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

Central European Institute of Technology Masaryk University 625 00 Brno Czechia

Department of Botany Faculty of Science Charles University 128 01 Prague Czechia

Department of Experimental Biology Faculty of Science Masaryk University 625 00 Brno Czechia

Institute of Botany Plant Science and Biodiversity Centre Slovak Academy of Sciences 845 23 Bratislava Slovak Republic

Zobrazit více v PubMed

Abbott R, Albach D, Ansell S, Arntzen JW, Baird SJ, Bierne N, Boughman J, Brelsford A, Buerkle CA, Buggs R et al. 2013. Hybridization and speciation. Journal of Evolutionary Biology 26: 229–246.

Abbott R, Hegarty MJ, Hiscock SJ, Brennan AC. 2010. Homoploid hybrid speciation in action. Taxon 59: 1375–1386.

Abbott RJ. 2017. Plant speciation across environmental gradients and the occurrence and nature of hybrid zones. Journal of Systematics and Evolution 55: 238–258.

Abbott RJ, Brennan AC. 2014. Altitudinal gradients, plant hybrid zones and evolutionary novelty. Philosophical Transactions of the Royal Society, B: Biological Sciences 369: 20130346.

Abbott RJ, Lowe AJ. 2004. Origins, establishment and evolution of new polyploid species: Senecio cambrensis and S. eboracensis in the British Isles. Biological Journal of the Linnean Society 82: 467–474.

Abbott RJ, Rieseberg LH. 2021. Hybrid speciation. eLS 2: 1–12.

Adler D, Kelly ST, Elliot T, Adamson J. 2022. vioplot: violin plot. R package version 0.4.0. [WWW document] URL https://github.com/TomKellyGenetics/vioplot.

Ainouche ML, Baumel A, Salmon A. 2004. Spartina anglica Schreb.: a natural model system for analysing early evolutionary changes that affect allopolyploid genomes. Biological Journal of the Linnean Society 82: 475–484.

Ainouche ML, Baumel A, Salmon A, Yannic G. 2003. Hybridization, polyploidy and speciation in Spartina (Poaceae). New Phytologist 161: 165–172.

Ančev M, Yurukova‐Grancharova P, Ignatova P, Goranova V, Stoyanov S, Yankova‐Tsvetkova E, Neykov N. 2013. Cardamine × rhodopaea (Brassicaceae), a triploid hybrid from the West Rhodope Mts: morphology, distribution, relationships and origin. Phytologia Balcanica 19: 323–338.

Anderson E. 1948. Hybridization of the habitat. Evolution 2: 1–9.

Arnold M, Ballerini E, Brothers A. 2012. Hybrid fitness, adaptation and evolutionary diversification: lessons learned from Louisiana Irises. Heredity 108: 159–166.

Arnold ML. 1992. Natural hybridization as an evolutionary process. Annual Review of Ecology, Evolution, and Systematics 23: 237–261.

Bartolić P, Morgan EJ, Padilla‐García N, Kolář F. 2024. Ploidy as a leaky reproductive barrier: mechanisms, rates and evolutionary significance of interploidy gene flow. Annals of Botany 134: 537–550.

Bartolić P, Voltrová A, Macková L, Šrámková G, Šlenker M, Mandáková T, Padilla García N, Marhold K, Kolář F. 2025. Overcoming ploidy barriers: the role of triploid bridges in the genetic introgression of Cardamine amara. Molecular Ecology 34: e17702.

Bolker BM, Brooks ME, Clark CJ, Geange SW, Poulsen JR, Stevens MHH, White J‐SS. 2009. Generalized linear mixed models: a practical guide for ecology and evolution. Trends in Ecology & Evolution 24: 127–135.

Brooks ME, Kristensen K, Van Benthem KJ, Magnusson A, Berg CW, Nielsen A, Skaug HJ, Machler M, Bolker BM. 2017. glmmTMB balances speed and flexibility among packages for zero‐inflated generalized linear mixed modeling. The R Journal 9: 378–400.

