southern regions, interpreted as glacial refugia, and their widespread polyploid derivatives occupying larger and more northerly situated ranges with harsher environments. Whether this is true for individual ploidy-variable groups is, however, largely unknown because we lack sufficiently detailed investigations of ploidy-variable plant groups jointly applying cytological, ecological and genetic methods. We assessed ploidy and genome size variation, elevational and edaphic preferences, and plastid DNA variation within the Minuartia verna aggregate, a group of low-competitive heliophilous plants growing from the Mediterranean to Arctic Europe. Contrary to the expectations, tetraploids have a restricted distribution (Southern Europe) and inhabit a relatively narrow environmental niche. The distribution of diploids, on the other hand, spans the full range of conditions, including climatic (i.e. highest elevations and latitudes) and edaphic extremes (i.e. toxic serpentine and metalliferous substrates). The distribution pattern of the two ploidies could be explained by their distinct evolutionary histories, suggesting expansion of the diploid-dominated haplotype group accompanied by long-term persistence and local differentiation of tetraploids in refugia in the Balkan Peninsula. In summary, our study contradicts the prevailing view of polyploids as successful colonizers of novel and challenging habitats and points to the importance of combining ecological and genetic data when studying ploidy-variable species complexes. [ABSTRACT FROM AUTHOR]

Twenty-three Caltha palustris accessions and ten C. scaposa accessions have been cytologically investigated using the traditional chromosome tableting technique and flow cytometry(FCM), in order to investigate the evolution of C. palustris and C. scaposa in Caltha of Ranunculaceae. C. palustris was found to be a polyploid complex, which contained tetraploids(2n=4x=32), hexaploids(2n=6x=48), and octoploids(2n=8x=64), and C. scaposa were tetraploids(2n=4x=32)and octoploids(2n=8x=64). Tetraploids were common in C. palustris and C. scaposa, however, any diploids were hardly discovered. This finding may be explained by cytotype adaptive differences to the underlying heterogeneity of environmental factors. Most accessions of C. palustris and C. scaposa were from extreme habitats, such as the alpine mountains in the Qinghai-Tibetan Plateau. Ancestral diploids may have existed in this region during glacial periods and colonized most regions at the end of the glaciation cycles. However, individuals with other ploidy levels may gradually replace diploids, because of their increased fitness in changing environment. Moreover, there were two possible evolutionary colonization routes: one from Gansu to Yunnan, and the other from Tibet to Yunnan of China. Molecular phylogeny have shown that C. scaposa is closely related to C. palustris, the chromosome size of C. scaposa is smaller than that of C. palustris, C. scaposa may be a relatively derived evolutionary taxon. More samples need to be analyzed in the future to better elucidate C. scaposa cytogeography because of only ten accessions. [ABSTRACT FROM AUTHOR]

Premise: Although autopolyploidy is common among dominant Great Plains grasses, the distribution of cytotypes within a given species is typically poorly understood. This study aims to establish the geographic distribution of cytotypes within buffalograss (Buchloë dactyloides) and to assess whether individual cytotypes have differing ecological tolerances. Methods: A range‐wide set of 578 B. dactyloides individuals was obtained through field collecting and sampling from herbarium specimens. The cytotype of each sample was estimated by determining allele numbers at 13 simple sequence repeat loci, a strategy that was assessed by comparing estimated to known cytotype in 79 chromosome‐counted samples. Ecological differentiation between the dominant tetraploid and hexaploid cytotypes was assessed with analyses of macroclimatic variables. Results: Simple sequence repeat variation accurately estimated cytotype in 89% of samples from which a chromosome count had been obtained. Applying this approach to samples of unknown ploidy established that diploids and pentaploids are rare, with the common tetraploid and hexaploid cytotypes generally occurring in sites to the north/west (tetraploid) or south/east (hexaploid) portions of the species range. Both MANOVA and niche modeling approaches identified significant but subtle differences in macroclimatic conditions at the set of locations occupied by these two dominant cytotypes. Conclusions: Incorporating chromosome count vouchers and cytotype‐estimated herbarium records allowed us to perform the largest study of cytotype niche differentiation to date. Buffalograss cytotypes differ greatly in frequency, the common tetraploid and hexaploid cytotypes are non‐randomly distributed, and these two cytotypes are subtly ecologically differentiated. [ABSTRACT FROM AUTHOR]

In this contribution, new chromosome data obtained on material collected in Italy are presented. It includes a total of 105 chromosome counts for three populations of Pulmonaria vallarsae A.Kern. subsp. apennina (Cristof. & Puppi) Cecchi & Selvi and for three populations of P. hirta L. [ABSTRACT FROM AUTHOR]

In this contribution, new chromosome data obtained on material collected in Italy are presented. It includes three chromosome counts for Bupleurum baldense Turra, Colchicum lusitanum Brot., and Euphorbia gasparrinii Boiss. subsp. gasparrinii. [ABSTRACT FROM AUTHOR]

