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-Variation in flower colour and pattern recorded at the Kleneč site. (A) Typical Dianthus arenarius subsp. bohemicus; (B) typical D. carthusianorum; (C) typical hybrid with an intermediate flower colour; (D) pale-flowered hybrid; (E) D. arenarius subsp. bohemicus with pink spots and hairs on the petal limb; (F) a single tuft of D. arenarius subsp. bohemicus with both white and light pink flowers. Note that (E) and (F) may be misidentified as hybrids and (D) erroneously identified as an endemic taxon.
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Hybridization between rare and common plant congeners can pose a serious threat to the rare species through gene swamping, production of hybrid seed at the expense of conspecific seed and/or hybrid competition for abiotic or biotic resources. Assessing the frequency and dynamics of interspecific hybridization is therefore of paramount importance fo...
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... of them had the same nuclear genome size as 4x D. arenarius subsp. bohemicus and intermediate C-values were only recorded for 11 individuals (~1.1% of all the samples analysed). Low intra-group variation and clear discontinuities in the amount of nuclear DNA between interspecific hybrids and their parents indicate that backcrossing is very unlikely. Interspecific hybrids may also originate via unreduced gametes of one or both parents (e.g. Koutecký et al. 2011). In our particular case, syngamy of an unreduced gamete of diploid D. carthusianorum and a reduced gamete of tetraploid D. arenarius subsp. bohemicus would yield tetraploid hybrids with a holoploid genome size only slightly different (by ~3% lower) from that of the tetraploid parent and therefore hard to distinguish with the aid of flow cytometry. However, we consider this hybrid scenario unlikely because all the tetraploid individuals with (partly) pink-coloured petals analysed grouped together with pure white plants of D. arenarius subsp. bohemicus in the PCA analysis, and were fertile. Moreover, both pure white and pink flowers can occur on the same plant ( Fig. 5F) and variation in petal colour is reported in several populations of other subspecies of D. arenarius (J. Vítová & P. Vít, unpubl. observations). Based on our experience, a pink tinge to the petals of D. arenarius often becomes more apparent as the flowers age. In addition, it seems that the production of unreduced gametes by D. carthu- sianorum is very low because our ploidy screening of samples from across central Europe revealed only one triploid (originating via a fusion of reduced and unreduced gametes) among the 732 plants analysed (unpubl. ...
Citations
... Similar results were reported in Plantago lanceolata and Lotus corniculatus, where hybrids of cultivated varieties showed higher germination rates than their wild relatives (Schröder & Prasse, 2013a). In Dianthus ssp., interspecific hybrids were less fertile with high abortion of pollen grains and no seed production in F1 (Vítová, Vít, & Suda, 2015). Increased fitness of hybrids has been described as heterosis (Lippman & Zamir, 2007). ...
Spontaneous hybridization in ex situ conservation facilities could potentially contaminate endangered plant species destined for the reintroduction into the wild. Despite the general recognition of the importance of such danger, studies exploring the consequences of hybridization including subsequent performance of the hybrids in comparison to the original species are rare. The aim of the present study was to assess the potential consequences of hybridization between the endangered endemic serpentinophyte species, Minuartia smejkalii, and its congener allopatric species, M. caespitosa. We performed controlled inter-specific crosses and compared seed production, germination, growth, seed morphology and dispersal ability between M. smejkalii and the hybrids. Our results showed that M. smejkalii and M. caespitosa can hybridize and produce viable seeds. Number of seeds per capsule produced by M. smejkalii and the hybrids did not differ but germination rates were higher in the hybrids. In addition , hybrids produced a higher number of flowers than M. smejkalii in open sites and serpentine soils, indicating that the hybrids perform better in the extreme serpentine conditions than the original serpentine species. Our simulation results showed a higher dispersal potential in hybrids compared to M. smejkalii despite their higher terminal velocity. Our results provide evidence that hybrid individuals from ex situ collections might outcompete the endemic M. smejkalii in the wild, if they are introduced by mistake. Therefore, for conservation and reintroduction purposes, ex situ hybridization events should be considered as a potential threat and treated carefully. We recommend establishing an adequate management of potentially crossable species and cautiously selecting individuals to be used for restoration.