Brown MR, Abbott RJ, Twyford AD. 2024. The emerging importance of cross‐ploidy hybridisation and introgression. Molecular Ecology 33: e17315.

Buerkle CA. 2005. Maximum‐likelihood estimation of a hybrid index based on molecular markers. Molecular Ecology Notes 5: 684–687.

Carlsen T, Bleeker W, Hurka H, Elven R, Brochmann C. 2009. Biogeography and phylogeny of Cardamine (Brassicaceae). Annals of the Missouri Botanical Garden 96: 215–236.

Chrtek J, Herben T, Rosenbaumová R, Münzbergová Z, Dočkalová Z, Zahradníček J, Krejčíková J, Trávníček P. 2017. Cytotype coexistence in the field cannot be explained by inter‐cytotype hybridization alone: linking experiments and computer simulations in the sexual species Pilosella echioides (Asteraceae). BMC Evolutionary Biology 17: 87.

Doležel J, Greilhuber J, Suda J, eds. 2007. Flow cytometry with plant cells. Weinheim, Germany: Willey‐VCH Verlag.

Doležel J, Sgorbati S, Lucretti S. 1992. Comparison of three DNA fluorochromes for flow cytometric estimation of nuclear DNA content in plants. Physiologia Plantarum 85: 625–631.

Durand EY, Patterson N, Reich D, Slatkin M. 2011. Testing for ancient admixture between closely related populations. Molecular Biology and Evolution 28: 2239–2252.

Edger PP, Soltis DE, Yoshioka S, Vallejo‐Marin M, Shimizu‐Inatsugi R, Shimizu KK, Salmon A, Hiscock S, Ainouche M, Soltis PS. 2025. Natural neopolyploids: a stimulus for novel research. New Phytologist 246: 78–93.

Gómez JM, González‐Megías A, Lorite J, Abdelaziz M, Perfectti F. 2015. The silent extinction: climate change and the potential hybridization‐mediated extinction of endemic high‐mountain plants. Biodiversity and Conservation 24: 1843–1857.

Gompert Z, Buerkle AC. 2010. introgress: a software package for mapping components of isolation in hybrids. Molecular Ecology Resources 10: 378–384.

Gompert Z, Buerkle AC. 2012. bgc: software for Bayesian estimation of genomic clines. Molecular Ecology Resources 12: 1168–1176.

Goulet BE, Roda F, Hopkins R. 2017. Hybridization in plants: old ideas, new techniques. Plant Physiology 173: 65–78.

Harrison, RG. 1993. Hybrids and hybrid zones: historical perspective. In: Harrison, RG (ed.). Hybrid zones and the evolutionary process. New York, NY, USA: Oxford University Press, 3–12.

Hartig F. 2022. DHARMa: residual diagnostics for hierarchical (multi‐level/mixed) regression models. R package version 0.4.5. [WWW document] URL https://github.com/florianhartig/DHARMa

Herben T, Trávníček P, Chrtek J. 2016. Reduced and unreduced gametes combine almost freely in a multiploidy system. Perspectives in Plant Ecology, Evolution and Systematics 18: 15–22.

Heslop‐Harrison JS, Pat Schwarzacher T, Liu Q. 2023. Polyploidy: its consequences and enabling role in plant diversification and evolution. Annals of Botany 131: 1–10.

Hlásny T, Trombik J, Dobor L, Barcza Z, Barka I. 2016. Future climate of the Carpathians: climate change hot‐spots and implications for ecosystems. Regional Environmental Change 16: 1495–1506.

Hojsgaard D, Greilhuber J, Pellino M, Paun O, Sharbel TF, Hörandl E. 2014. Emergence of apospory and bypass of meiosis via apomixis after sexual hybridisation and polyploidisation. New Phytologist 204: 1000–1012.

Hopkins R. 2013. Reinforcement in plants. New Phytologist 197: 1095–1103.

Hörandl E, Hojsgaard D, Caperta A, Conceição SIR, Róis AS, Dickinson T, Mandáková T, Windham MD, Appelhans MS, Mráz P et al. 2024. Apomixis in systematics, evolution and phylogenetics of angiosperms: current developments and prospects. Critical Reviews in Plant Sciences 2024: 1–43.