Polyploidy, the possession of more than two sets of chromosomes, is a major biological process affecting plant evolution and diversification. In the Cactaceae, genome doubling has also been associated with reproductive isolation, changes in breeding systems, colonization ability, and speciation. Pachycereus pringlei (S. Watson, 1885) Britton & Rose, 1909, is a columnar cactus that has long drawn the attention of ecologists, geneticists, and systematists due to its wide distribution range and remarkable assortment of breeding systems in the Mexican Sonoran Desert and the Baja California Peninsula (BCP). However, several important evolutionary questions, such as the distribution of chromosome numbers and whether the diploid condition is dominant over a potential polyploid condition driving the evolution and diversity in floral morphology and breeding systems in this cactus, are still unclear. In this study, we determined chromosome numbers in 11 localities encompassing virtually the entire geographic range of distribution of P. pringlei. Our data revealed the first diploid (2n = 22) count in this species restricted to the hermaphroditic populations of Catalana (ICA) and Cerralvo (ICE) Islands, whereas the tetraploid (2n = 44) condition is consistently distributed throughout the BCP and mainland Sonora populations distinguished by a non-hermaphroditic breeding system. These results validate a wider distribution of polyploid relative to diploid individuals and a shift in breeding systems coupled with polyploidisation. Considering that the diploid base number and hermaphroditism are the proposed ancestral conditions in Cactaceae, we suggest that ICE and ICA populations represent the relicts of a southern diploid ancestor from which both polyploidy and unisexuality evolved in mainland BCP, facilitating the northward expansion of this species. This cytogeographic distribution in conjunction with differences in floral attributes suggests the distinction of the diploid populations as a new taxonomic entity. We suggest that chromosome doubling in conjunction with allopatric distribution, differences in neutral genetic variation, floral traits, and breeding systems has driven the reproductive isolation, evolution, and diversification of this columnar cactus. [ABSTRACT FROM AUTHOR]

In this contribution new chromosome data obtained on material collected in Italy are presented. It includes 7 chromosome counts for Centaurea (Asteraceae). [ABSTRACT FROM AUTHOR]

The pantropical Caesalpinia group comprises 27 genera and approximately 205 species. The Neotropical species of the group are distributed in three main centers of diversity: the Andes, Mesoamerica (including Mexico, Central America, the southern USA and the Caribbean), and Northeastern Brazil. Our study investigates patterns of phylogenetic, environmental and geographical variation in an attempt to explain the karyotypic diversity which occurs within the Caesalpinia group. Cytogenetic analyses were based on chromosome number and morphology, CMA and DAPI heterochromatic bands, distribution of rDNA sites, and their molecular phylogenetic relationships based on the plastid markers mat K, rps 16, trn DT, trn L and ycf 6 and the nuclear ribosomal marker ITS. Ecological differentiation among cytotypes was tested by comparing sets of climatic variables. In total, twenty species from ten genera of the Caesalpinia group were analysed, and all of them were found to have the same chromosome number (2 n = 24). CMA + /DAPI − bands were observed on the short arms of the acrocentric chromosomes in all of the species. Additionally, three different patterns were observed on the metacentric chromosomes: proximal CMA + /DAPI − bands, proximal CMA 0 /DAPI − bands and terminal CMA + /DAPI − bands. The 45S rDNA sites varied from eight to 14, always co-localizing with CMA + /DAPI − bands of acrocentrics, while 5S rDNA was localized in only a single chromosome pair in most species. A correlation between heterochromatic patterns and the geographic distributions/ecological niche of species was observed. Our analyses support some shared effects of the environment, when integrated with phylogeny and geography, on the CMA/DAPI variability. Thus, CMA + heterochromatin is highly dynamic and its amplification/deamplification might be non-random, generating similar karyotypes in species which are not sister taxa in the molecular phylogeny but which co-occur in similar environments. [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY: Detailed knowledge about the karyological diversity of organisms undoubtedly represents one of the crucial steps toward a better understanding of their evolutionary trends and history. We investigated the cytotype and absolute genome size (AGS) patterns in the European mountaindwelling genus Soldanella (Primulaceae) in light of its geographic distribution and ecological diversification. METHODS: Our chromosome number survey was based on 34 newly determined and 125 previously published chromosome counts. AGS was estimated on the basis of propidium iodide (PI) flow cytometry (299 individuals, 110 populations). KEY RESULTS: We confirmed the existence of two cytotypes with the same ploidy level, i.e., euploid 2n = 40 and dysploid 2n = 38. The overall infrageneric AGS variation ranged between 2.97 and 3.99 pg (25.6% variation). The 2 n = 40 cytotype harbors a modest amount of continuous AGS variation. With regard to its distribution area and ecology, the cytotype is ubiquitous. By contrast, the 2 n = 38 cytotype was detected only in six forest-dwelling taxa with AGS variation segregated into three discrete, geographically separated groups. The AGS variation of the 2 n = 38 cytotype was strongly correlated with elevation and longitude. CONCLUSIONS: Despite the apparent morphological and ecological variation, members of the genus Soldanella have not undergone any pronounced cytotype and AGS diversification during their evolutionary history. The lack of correlation between chromosome numbers and AGS indicates that the evolutionary mechanism behind the origin of the dysploid cytotype 2n = 38 was a chromosomal fusion. [ABSTRACT FROM AUTHOR]

The geographic distributions of polyploids suggest they can have distinct and sometimes broader niches compared to diploids. However, relatively few field experiments have investigated whether range differences are associated with local adaptation or reflect other processes, such as dispersal limitation. In three years of transplants across the elevational ranges of five cytotypes in the Claytonia perfoliata complex, we found evidence for local adaptation. In at least one study year germination was higher within the natural range for each cytotype, and four of the five cytotypes attained larger biomass within their natural range. Fitness within and beyond range varied across years, with two instances of cytotypes showing higher fitness beyond the range, highlighting a potential role of temporal variability in cytotype differentiation. Polyploids as a group did not outperform diploids, but the cytotype with highest fitness across environments was a hexaploid reported to be invasive. Our results suggest that differences in geographic ranges within the C. perfoliata complex reflect local adaptation of cytotypes. Although we did not find a general polyploid advantage, our findings support the idea that occasional polyploid cytotypes exhibit high fitness relative to other cytotypes, and contribute to growing evidence supporting ecological differentiation of cytotypes within polyploid complexes. [ABSTRACT FROM AUTHOR]