... It can lead to the blurring of species boundaries due to the massive erosion of the gene pool of one or both hybridizing species (Coyne & Orr, 2004;Bardy et al., 2011;Gompert, Mandeville & Buerkle, 2017). Such effects are usually considered harmful because they may cause extinction of the hybridizing species that is rarer through genetic and/ or demographic swamping (Levin, Francisco-Ortega & Jansen, 1996;Vít et al., 2014;Balao et al., 2015;Vítová, Vít & Suda, 2015;Arrigo et al., 2016;Wayne & Shaffer, 2016). On the other hand, hybridization may contribute directly to the completion of reproductive isolation between hybridizing species as a result of reinforcement (Servedio & Noor, 2003) or lead to the origin of new ecotypes or species (Mallet, 2007). ...
Ficaria is a taxonomically intriguing polyploid complex with high morphological variability. Both hybridization and polyploidization have been suggested as the main evolutionary forces behind the high morphological variability in this genus; however, detailed studies are lacking. In Central Europe, two Ficaria taxa (diploid F. calthifolia and tetraploid F. verna subsp. verna) occasionally co-occur in local sympatry, which might result in hybridization. We investigated sympatric populations of the two Ficaria taxa using flow cytometry, chromosome counts, AFLP analysis and plastid DNA sequencing;
we also performed experimental homoploid and heteroploid crosses to determine the frequency and direction of hybrid triploid formation, an alternative route of triploid origin (autopolyploidy) and the possibility of one-step neoallotetraploid origin. Sympatric populations were composed of three genetic clusters corresponding to diploid
F. calthifolia (2n = 16), tetraploid F. verna subsp. verna (2n = 32) and triploid plants (2n = 24). The holoploid genome size and AFLP data suggest a hybrid origin of the triploids, thereby making their formation via autopolyploidization in F. calthifolia unlikely. The
triploid populations are monoclonal and of independent origin. In contrast, the parental populations exhibit high genotypic diversity and frequent sexual reproduction, including those of predominantly asexual F. verna subsp. verna. Experimental crossing confirmed that both parental taxa produce fertile seeds via a sexual pathway, but not by apomixis, and that both serve as pollen acceptors in heteroploid crosses, which is a finding consistent with the plastid sequencing. However, hybridization is asymmetric, with maternal-excess crosses being significantly more successful. No signs of neoautotetraploidization or neoallotetraploidization were detected. In summary, recent gene flow between the studied Ficaria taxa is either limited or absent.
... Without the use of additional markers (e.g. genome size or ploidy level), it is often difficult to accurately identify hybrids and pure individuals based on morphology only ( Ruhsam et al., 2015;Vítová, Vít, & Suda, 2015), and this can result in the misled protection of hybrid populations (Kabátová, Vít, & Suda, 2014;Vít, Wolfová, Urfus, Tájek, & Suda, 2014). ...
Crop cultivation can lead to genetic swamping of indigenous species and thus pose a serious threat for biodiversity. The rare Eurasian tetraploid shrub Prunus fruticosa (ground cherry) is suspected of hybridizing with cultivated allochthonous tetraploid P. cerasus and autochthonous diploid P. avium. Three Prunus taxa (447 individuals of P. fruticosa, 43 of P. cerasus and 73 of P. avium) and their hybrids (198 individuals) were evaluated using analysis of absolute genome size/ploidy level and multivariate morphometrics. Flow cytometry revealed considerable differentiation in absolute genome size at the tetraploid level (average 2C of P. fruticosa = 1.30 pg, average 2C of P. cerasus = 1.42 pg, i.e. a 9.2% difference). The combination of methods used allowed us to ascertain the frequency of hybrids occurring under natural conditions in Central Europe. The morphological evaluation of leaves was based upon distance‐based morphometrics supplemented by elliptic Fourier analysis. The results provided substantial evidence for ongoing hybridization (hybrids occurred in 39.5% of P. fruticosa populations). We detected homoploid introgressive hybridization with alien P. cerasus at the tetraploid level. We also found previously overlooked but frequent triploid hybrids resulting from heteroploid hybridization with indigenous P. avium, which, however, probably represent only the F1 generation. Although both hybrids differ in ploidy, they cannot be distinguished using morphometrics. Hybrids are frequent and may endanger wild populations of genuine P. fruticosa via direct niche competition or, alternatively or in addition, via introgression at the homoploid level (i.e. genetic swamping). The cultivation of cherries thus substantially threatens the existence of genuine P. fruticosa.
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... Such inventory programs are very important for resource management and conservation planning. In the flora of SW Asia, Caryophyllaceae are abundant in various natural ecosystems, but the delimitation of taxa in the family is problematic with issues such as clinal trends in morphological traits blurring the borders between taxa, frequent hybridization in some genera (such as Dianthus L., see Vítová & al., 2015), and seemingly artificial taxonomic borders appearing at various ranks. Harbaugh & al. (2010) Heywood (1964), with Rabeler (1984) providing additional nomenclatural clarification. ...
Assigning correct names to taxa is a challenging goal in the taxonomy of many groups within the Caryophyllaceae. This
challenge is most serious in tribe Caryophylleae since the supposed genera seem to be highly artificial, and the available morphological
evidence cannot effectively be used for delimitation and exact determination of taxa. The main goal of the present study was to re-assess
the monophyly of the genera currently recognized in this tribe using molecular phylogenetic data. We used the sequences of nuclear
ribosomal internal transcribed spacer (ITS) and the chloroplast gene rps16 for 135 and 94 accessions, respectively, representing all 16
genera currently recognized in the tribe Caryophylleae, with a rich sampling of Gypsophila as one of the most heterogeneous groups
in the tribe. Phylogenetic trees were reconstructed using maximum parsimony and Bayesian inference methods. The results show
that most of the large genera of Caryophylleae are not monophyletic. As a result, we propose a new classification system matching
both molecular phylogenetic and morphological evidence. The main taxonomic conclusions include: (1) the description of three new
genera, (2) treating five small genera as synonyms, (3) resurrecting the genus Heterochroa with six species, and (4) proposing 23
new combinations plus 2 replacement names at the specific level. As a result, we recognize 14 genera in Caryophylleae. A diagnostic
key to all genera of Caryophylleae is provided.
... An important issue related to the association of horticulture with the spontaneous flora is the direct impact of planted taxa have on natural processes by hybridizing with wild native species (Krahulcová et al. 1996, Daehler & Carino 2001, Stace & Crawley 2015, Vítová et al. 2015 or competing for pollinators (Chittka & Schürkens 2001, Jakobsson et al. 2009, Morales & Traveset 2009). Thus, a robust and scientifically based assessment of the propagule pressure of ornamental plants and their species pools is an important first step towards understanding the role of ornamental plants, and horticulture in general, in plant invasions and their impact on biodiversity (Humair et al. 2014). ...
Ornamental plants constitute an important source of alien, and potentially invasive species, but also include a substantial part of native flora and consist of taxa that occur both in the wild and in cultivation; yet garden floras are largely ignored in ecological studies.We studied ornamental plants in the Czech Republic in order to provide detailed information, based on field sampling, on the diversity of taxa grown in cultivation in private gardens. Sampling was done in accessible public areas, private gardens and private areas in villages, town- And city neighbourhoods, garden allotments, cemeteries, areas of dispersed farmhouse settlements not accessible to the public, and in new urban sprawl. The data can be used to estimate the propagule pressure of individual taxa, measured in terms of the frequency with which they are planted in the gardens. To make the data comparable across sites, we adopted a two-level approach that resulted in producing a detailed list (including all the taxa recorded) and an aggregated list (merging closely related and similar taxa, which was necessary in order to assess the frequency of planting across sites). Each species on the detailed list was assigned an origin, status, life history and cultivation requirements. Comparing the field records with national checklists of both native and alien vascular plants we quantified particular components of the ornamental flora. The floristic inventories for 174 sites yielded 1842 taxa on the detailed list, consisting of 1642 species (standard binomials), 9 cultivars assigned to genera, 147 hybrids and hybridogenous taxa, and 44 taxa identified at higher than species level. Of these taxa 1417 (76.9%) were alien and 420 (22.8%) native. The ornamental flora consisted of not-escaping aliens, escaping aliens and cultivated natives. Of the recorded taxa, 841 (45.6%) occur both in cultivation and the wild. The aggregated list comprised 1514 taxa and resulted from merging 533 taxa from the detailed list into 205 taxa. Most alien ornamentals are native to Asia and Americas. The proportion of escaped and not-escaping aliens significantly differed from wild aliens in the spontaneous flora with underrepresentation of escaped, which originated from Australia, Africa and the Mediterranean area. Taxa from Africa and anecophytes were overrepresented and those from Australia, the Mediterranean and other parts of Europe underrepresented among not escaping aliens. The assessment of planting frequency revealed that 270 taxa were found at more than 25% of the sites, while 584 (40%) occurred at only one or two sites.Winter annuals and shrubs are most represented among the commonly planted aliens; the only native species with comparably high planting frequencies among the aliens, are Vinca minor, Hedera helix and Aquilegia vulgaris. Related to the invasion potential of ornamental garden flora we analysed the recorded taxa with respect to the transient/persistent character of their occurrence. The core (persistent) part of the flora comprised 599 taxa (32% of the total number of taxa) and the transient 240 (13%) taxa. The "grey zone" between the two included 1003 taxa (55%). The results reported here provide quantitative insights into the role of horticulture as a major pathway of plant invasions.