Huang K, Ritland K, Guo S, Shattuck M, Li B. 2014. A pairwise relatedness estimator for polyploids. Molecular Ecology Resources 14: 734–744.

Husband BC. 2004. The role of triploid hybrids in the evolutionary dynamics of mixed‐ploidy populations. Biological Journal of the Linnean Society 82: 537–546.

Husband BC, Sabara HA. 2004. Reproductive isolation between autotetraploids and their diploid progenitors in fireweed, Chamerion angustifolium (Onagraceae). New Phytologist 161: 703–713.

Huska D, Leitch IJ, Ferreira de Carvalho J, Leitch AR, Salmon A, Ainouche M, Kovarik A. 2016. Persistence, dispersal and genetic evolution of recently formed Spartina homoploid hybrids and allopolyploids in Southern England. Biological Invasions 18: 2137–2151.

Huson DH, Bryant D. 2006. Application of phylogenetic networks in evolutionary studies. Molecular Biology and Evolution 23: 254–267.

Jiggins CD, Mallet J. 2000. Bimodal hybrid zones and speciation. Trends in Ecology & Evolution 15: 250–255.

Jombart T. 2008. adegenet: a R package for the multivariate analysis of genetic markers. Bioinformatics 24: 1403–1405.

Jombart T, Ahmed I. 2011. adegenet 1.3‐1: new tools for the analysis of genome‐wide SNP data. Bioinformatics 27: 3070–3071.

Kantor A, Kučera J, Šlenker M, Breidy J, Dönmez AA, Marhold K, Slovák M, Svitok M, Zozomová‐Lihová J. 2023. Evolution of hygrophytic plant species in the Anatolia‐Caucasus region: Insights from phylogenomic analyses of Cardamine perennials. Annals of Botany 131: 585–600.

Kearns AM, Restani M, Szabo I, Schrøder‐Nielsen A, Kim JA, Richardson HM, Marzluff JM, Fleischer RC, Johnsen A, Omland KE. 2018. Genomic evidence of speciation reversal in ravens. Nature Communications 9: 906.

Köhler C, Scheid OM, Erilova A. 2010. The impact of the triploid block on the origin and evolution of polyploid plants. Trends in Genetics 26: 142–148.

Köhler C, Dziasek K, Del Toro‐De León G. 2021. Postzygotic reproductive isolation established in the endosperm: mechanisms, drivers and relevance. Philosophical Transactions of the Royal Society B 376: 20200118.

Konowalik K, Tomasello S, Urbaniak J. 2025. Genetic diversity and ecogeographical niche overlap among hybridising Ox‐Eye Daisies (Leucanthemum, Asteraceae) in the Carpathian Mountains: the impact of anthropogenic disturbances. Molecular Ecology 34: e17581.

Körner C. 2021. Alpine plant life. Functional plant ecology of high mountain ecosystems. Berlin, Heidelberg: Springer‐Verlag.

Kozlov AM, Darriba D, Flouri T, Morel B, Stamatakis A. 2019. RAxML‐NG: A fast, scalable and user‐friendly tool for maximum likelihood phylogenetic inference. Bioinformatics 35: 4453–4455.

Krásná I. 2008. Cytogeografie Cardamine amara v České republice a objasnění původu tetraploidních populací (Cytogeography of Cardamine amara in the Czech Republic and the origin of tetraploid populations). M.Sc. thesis, Charles University, Praha, Czech Republic.

Kreiner JM, Kron P, Husband BC. 2017a. Evolutionary dynamics of unreduced gametes. Trends in Genetics 33: 583–593.

Kreiner JM, Kron P, Husband BC. 2017b. Frequency and maintenance of unreduced gametes in natural plant populations: Associations with reproductive mode, life history and genome size. New Phytologist 214: 879–889.

Leaché AD, Banbury BL, Felsenstein J, De Oca AN, Stamatakis A. 2015. Short tree, long tree, right tree, wrong tree: New acquisition bias corrections for inferring SNP phylogenies. Systematic Biology 64: 1032–1047.