In this contribution new chromosome data obtained on material collected in Italy are presented. It includes 9 chromosome counts for Polygala (Polygalaceae), Dianthus and Silene (Caryophyllaceae). [ABSTRACT FROM AUTHOR]

Ｓｕｂｇｅｎｕｓ Ａｎｇｕｉｎｕｍ ｂｅｌｏｎｇｓ ｔｏ ｇｅｎｕｓ Ａｌｌｉｕｍ Ｌ．， ｔｒｉｂｅ Ａｌｌｉｅａｅ Ｄｕｍｏｒｔ，ｓｕｂｆａｍｉｌｙ Ａｌｌｉｏｉｄｅａｅ Ｈｅｒｂ．， ｆａｍｉｌｙ Ａｍａｒｙｌｌｉｄａｃｅａｅ Ｊ． Ｓｔ．⁃Ｈｉｌ． Ｓｉｘ ｓｐｅｉｃｅｓ ａｎｄ ｔｗｏ ｖａｒｉｅｔｙ ｓｐｅｃｉｅｓ ｉｎ ｔｈｉｓ ｓｕｂｇｅｎｕｓ ｏｃｃｕｒ ｉｎ Ｅａｓｔ Ａｓｉａｎ． Ｔｈｅｙ ａｒｅ ｉｍｐｏｒｔａｎｔ ｍｅｄｉｃｉｎａｌ ｐｌａｎｔ， ｈａｖｉｎｇ ｇｒｅａｔ ｅｃｏｎｏｍｉｃ ｖａｌｕｅ． Ａｌｌｉｕｍ ｖｉｃｔｏｒｉａｌｉｓ ｈａｓ ｂｅｅｎ ｔｒａｄｉｔｉｏｎａｌｌｙ ｗｉｄｅｌｙ ｕｓｅｄ ｔｏ ｔｒｅａｔ ｖａｒｉｏｕｓ ｃｏｎｄｉ⁃ ｔｉｏｎｓ ｓｕｃｈ ａｓ ｋａｅｍｐｆｅｒｏｌ， ａｃｉｄ， ｄｉａｌｌｙｄｉｓｕｌｆｉｄｅ， ｆｕｒｏｓｔａｎｏｌ ｇｌｙｃｏｓｉｄｅｓ． Ｂｉｏａｃｔｉｖｉｔｙ ｅｘｐｅｒｉｍｅｎｔｓ ｈａｖｅ ｄｅｍｏｎｓｔｒａｔｅｄ ｔｈａｔ ｔｈｅ ｐｌａｎｔ ｉｓ ｅｆｆｅｃｔｉｖｅ ｉｎ ｌｏｗｅｒｉｎｇ ｌｉｐｉｄｓ ａｎｄ ｏｂｅｓｉｔｙ， ｒｅｓｉｓｔｉｎｇ ｏｘｉｄａｔｉｏｎ， ｄｉａｂｅｔｅｓ， ｃａｎｃｅｒ， ａｎｄ ｐｒｏｔｅｃｔｉｎｇ ｔｈｅ ｌｉｖｅｒ． Ｋａｒｙｏｔｙｐｅｓ ｏｆ ｎｉｅｎｔｅｅｎ ｐｏｐｕｌａｔｉｏｎｓ ｏｆ ｆｏｕｒ ｓｐｅｃｉｅｓ ｉｎ Ａｌｌｉｕｍ ｓｕｂｇｅｎｕｓ Ａｎｇｕｉｎｕｍ ｆｒｏｍ Ｃｈｉｎａ ｗｅｒｅ ａｎａｌｙｚｅｄ ｔｏ ｄｉｓｃｕｓｓ ｔｈｅ ｅｖｏｌｕｔｉｏｎａｒｙ ｍｅｃｈａｎｉｓｍｓ ｏｆ Ａｌｌｉｕｍ ｓｕｂｇｅｎｕｓ Ａｎｇｕｉｎｕｍ ａｎｄ ｃｙｔｏｇｅｏｇｒａｐｈｙ ｏｆ Ａｌｌｉｕｍ ｖｉｃｔｏｒｉａｌｉｓ， Ａ． ｌｉｓｔｅｒａ ａｎｄ Ａ． ｐｒａｔｔｉｉ． Ｋａｒｙｏｔｙｐｅｓ ｏｆ Ａ． ｏｖａｌｉｆｏｌｉｕｍ ｖａｒ． ｃｏｒｄｉｆｏｌｉｕｍ ｗａｓ ｒｅｐｏｒｔｅｄ ｆｏｒ ｔｈｅ ｆｉｒｓｔ ｔｉｍｅ． Ｒｏｏｔ ｔｉｐｓ ｆｏｒ ｔｈｅ ｓｔｕｄｙ ｏｆ ｍｉｔｏｔｉｃ ｃｈｒｏｍｏｓｏｍｅｓ ｗｅｒｅ ｏｂｔａｉｎｅｄ ｆｒｏｍ ｐｏｔｔｅｄ ｐｌａｎｔｓ ａｎｄ ｐｒｅｔｒｅａｔｅｄ ｗｉｔｈ ｐａｒａｄｉｃｈｌｏｒｏｂｅｎｚｅｎｅ ａｔ ｒｏｏｍ ｔｅｍｐｅｒａｔｕｒｅ ｆｏｒ ９ ｈ．Ａｆｔｅｒ １２－２４ ｈ ｆｉｘａｔｉｏｎ ｉｎ １ ∶ ３ ａｃｅｔｉｃ⁃ａｌｃｏｈｏｌ， ｔｈｅ ｒｏｏｔ ｔｉｐｓ ｗｅｒｅ ｍａｃｅｒａｔｅｄ ｉｎ １ ｍｏｌ·Ｌ⁃１ ＨＣＬ ｆｏｒ ９ ｍｉｎ ａｔ ６０ ℃， ｔｈｅｎ ｓｔａｉｎｅｄ ａｎｄ ｓｑｕａｓｈｅｄ ｉｎ ｃａｒｂｏｌ ｆｕｃｈｓｉｎ， ａｎｄ ｔｈｅｎ Ｋａｒｙｏｔｙｐｅ ａｓｙｍｍｅｔｒｙ ｗａｓ ａｓｓｅｓｓｅｄ ｂｙ Ａｓ．Ｋ％． Ｔｈｅ ｒｅｓｕｌｔｓ ｓｈｏｗｅｄ ｔｈａｔ ｔｈｅ ｋａｒｙｏｔｙｐｅｓ ｏｆ ａｌｌ ｔｈｅ ｓｐｅｃｉｅｓ ｉｎｖｅｓｔｉｇａｔｅｄ ｗｅｒｅ ２Ａ ａｃｃｏｒｄｉｎｇ ｔｏ Ｓｔｅｂｂｉｎｓ’ ｋａｒｙｏｔｙｐｅ ｃｌａｓｓｉｆｉｃａｔｉｏｎ， ａｎｄ ｔｈｅ ｂａｓｉｃ ｃｈｒｏｍｏｓｏｍｅ ｎｕｍｂｅｒ ｉｓ ｘ ＝ ８． Ａｌｌ ｔｈｅ ｐｏｐｕｌａｔｉｏｎｓ ｈａｄ ｓａｔｅｌｌｉｔｅ ｃｈｒｏｍｏｓｏｍｅｓ， ａｎｄ ｍｏｓｔ ｏｆ ｔｈｅ ｓａｔｅｌｌｉｔｅ ｃｈｒｏｍｏｓｏｍｅｓ ｗｅｒｅ ｓｕｂｔｅｒｍｉｎａｌ ｃｈｒｏｍｏｓｏｍｅｓ ａｎｄ ｓａｔｅｌｌｉｔｅｓ ｗｅｒｅ ｌｏｃａｔｅｄ ｉｎ ｔｈｅ ｓｈｏｒｔ ａｒｍ． Ｃｏｍｂｉｎｅｄ ｗｉｔｈ ｐｒｅｖｉｏｕｓ ｓｔｕｄｉｅｓ， ｏｕｒ ｉｎｆｅｒｅｎｃｅｓ ａｒｅ ａｓ ｆｏｌｌｏｗｓ： （１） Ｐｏｌｙｐｌｏｉｄｙ ａｎｄ ｃｈｒｏｍｏｓｏｍｅ ｓｔｒｕｃｔｕｒａｌ ｒｅａｒｒａｎｇｅｍｅｎｔ ａｒｅ ｔｗｏ ｉｍｐｏｒｔａｎｔ ｅｖｏｌｕｔｉｏｎ ｐａｔｔｅｒｎｓ ｉｎ Ａｌｌｉｕｍ ｓｕｂｇｅｎｕｓ Ａｎｇｕｉｎｕｍ， ａｎｄ ｅｎｖｉｒｏｎｍｅｎｔａｌ ｈｅｔｅｒｏｇｅｎｅｉｔｙ ｐｒｏｍｏｔｅｓ ｔｈｅ ｖａｒｉａｔｉｏｎ ｉｎ ｓａｔｅｌｌｉｔｅ ｃｈｒｏｍｏｓｏｍｅｓ． （２） Ｐｏｌｙｐｌｏｉｄｙ ａｎｄ ａｓｅｘｕａｌ ｒｅｐｒｏｄｕｃｔｉｏｎ ａｒｅ ｉｍｐｏｒｔａｎｔ ｓｔｒａｔｅｇｉｅｓ ｆｏｒ Ａｌｌｉｕｍ ｖｉｃｔｏｒｉａｌｉｓ ｔｏ ｄｉｓｐｅｒｓｅ ａｎｄ ｅｘｐｌｏｉｔ ｎｅｗ ｎｉｃｈｅｓ． （３） Ａ． ｌｉｓｔｅｒａ ｅｘｐａｎｄｓ ｐｏｐｕｌａｔｉｏｎ ｂｙ ｃｈｒｏｍｏｓｏｍｅ ｓｔｒｕｃｔｕｒａｌ ｒｅａｒｒａｎｇｅｍｅｎｔ． [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY: Unrecognized variation in ploidy level can lead to an underestimation of species richness and a misleading delineation of geographic range. Caltha leptosepala (Ranunculaceae) comprises a complex of hexaploids (6 x), rare nonaploids (9 x), and dodecaploids (12 x), all with unknown distributions. We delineate the geographic distribution and contact zones of the cytotypes, investigate morphologies of cytotypes and subspecies, and discuss the biogeography and evolutionary history of the polyploid complex. METHODS: Using cytologically determined specimens as reference, propidium iodide flow cytometry was performed on silica-dried samples and herbarium specimens from across the range of C. leptosepala s.l. Genome size estimates from flow cytometry were used to infer cytotypes. A key morphological character, leaf length-to-width ratio, was measured to evaluate whether these dimensions are informative for taxon and/or cytotype delimitation. KEY RESULTS: Dodecaploids were more northerly in distribution than hexaploids, and a single midlatitude population in the Northern Rockies yielded nonaploids. Genome size estimates were significantly different between all cytotypes and between hexaploid subspecies. Leaf length-to-width ratios were significantly different between subspecies and some cytotypes. CONCLUSIONS: Caltha leptosepala presents clear patterns of cytotype distribution at the large scale. Marked differences in morphology, range, and genome size were detected between the hexaploid subspecies, C. leptosepala subsp. howellii in the Cascade-Sierra axis and C. leptosepala subsp. leptosepala in the Rockies. Sympatry between cytotypes in the Cascades and a parapatric distribution in the Northern Rockies suggest unique origins and separate lineages in the respective contact zones. [ABSTRACT FROM AUTHOR]