... An important issue related to the association of horticulture with the spontaneous flora is the direct impact of planted taxa have on natural processes by hybridizing with wild native species (Krahulcová et al. 1996, Daehler & Carino 2001, Stace & Crawley 2015, Vítová et al. 2015 or competing for pollinators (Chittka & Schürkens 2001, Jakobsson et al. 2009, Morales & Traveset 2009). Thus, a robust and scientifically based assessment of the propagule pressure of ornamental plants and their species pools is an important first step towards understanding the role of ornamental plants, and horticulture in general, in plant invasions and their impact on biodiversity (Humair et al. 2014). ...
P. (2016): Dark side of the fence: ornamental plants as a source of wild-growing flora in the Czech Republic. – Preslia 88: 163–184. Ornamental plants constitute an important source of alien, and potentially invasive species, but also include a substantial part of native flora and consist of taxa that occur both in the wild and in cultivation ; yet garden floras are largely ignored in ecological studies. We studied ornamental plants in the Czech Republic in order to provide detailed information, based on field sampling, on the diversity of taxa grown in cultivation in private gardens. Sampling was done in accessible public areas, private gardens and private areas in villages, town-and city neighbourhoods, garden allotments, cemeteries , areas of dispersed farmhouse settlements not accessible to the public, and in new urban sprawl. The data can be used to estimate the propagule pressure of individual taxa, measured in terms of the frequency with which they are planted in the gardens. To make the data comparable across sites, we adopted a two-level approach that resulted in producing a detailed list (including all the taxa recorded) and an aggregated list (merging closely related and similar taxa, which was necessary in order to assess the frequency of planting across sites). Each species on the detailed list was assigned an origin, status, life history and cultivation requirements. Comparing the field records with national checklists of both native and alien vascular plants we quantified particular components of the ornamental flora. The floristic inventories for 174 sites yielded 1842 taxa on the detailed list, consisting of 1642 species (standard binomials), 9 cultivars assigned to genera, 147 hybrids and hybridogenous taxa, and 44 taxa identified at higher than species level. Of these taxa 1417 (76.9%) were alien and 420 (22.8%) native. The ornamental flora consisted of not-escaping aliens, escaping aliens and cultivated natives. Of the recorded taxa, 841 (45.6%) occur both in cultivation and the wild. The aggregated list comprised 1514 taxa and resulted from merging 533 taxa from the detailed list into 205 taxa. Most alien ornamentals are native to Asia and Americas. The proportion of escaped and not-escaping aliens significantly differed from wild aliens in the spontaneous flora with underrepresentation of escaped, which originated from Australia, Africa and the Mediterra-nean area. Taxa from Africa and anecophytes were overrepresented and those from Australia, the Mediterranean and other parts of Europe underrepresented among not escaping aliens. The assessment of planting frequency revealed that 270 taxa were found at more than 25% of the sites, while Preslia 88: 163–184, 2016 163 584 (40%) occurred at only one or two sites. Winter annuals and shrubs are most represented among the commonly planted aliens; the only native species with comparably high planting frequencies among the aliens, are Vinca minor, Hedera helix and Aquilegia vulgaris. Related to the invasion potential of ornamental garden flora we analysed the recorded taxa with respect to the transient/per-sistent character of their occurrence. The core (persistent) part of the flora comprised 599 taxa (32% of the total number of taxa) and the transient 240 (13%) taxa. The " grey zone " between the two included 1003 taxa (55%). The results reported here provide quantitative insights into the role of horticulture as a major pathway of plant invasions. K e y w o r d s: cultivated plants, Czech Republic, invasion, naturalization, ornamental flora, transient flora, urban areas