Lenth RV. 2024. emmeans: estimated marginal means, aka least‐squares means. R package version 1.10.2. doi: 10.32614/CRAN.package.emmeans.

Levin DA. 1975. Minority cytotype exclusion in local plant populations. Taxon 24: 35–43.

Lewis PO. 2001. A likelihood approach to estimating phylogeny from discrete morphological character data. Systematic Biology 50: 913–925.

Li H. 2013. Aligning sequence reads, clone sequences and assembly contigs with BWA‐MEM. arXiv. doi: 10.48550/arXiv.1303.3997.

Lihová J, Kučera J, Perný M, Marhold K. 2007. Hybridization between two polyploid Cardamine (Brassicaceae) species in north‐western Spain: discordance between morphological and genetic variation patterns. Annals of Botany 99: 1083–1096.

Lihová J, Marhold K. 2006. Phylogenetic and diversity patterns in Cardamine (Brassicaceae) – a genus with conspicuous polyploid and reticulate evolution. In: Sharma AK, Sharma A, eds. Plant genome: biodiversity and evolution, 1C: Phanerogams (Angiosperms – Dicotyledons). Enfield: Science Publishers, 149–186.

Lihová J, Shimizu KK, Marhold K. 2006. Allopolyploid origin of Cardamine asarifolia (Brassicaceae): incongruence between plastid and nuclear ribosomal DNA sequences solved by a single‐copy nuclear gene. Molecular Phylogenetics and Evolution 39: 759–786.

Lövkvist B. 1956. The Cardamine pratensis complex. Outline of its cytogenetics and taxonomy. Symb Bot Upsal 14: 1–131.

Mallet J. 2005. Hybridization as an invasion of the genome. Trends in Ecology & Evolution 20: 229–237.

Mandáková T, Kovařík A, Zozomová‐Lihová J, Shimizu‐Inatsugi R, Shimizu KK, Mummenhoff K, Marhold K, Lysak MA. 2013. The more the merrier: recent hybridization and polyploidy in Cardamine. Plant Cell 25: 3280–3295.

Mandáková T, Lysak MA. 2016. Chromosome preparation for cytogenetic analyses in Arabidopsis. Current Protocols in Plant Biology 1: 43–51.

Mandáková T, Marhold K, Lysak MA. 2014. The widespread crucifer species Cardamine flexuosa is an allotetraploid with a conserved subgenomic structure. New Phytologist 201: 982–992.

Mandáková T, Zozomová‐Lihová J, Kudoh H, Zhao Y, Lysak MA, Marhold K. 2019. The story of promiscuous crucifers: origin and genome evolution of an invasive species, Cardamine occulta (Brassicaceae), and its relatives. Annals of Botany 124: 209–220.

Marhold K. 1994. Chromosome numbers of the genus Cardamine L. (Cruciferae) in the Carpathians and in Pannonia. Phyton (Horn) 34: 19–34.

Marhold K, Ančev ME, Tan K. 1996. A new subspecies of Cardamine amara (Brassicaceae) from Bulgaria and Greece. Annales Botanici Fennici 33: 199–204.

Marhold K, Kempa M, Kučera J, Skokanová K, Smatanová J, Šingliarová B, Šlenker M, Zozomová‐Lihová J. 2021. Database of names, chromosome numbers, ploidy levels and genome sizes of the tribe Cardamineae. [WWW document] URL https://cardamine.sav.sk [accessed Mar 2025].

Marhold K, Lihová J, Perný M, Grupe R, Neuffer B. 2002. Natural hybridization in Cardamine (Brassicaceae) in the Pyrenees: evidence from morphological and molecular data. Botanical Journal of the Linnean Society 139: 275–294.

Marhold K, Šlenker M, Zozomová‐Lihová J. 2018. Polyploidy and hybridization in the Mediterranean and neighbouring areas towards the north: examples from the genus Cardamine (Brassicaceae). Biologica Serbica 40: 47–59.

Marinova E, Lazarova M, Ivanov D, Tonkov S. 2023. Holocene vegetation history of the Western Rhodope Mountains (South Bulgaria): the paleoecological record of peat bog Beliya Kanton. Acta Palaeobotanica 63: 87–99.