In this contribution new chromosome data obtained from material collected in Italy are presented. It includes four chromosome counts for the following genera: Bellevalia (Asparagaceae), Genista (Fabaceae), Linaria (Plantaginaceae), and Teucrium (Lamiaceae). [ABSTRACT FROM AUTHOR]

Oxalis section Articulatae Knuth (Oxalidaceae) comprises a group of five species with a restricted distribution in the southern part of South America. To assess the current circumscription of section Articulatae and the evolutionary mechanisms involved in its diversification, we used three plastid DNA sequences and the nuclear ribosomal transcribed spacer (ITS) to build a molecular phylogeny. A cytogenetic analysis of the group including chromosome number, heterochromatin distribution and determination of nuclear DNA content was also performed. Cytologically, all species presented symmetrical karyotypes except for O. linarantha with a bimodal karyotype although it maintained the same haploid number as the other species ( n = 7). Nuclear DNA contents in the Articulatae species are among the lowest for the genus. The O. linarantha 2C value represents the minimum value known for Oxalis, extending the genome size range from 0.58 to 41.10 pg, representing approximately a 70-fold difference, and one of the highest ranges known for an angiosperm genus. Molecular, chromosomal and morphological data suggest that section Articulatae should be redefined to include only those species with rhizomatous stems while the tunicate-bulbous species O. linarantha should be placed elsewhere. Different ploidy levels were found, ranging from 2 x to 7 x. Diploids and polyploids showed a geographic structure; diploids are widely distributed, while polyploids are found in the uplands of eastern Uruguay and southern Brazil. Haplotype sharing and chromosome data suggest that at least some of section Articulatae polyploids may be the result of interspecific hybridization and appear to have originated very recently. [ABSTRACT FROM AUTHOR]

The Carpathians are the largest mountain range in Central Europe. Their geographical position, extent, isolation, landscape heterogeneity, well-preserved environment, and relatively low impact of Quaternary glaciations make them of utmost importance for studies on European biodiversity and biogeography. In this review, introducing a Special Issue of the Biological Journal of the Linnean Society, we provide an overview of current research and focus on three main aspects: (1) distribution patterns and species richness including endemism; (2) phylogeographical patterns, inference of major barriers, and divergence areas; and (3) cytological studies and cytogeography inferred from vascular plant polyploid complexes. Our survey shows that, although accurate estimation is not possible for several important taxonomic entities because of unavailable or dispersed data, the Carpathians are a clear hotspot of European diversity for many groups of organisms, such as mammals, breeding birds, amphibians, lichens, and vascular plants. Certain groups, not necessarily those with high species richness, are rich in endemic taxa. This holds mainly for subterranean invertebrates, molluscs, grasshoppers, beetles, spiders, and vascular plants. Distribution patterns of endemic richness vary across taxonomic groups, as well as geographically, reflecting both history and habitat features. In general, the South-Eastern Carpathians have a significantly higher proportion of endemic taxa than the northerly-situated Western Carpathians. Molecular clock-based estimations have provided some insight into the diversification age of the Carpathian biota, including a Tertiary origin for some endemic taxa and lineages, especially those confined to environmentally stable habitats. Distribution patterns, as well as phylogeographical and phylogenetic data, corroborate the persistence of many high-mountain and forest taxa during the Quaternary climatic oscillations, often in multiple spatially delimited areas isolated by physical barriers. Several studies show that the Carpathian massifs played an important role as refugia for rare lineages and/or as stepping stones in migrations. Phylogeographical analysis reveals clear patterns of biogeographical breaks, as well as links, although clear exceptions also confirm that extant distribution patterns are often shaped more by idiosyncratic processes acting at different geological times. Cytogeographical data also uncover several consistent patterns, which probably reflect a deeper evolutionary history. In conclusion, the available data highlight the unique position of the Carpathians in the evolution and preservation of European biota within the European Alpine System. [ABSTRACT FROM AUTHOR]

Turnera krapovickasii is distributed at northwestern Argentina, southern Bolivia and western Paraguay. It presents diploid (2n= 2x= 10) and autotetraploid (2n= 4x= 20) cytotypes. Aiming to interpret the role of autopolyploidy in the evolution of this species, the frequency and spatial distribution of the cytotypes were analyzed. Equal frequencies of diploid and tetraploid populations were detected; most of them are constituted by only one cytotype, although some diploid populations presented triploid or tetraploid individuals. Diploids occupy a continuous area from southern Bolivia to northwestern Argentina, and from 124 to 1342 m.a.s.l. Tetraploids occur in disjunct areas, in Eastern and northern species area, in altitudes from 237 up to 810 m.a.s.l. The PCA showed a significant association between cytotype distribution and climate. Moreover, the ecological niche modelling analysis showed that the southeastern (Chaquenean Province) and eastern Bolivia (Cerrado Province) are the most probable areas of occurrence of diploids and tetraploids, , respectively. The cytotype distribution observed support the hypothesis that the expansion of the geographic area associated with polyploidy played an important role in the evolutionary history of T. krapovickasii. [ABSTRACT FROM AUTHOR]