Are first-generation (F 1 ) hybrids typically intermediate for all traits that differentiate their parents? Or are they similar to one parent for most traits, or even mismatched for divergent traits? Although the phenotype of otherwise viable and fertile hybrids determines their fate, little is known about the general patterns, predictors, and consequences of phenotype expression in hybrids. To address this empirical gap, we compiled data from nearly 200 studies where traits were measured in a common environment for two parent populations and their F 1 hybrids. We find that individual traits are typically halfway between the parental midpoint and one parental value (i.e., hybrid trait values are typically 0.25 or 0.75 if parents' values are 0 & 1). When considering pairs of traits together, a hybrid's multivariate phenotype tends to resemble one parent (pairwise parent-bias) about 50 % more than the other while also exhibiting a similar magnitude of trait mismatch due to different traits having dominance in conflicting directions. We detect no phylogenetic signal nor an effect of parental genetic distance on dominance or mismatch. Using data from an experimental field planting of recombinant hybrid sunflowers---where there is among-individual variation in dominance and mismatch due to segregation of divergent alleles---we illustrate that pairwise parent-bias improves fitness while mismatch reduces fitness. Importantly, the effect of mismatch on fitness was stronger than that of pairwise parent-bias. In sum, our study has three major conclusions. First, hybrids between ecologically divergent natural populations are not phenotypically intermediate but rather exhibit substantial mismatch while also resembling one parent more than the other. Second, dominance and mismatch are likely determined by population-specific processes rather than general rules. Finally, selection against hybrids likely results from both selection against somewhat intermediate phenotypes and against mismatched trait combinations.
An overview of the diversity of vascular plants in the Czech Republic is presented. This country is situated at the intersection of several assumed important European migration routes. Consequently, the flora is composed of almost all the floristic elements that occur in Central Europe, of which the Central European geoelement is dominant. The occurrence of various sorts of relicts is discussed in the context of the changes in vegetation caused by Pleistocene climatic fluctuations. An account of Czech endemics includes 82 species and subspecies, which is 2.2% of the total vascular plant diversity in this country. Patterns in the distribution and occurrence of endemics in different habitat types are described. Groups of species with similar ecogeographical features within the Czech Republic are distinguished as regional types of distribution. Phytogeographical division of the country is described and the phytogeographical units distinguished are shown on a map.
Tremendous interspecific genome size variation is a well known phenomenon, whereas genome size within a species is supposed to be exceptionally stable and thus useful as a taxonomic trait. Using DAPI flow cytometry, we tested the stability of genome size in various representatives of Chenopodium s.s. (Amaranthaceae) across a broad geographical range (from Portugal to eastern Russia) in Eurasia. We sampled 1977 Chenopodium individuals of four different ploidies (di-, tetra-, hexa- and decaploids) from 347 populations. Intraspecific relative genome size variation was low, ranging from 2.0% in C. probstii to 7.7% in C. album, even in the species with broad distributions. We distinguished 12 homogeneous relative genome size groups among the 17 Chenopodium spp. tested. Genome size is useful for distinguishing certain morphologically similar groups of species such as C. suecicum/C. album, C. vulvaria/C. pamiricum–C. iljinii/C. sosnowskyi/C. karoi. Due to its genome size stability, the cosmopolitan species C. album can be used as an alternative internal standard in flow-cytometric analyses with the additional advantages of annual life cycle, self-compatibility and common occurrence all over the world. Finally, we did not detect any sign of hybridization between Chenopodium spp. of different ploidies.