Mason AS, Pires JC. 2015. Unreduced gametes: meiotic mishap or evolutionary mechanism? Trends in Genetics 31: 5–10.

McKenna A, Hanna M, Banks E, Sivachenko A, Cibulskis K, Kernytsky A, Garimella K, Altshuler D, Gabriel S, Daly M et al. 2010. The genome analysis toolkit: a MapReduce framework for analyzing next‐generation DNA sequencing data. Genome Research 20: 1297–1303.

Meirmans PG. 2020. genodive version 3.0: Easy‐to‐use software for the analysis of genetic data of diploids and polyploids. Molecular Ecology Resources 20: 1126–1131.

Melichárková A, Šlenker M, Zozomová‐Lihová J, Skokanová K, Šingliarová B, Kačmárová T, Caboňová M, Kempa M, Šrámková G, Mandáková T et al. 2020. So closely related and yet so different: Strong contrasts between the evolutionary histories of species of the Cardamine pratensis polyploid complex in Central Europe. Frontiers in Plant Science 11: 588856.

Milne RI, Abbott RJ. 2008. Reproductive isolation among two interfertile Rhododendron species: low frequency of post‐F1 hybrid genotypes in alpine hybrid zones. Molecular Ecology 17: 1108–1121.

Morgan EJ, Čertner M, Lučanová M, Deniz U, Kubíková K, Venon A, Kovářík O, Lafon Placette C, Kolář F. 2021. Disentangling the components of triploid block and its fitness consequences in natural diploid–tetraploid contact zones of Arabidopsis arenosa. New Phytologist 232: 1449–1462.

Nei M. 1972. Genetic distance between populations. The American Naturalist 106: 283–292.

Nevado B, Harris SA, Beaumont MA, Hiscock SJ. 2020. Rapid homoploid hybrid speciation in British gardens: The origin of Oxford ragwort (Senecio squalidus). Molecular Ecology 29: 4221–4233.

Nieto Feliner G, Álvarez I, Fuertes‐Aguilar J, Heuertz M, Marques I, Moharrek F, Piñeiro R, Riina R, Rosselló JA, Soltis PS et al. 2017. Is homoploid hybrid speciation that rare? An empiricist's view. Heredity 118: 513–516.

Nyarko CA, Katche E, Báez M, Lv Z, Mason AS. 2025. A wide range of chromosome numbers result from unreduced gamete production in Brassica juncea × B. napus (AABC) interspecific hybrids. Heredity 134: 98–108.

Ortiz EM. 2019. vcf2phylip v2.0: convert a VCF matrix into several matrix formats for phylogenetic analysis. Zenodo. doi: 10.5281/zenodo.2540861.

Pembleton LW, Cogan NOI, Forster JW. 2013. StAMPP: an R package for calculation of genetic differentiation and structure of mixed‐ploidy level populations. Molecular Ecology Resources 13: 946–952.

Perný M, Tribsch A, Anchev ME. 2004. Differentiation in the Balkan diploid Cardamine acris (Brassicaceae): molecular and morphological evidence. Folia Geobotanica 39: 405–429.

Peterson BK, Weber JN, Kay EH, Fisher HS, Hoekstra HE. 2012. Double digest RADseq: An inexpensive method for de novo SNP discovery and genotyping in model and nonmodel species. PLoS ONE 7: e37135.

Peterson R, Slovin JP, Chen C. 2010. A simplified method for differential staining of aborted and non‐aborted pollen grains. International Journal of Plant Biology 1: e13.

Pritchard JK, Stephens M, Donnelly P. 2000. Inference of population structure using multilocus genotype data. Genetics 155: 945–959.

R Core Team. 2021. R: a language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing.

R Core Team. 2024. R: a language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing.

Ramsey J. 2007. Unreduced gametes and neopolyploids in natural populations of Achillea borealis (Asteraceae). Heredity 98: 143–150.