* Premise of the study: Information about geographic distribution of cytotypes can provide insight into the origin and maintenance of autopolyploid complexes and builds a foundation for understanding cytotype differentiation and the dynamics of mixed-ploidy populations. Here, we investigate environmental correlates of the geographic distributions of 6x and 9x individuals in the ecologically dominant grass Andropogon gerardii to examine the role of climate in shaping patterns of cytotype distribution in this species. * Methods: Flow cytometry was used to estimate ploidy level in 352 individuals from 32 populations across North America. Ecological differentiation of cytotypes was tested by relating BIOCLIM variables to cytotype distribution using principal components analysis and partial linear regression. * Key results: Broad geographic sampling confirmed two primary cytotypes--6x (hexaploid) and 9x (enneaploid)--and revealed that 9x plants are more common than previously thought. Enneaploids occur frequently in the southern portions of the range, with hexaploids dominating in northern regions. Mixed-ploidy populations were common (46.9%). Principal components analysis and partial linear regression indicated that reduced summer precipitation and increased variation in diurnal and seasonal temperature range were significant predictors of the frequency of 9x plants in a population. * Conclusions: Results indicate that (1) geographic distribution of 6x and 9x individuals is nonrandom; (2) environmental variables are associated with cytotype distribution in A. gerardii; and (3) nearly half of populations surveyed include both 6x and 9x individuals. The persistence of mixed-ploidy populations may reflect a combination of recurrent polyploid formation and the prevalence of clonal reproduction. [ABSTRACT FROM AUTHOR]

* Premise of the study: Polyploidy--the possession of more than two copies of each chromosome in the nucleus--is common in flowering plants. Polyploid plants can occupy different geographic ranges than their diploid progenitors, but the factors responsible for maintaining these range differences are poorly understood. Polyploidy can have significant physiological consequences, and the present study aims to determine whether previously described physiological differences between cytotypes are correlated with climatic niches and geographic distributions. * Methods: Prior research indicates that tetraploid plants of Chamerion angustifolium (Onagraceae) are more tolerant of drought and less tolerant of freezing than diploids, which suggests that they should occupy a niche that is warmer and drier than that of diploids. We extracted climate data for 134 populations of C. angustifolium classified as pure diploid, pure tetraploid, or mixed-ploidy. We compared climatic conditions between these population categories and generated ecological niche models to compare their geographic distribution with prior qualitative estimates. * Key results: Pure tetraploid populations occupy habitats that are warmer and drier than those of pure diploid populations. Mixed-ploidy populations occur in habitats that are not strictly intermediate between pure diploid and pure tetraploid populations, but are as cold as pure diploid populations and have intermediate soil moisture deficits. Our niche models were similar to previous qualitative estimates of cytotype geographic distribution. * Conclusions: The correspondence between the physiological tolerances of cytotypes, their climatic niches, and their geographic distributions suggests that physiological traits are at least partially responsible for differences in the realized climatic niches of diploid and tetraploid C. angustifolium. [ABSTRACT FROM AUTHOR]

Polyploidy is a common feature of agricultural weeds and natural area invaders. There are few studies comparing related diploid and polyploid exotics, however, and it is unclear what ecological and genetic factors favor the establishment of weedy polyploids. This research characterizes the geographic distribution and phenotypic characteristics of diploid Hedera helix and tetraploid Hedera hibernica, European species that are invading North American forests. To confirm the taxonomic affinity of invasive plants, we sequenced five non-coding cpDNA regions for 108 individuals (105 populations) as well as reference samples representing all species in the genus Hedera. Because diploid H. helix and tetraploid H. hibernica are poorly distinguished by morphology and DNA sequence, we used flow cytometry to determine their distribution (585 individuals). More than 90 % of sampled plants had cpDNA sequences identical or similar to H. helix sensu lato and H. hibernica. Diploid H. helix was dominant on the U.S. east coast (78.5 % of sampled plants) while tetraploid H. hibernica was dominant on the U.S. west coast (72.2 % of sampled plants), mirroring the species' occurrence in maritime versus continental climates of Europe. Moreover, for sympatric occurrences in the Pacific Northwest, H. hibernica was larger and more frequently reproductive than H. helix. In a 2-year garden experiment, tetraploid H. hibernica had substantial architectural differences compared to diploid H. helix, including larger (but less numerous) leaves and thicker (but less branched) stems. Field experiments are needed to evaluate 'pre-adaptation' (directional ecological filtering) and other factors mediating the invasion of H. helix and H. hibernica. [ABSTRACT FROM AUTHOR]

Due to its instantaneous effects on the genetics, phenotype, physiology and/or ecology of a plant, polyploidy can play an important role in facilitating plant invasions. Understanding the determinants of invasiveness in species with multiple ploidy levels requires a detailed knowledge of ploidy composition in native versus invaded ranges. Using DNA flow cytometry, we performed representative ploidy screening (277 localities, 333 individuals) across the native range of Oxalis pes- caprae and compared the data with those from invaded ranges. Both ranges showed striking differences in ploidy composition: whereas tetra- and especially pentaploids successfully colonized secondary areas, only di-, (very rare) tri- and tetraploids (dominant) were found in the native range of this species. Disregarding the diploid var. sericea, diploids and tetraploids of the nominate variety showed largely parapatric distribution in the native range, with a zone of overlap in the Northern Cape Province. Our results challenge the conventional scenario of the introduction of pentaploid individuals from the Greater Cape Floristic Region. The origin of the pentaploid cytotype is unclear and molecular tools applied in a large scale screening are needed to understand the invasion history of the species. [ABSTRACT FROM AUTHOR]