Ramsey J, Schemske DW. 1998. Pathways, mechanisms, and rates of polyploid formation in flowering plants. Annual Review of Ecology and Systematics 29: 467–501.

Rieseberg LH. 1997. Hybrid origins of plant species. Annual Review of Ecology, Evolution, and Systematics 28: 359–389.

Rieseberg LH, Kim SC, Randell RA, Whitney KD, Gross BL, Lexer C, Clay K. 2007. Hybridization and the colonization of novel habitats by annual sunflowers. Genetica 129: 149–165.

Robertson K, Goldberg EE, Igić B. 2011. Comparative evidence for the correlated evolution of polyploidy and self‐compatibility in Solanaceae. Evolution 65: 139–155.

Ru Y, Mandáková M, Lysak MA, Koch MA. 2022. The evolutionary history of Cardamine bulbifera shows a successful rapid postglacial Eurasian range expansion in the absence of sexual reproduction. Annals of Botany 130: 245–263.

Salisbury EJ. 1965. The reproduction of Cardamine pratensis L. and Cardamine palustris Peterman particularly in relation to their specialized foliar vivipary, and its deflexion of the constraints of natural selection. Proceedings of the Royal Society of London B: Biological Sciences 163: 321–342.

Šarhanová P, Majeský Ľ, Sochor M. 2024. A novel strategy to study apomixis, automixis, and autogamy in plants. Plant Reproduction 37: 379–392.

Seehausen O, Takimoto G, Roy D, Jokela J. 2008. Speciation reversal and biodiversity dynamics with hybridization in changing environments. Molecular Ecology 17: 30–44.

Shimizu KK, Tsuchimatsu T. 2015. Evolution of selfing: recurrent patterns in molecular adaptation. Annual Review of Ecology, Evolution, and Systematics 46: 593–622.

Šingliarová B, Hojsgaard D, Müller‐Schärer H, Mráz P. 2023. The novel expression of clonality following whole‐genome multiplication compensates for reduced fertility in natural autopolyploids. Proceedings of the Royal Society B: Biological Sciences 290: 20230389.

Šingliarová B, Zozomová‐Lihová J, Mráz P. 2019. Polytopic origin and scale‐dependent spatial segregation of cytotypes in primary diploid–autopolyploid contact zones of Pilosella rhodopea (Asteraceae). Biological Journal of the Linnean Society 126: 360–379.

Šlenker M. 2024. VCF_prune (1.1.0). Zenodo. doi: 10.5281/zenodo.10522817.

Šlenker M, Kantor A, Marhold K, Schmickl R, Mandáková T, Lysak MA, Perný M, Caboňová M, Slovák M, Zozomová‐Lihová J. 2021. Allele Sorting as a novel approach to resolving the origin of allotetraploids using Hyb‐Seq data: a case study of the Balkan mountain endemic Cardamine barbaraeoides. Frontiers in Plant Science 12: 659275.

Šlenker M, Kantor A, Senko D, Mártonfiová L, Šrámková G, Cetlová V, Dönmez A, Yüzbaşıoğlu S, Zozomová‐Lihová J. 2024. Genome‐wide data uncover cryptic diversity with multiple reticulation events in the Balkan‐Anatolian Cardamine (Brassicaceae) species complex. Molecular Ecology 33: e17564.

Šmíd J, Douda J, Krak K, Mandák B. 2020. Analyses of hybrid viability across a hybrid zone between two Alnus species using microsatellites and cpDNA markers. Genes 11: 770.

Soltis DE, Albert VA, Leebens‐Mack J, Bell CD, Paterson AH, Zheng C, Sankoff D, de Pamphilis CW, Wall PK, Soltis PS. 2009. Polyploidy and angiosperm diversification. American Journal of Botany 96: 336–348.

Soltis DE, Soltis PS, Pires JC, Kovarik A, Tate JA, Mavrodiev E. 2004a. Recent and recurrent polyploidy in Tragopogon (Asteraceae): cytogenetic, genomic and genetic comparisons. Biological Journal of the Linnean Society 82: 485–501.

Soltis DE, Soltis PS, Tate JA. 2004b. Advances in the study of polyploidy since Plant speciation. New Phytologist 161: 173–191.