Background and Aims Genome duplication is widely acknowledged as a major force in the evolution of angiosperms, although the incidence of polyploidy in different floras may differ dramatically. The Greater Cape Floristic Region of southern Africa is one of the world's biodiversity hotspots and is considered depauperate in polyploids. To test this assumption, ploidy variation was assessed in a widespread member of the largest geophytic genus in the Cape flora: Oxalis obtusa. Methods DNA flow cytometry complemented by confirmatory chromosome counts was used to determine ploidy levels in 355 populations of O. obtusa (1014 individuals) across its entire distribution range. Ecological differentiation among cytotypes was tested by comparing sets of vegetation and climatic variables extracted for each locality. Key Results Three majority (2x, 4x, 6x) and three minority (3x, 5x, 8x) cytotypes were detected in situ, in addition to a heptaploid individual originating from a botanical garden. While single-cytotype populations predominate, 12 mixed-ploidy populations were also found. The overall pattern of ploidy level distribution is quite complex, but some ecological segregation was observed. Hexaploids are the most common cytotype and prevail in the Fynbos biome. In contrast, tetraploids dominate in the Succulent Karoo biome. Precipitation parameters were identified as the most important climatic variables associated with cytotype distribution. Conclusions Although it would be premature to make generalizations regarding the role of genome duplication in the genesis of hyperdiversity of the Cape flora, the substantial and unexpected ploidy diversity in Oxalis obtusa is unparalleled in comparison with any other cytologically known native Cape plant species. The results suggest that ploidy variation in the Greater Cape Floristic Region may be much greater than currently assumed, which, given the documented role of polyploidy in speciation, has direct implications for radiation hypotheses in this biodiversity hotspot. [ABSTRACT FROM PUBLISHER]

Background and Aims Investigating intraspecific karyotypic and genetic variations jointly can provide unique insights into how historical, ecological and cytogenetic factors influence microevolution. A coastal herb, Lysimachia mauritiana, exhibits extensive karyotypic polymorphism and displays a complex cytogeographic pattern across the Ryukyus. To explore whether a similar degree of chromosomal variation exists south of the Ryukyus, and in an attempt to ascertain the mechanisms that may have generated the patterns, comprehensive sampling was conducted in Taiwan. Methods Karyotypes were analysed at mitotic metaphase for 550 individuals from 42 populations throughout Taiwan Proper and its adjacent islands. In addition, genetic variation was estimated using 12 allozymes (21 loci) of 314 individuals sampled from 12 localities. Key Results Four chromosome numbers and eight cytotypes, including four endemic cytotypes, were detected. Cytotype distributions were highly structured geographically, with single cytotypes present in most populations and four major cytotypes dominating the north, east and south of Taiwan and the Penghu Archipelago. Allozyme variation was very low and F-statistics indicated an extremely high level of population differentiation, implying limited gene flow among populations. Cluster analysis of allozyme variation uncovered four geographic groups, each corresponding perfectly to the four dominant cytotypes. The geographic structure of cytotype distribution and allozyme variation probably resulted from severe genetic drift triggered by genetic bottlenecks, suggesting that Taiwanese populations were likely to be derived from four independent founder events. In the few localities with multiple cytotypes, cytogeographic patterns and inferences of chromosomal evolution revealed a trend of northward dispersal, consistent with the course of the Kuroshio Current that has been influential in shaping the coastal biota of the region. Conclusions The data elucidate the patterns of colonization and the effects of the Kuroshio Current on the distribution of L. mauritiana in Taiwan. These inferences are highly relevant to other coastal plant species in the region and will stimulate further studies. [ABSTRACT FROM AUTHOR]

Background and Aims Genome duplication is a central process in plant evolution and contributes to patterns of variation in genome size within and among lineages. Studies that combine cytogeography with genome size measurements contribute to our basic knowledge of cytotype distributions and their associations with variation in genome size. Methods Ploidy and genome size were assessed with direct chromosome counts and flow cytometry for 78 populations within the Claytonia perfoliata complex, comprised of three diploid taxa with numerous polyploids that range to the decaploid level. The relationship between genome size and temperature and precipitation was investigated within and across cytotypes to test for associations between environmental factors and nuclear DNA content. Key Results A euploid series (n = 6) of diploids to octoploids was documented through chromosome counts, and decaploids were suggested by flow cytometry. Increased variation in genome size among populations was found at higher ploidy levels, potentially associated with differential contributions of diploid parental genomes, variation in rates of genomic loss or gain, or undetected hybridization. Several accessions were detected with atypical genome sizes, including a diploid population of C. parviflora ssp. grandiflora with an 18 % smaller genome than typical, and hexaploids of C. perfoliata and C. parviflora with genomes 30 % larger than typical. There was a slight but significant association of larger genome sizes with colder winter temperature across the C. perfoliata complex as a whole, and a strong association between lower winter temperatures and large genome size for tetraploid C. parviflora. Conclusions The C. perfoliata complex is characterized by polyploids ranging from tetraploid to decaploid, with large magnitude variation in genome size at higher ploidy levels, associated in part with environmental variation in temperature. [ABSTRACT FROM AUTHOR]

We compared chromosome number (CN) variation among vascular floras of three different countries with increasing latitude in the Boreal hemisphere: Italy, Slovakia, Poland. Aim of the study was to verify whether the patterns of CN variation parallel the differences in latitudinal ranges. The three datasets comprised 3426 (Italy), 3493 (Slovakia) and 1870 (Poland) distinct cytotypes. Standard statistics (ANOVA, Kruskal-Wallis tests) evidenced significant differences among the three countries, mean CN increasing together with latitude. On the contrary, an inverse relation (r = -1) was evidenced among the frequency of odd CNs and latitude. Our results show that the hypothesis of a polyploid increase proportional with distance from the Equator seems to be confirmed, when territories from the same hemisphere are compared. [ABSTRACT FROM AUTHOR]

Background and Aims Patterns of ploidy variation among and within populations can provide valuable insights into the evolutionary mechanisms shaping the dynamics of plant systems showing ploidy diversity. Whereas data on majority ploidies are, by definition, often sufficiently extensive, much less is known about the incidence and evolutionary role of minority cytotypes. Methods Ploidy and proportions of endoreplicated genome were determined using DAPI (4',6-diamidino-2-phenylindole) flow cytometry in 6150 Gymnadenia plants (fragrant orchids) collected from 141 populations in 17 European countries. All widely recognized European species, and several taxa of less certain taxonomic status were sampled within Gymnadenia conopsea sensu lato. Key Results Most Gymnadenia populations were taxonomically and/or ploidy heterogeneous. Two majority (2x and 4x) and three minority (3x, 5x and 6x) cytotypes were identified. Evolution largely proceeded at the diploid level, whereas tetraploids were much more geographically and taxonomically restricted. Although minority ploidies constituted <2 % of the individuals sampled, they were found in 35 % of populations across the entire area investigated. The amount of nuclear DNA, together with the level of progressively partial endoreplication, separated all Gymnadenia species currently widely recognized in Europe. Conclusions Despite their low frequency, minority cytotypes substantially increase intraspecific and intrapopulation ploidy diversity estimates for fragrant orchids. The cytogenetic structure of Gymnadenia populations is remarkably dynamic and shaped by multiple evolutionary mechanisms, including both the ongoing production of unreduced gametes and heteroploid hybridization. Overall, it is likely that the level of ploidy heterogeneity experienced by most plant species/populations is currently underestimated; intensive sampling is necessary to obtain a holistic picture. [ABSTRACT FROM AUTHOR]

Polyploidy is an important evolutionary mechanism in plants, and in some genera (e.g., Solidago in Asteraceae) it is particularly widespread and is hypothesized to have played a major role in diversification. Goldenrods are notorious for their ploidy variation, with roughly 14% and 32% of recognized North American species being polyploid or including multiple cytotypes, respectively. We used traditional chromosome counts and flow cytometry to examine cytogeographic patterns, biogeographic and evolutionary hypotheses, and species boundaries in S. subsect. Humiles. Chromosome numbers and DNA ploidy determinations are reported for 337 individuals, including 148 new reports. Cytotypes show significant geographic structuring. Solidago simplex and S. spathulata were uniformly diploid (2n = 18) in western North America, while cytogeographic patterns in eastern North America were regionally complex and included 2n, 4n, and 6n cytotypes. Cytotypes within S. simplex were ecogeographically segregated and mixed-ploidy populations were rare. Data from this study and additional biosystematic data indicate that cytotypes in S. simplex fulfill the requirements of multiple species concepts and should best be treated as distinct species. Polyploid cytotypes possibly formed recurrently, however, and evolution and species boundaries within poly ploid S. simplex will require additional study. Results from this study and accumulated data from other studies suggest that biological species diversity in Solidago is considerably higher than currently recognized taxonomically. [ABSTRACT FROM AUTHOR]

Cytogeographical variability among 564 plants from 26 populations of Turnera sidoides subsp. pinnatifida in mountain ranges of central Argentina was analysed with meiotic chromosome counts and flow cytometry and is described at regional and local scales. Populations were primarily tetraploids (2 n = 4 x = 28), although diploid (2 n = 2 x = 14), hexaploid (2 n = 2 x = 42), and mixed populations of diploids and triploids (2 n = 3 x = 21) were also found. Diploids, triploids, and hexaploids were fewer in number and restricted to narrow areas, while tetraploids were the most common and geographically widespread cytotype. Diploids grew at higher altitudes and in colder and wet locations; tetraploids had the broadest ecological spectrum, while hexaploids occurred at the lowest altitudes and in drier conditions. The cytotypes were also spatially segregated at a microgeographical scale. Diploids grew in the piedmont, tetraploids were in the adjacent valley, and in the contact zone of both cytotypes, patches of diploids and triploids were found. At a regional scale, the distribution of the cytotypes may be governed by a combination of ecological and historical variables, while segregation in the contact zone may be independent of the selective environment because the cytotypes are unable to coexist as a result of reproductive exclusion. The role of triploids is also discussed. [ABSTRACT FROM AUTHOR]

The Actinidia chinensis complex, a group of commercially important fruits (kiwifruit), is a complex of functionally dioecious lianas of variable ploidy. To understand the cytogeography better and to facilitate breeding in this complex, we examined the ploidy and morphological variations in 16 natural populations of A. chinensis var. chinensis and A. chinensis var. deliciosa across an ecogeographical gradient. Four ploidy levels were found, var. chinensis consisting of diploids and tetraploids and var. deliciosa consisting of tetraploids, pentaploids and hexaploids. Hexaploids were centred in the western Yun-Gui plateau, tetraploids coexisted with hexaploids or diploids in the middle Yun-Gui plateau and the Wuling-Xuefeng mountains, and diploids occurred in the eastern Wuling-Xuefeng mountains and the Hunan foothills. These findings indicate a gradual, clinal transition from hexaploid to diploid across the elevational and longitudinal gradient. The clear geographical segregation of diploids and hexaploids may have arisen from their differential ecological adaptation in response to altitude and climate, whereas the coexistence of cytotypes (2 x-4 x, 4 x-6 x and 4 x-5 x-6 x) might be a result of reproductive barriers, with a particular contribution from the postzygotic reproductive isolation between ploidy races. The geographical pattern and morphological variation of cytotypes suggest a hybrid zone between the varieties in the Wuling-Xuefeng mountains. The differences in cytotypes which have arisen as a result of ecological adaptation, distribution and morphological characteristics will provide important baseline data for the selection of germplasm and the breeding of kiwifruit. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164, 72-83. [ABSTRACT FROM AUTHOR]