Soltis PS, Plunkett GM, Novak SJ, Soltis DE. 1995. Genetic variation in Tragopogon species: additional origins of the allotetraploids T. mirus and T. miscellus (Compositae). American Journal of Botany 82: 1329–1341.

Soltis PS, Soltis DE. 2009. The role of hybridization in plant speciation. Annual Review of Plant Biology 60: 561–588.

Stebbins GL. 1959. The role of hybridization in evolution. Proceedings of the American Philosophical Society 103: 231–251.

Sun J, Shimizu‐Inatsugi R, Hofhuis H, Shimizu K, Hay A, Shimizu KK, Sese J. 2020. A recently formed triploid Cardamine insueta inherits leaf vivipary and submergence tolerance traits of parents. Frontiers in Genetics 11: 567262.

Symonds VV, Soltis PS, Soltis DE. 2010. Dynamics of polyploid formation in Tragopogon (Asteraceae): recurrent formation, gene flow, and population structure. Evolution 64: 1984–2003.

Tedder A, Helling M, Pannell JR, Shimizu‐Inatsugi R, Kawagoe T, van Campen J, Sese J, Shimizu KK. 2015. Female sterility associated with increased clonal propagation suggests a unique combination of androdioecy and asexual reproduction in populations of Cardamine amara (Brassicaceae). Annals of Botany 115: 763–776.

Todesco M, Pascual MA, Owens GL, Ostevik KL, Moyers BT, Hübner S, Heredia SM, Hahn MA, Caseys C, Bock DG et al. 2016. Hybridization and extinction. Evolutionary Applications 9: 892–908.

Tsujimoto M, Araki KS, Honjo MN, Yasugi M, Nagano AJ, Akama S, Hatakeyama M, Shimizu‐Inatsugi R, Sese J, Shimizu KK et al. 2020. Genet assignment and population structure analysis in a clonal forest‐floor herb, Cardamine leucantha, using RAD‐seq. AoB Plants 12: plz080.

Urbanska KM, Hurka H, Landolt E, Neuffer B, Mummenhoff K. 1997. Hybridization and evolution in Cardamine (Brassicaceae) at Urnerboden, central Switzerland: Biosystematic and molecular evidence. Plant Systematics and Evolution 204: 233–256.

Urbanska KM, Landolt E. 1999. Patterns and processes of man‐influenced hybridisation in Cardamine L. In: van Raamsdonk LWD, den Nijs HCM, eds. Plant evolution in man‐made habitats. Amsterdam, the Netherlands: Hugo de Vries Laboratory, 29–47.

Urbanska‐Worytkiewicz KM. 1977. Reproduction in natural triploid hybrids (2n = 24) between Cardamine rivularis Schur and C. amara L. Berichte des Geobotanischen Institutes Der Eidgenössischen Technischen Hochschule Stiftung Rübel 44: 42–85.

Vallejo‐Marín M, Cooley AM, Yuequi Lee M, Folmer M, McKain MR, Puzey JR. 2016. Strongly asymmetric hybridization barriers shape the origin of a new polyploid species and its hybrid ancestor. American Journal of Botany 103: 1272–1288.

Vallejo‐Marín M, Hiscock SJ. 2016. Hybridization and hybrid speciation under global change. New Phytologist 211: 1170–1187.

Vallejo‐Marín M, Lye GC. 2013. Hybridisation and genetic diversity in introduced Mimulus (Phrymaceae). Heredity 110: 111–122.

Vallejo‐Marín M, Quenu M, Ritchie S, Meeus S. 2017. Partial interfertility between independently originated populations of the neo‐allopolyploid Mimulus peregrinus. Plant Systematics and Evolution 303: 1081–1092.

Van de Peer Y, Mizrachi E, Marchal K. 2017. The evolutionary significance of polyploidy. Nature Reviews. Genetics 18: 411–424.

Welles SR, Ellstrand NC. 2016. Genetic structure reveals a history of multiple independent origins followed by admixture in the allopolyploid weed Salsola ryanii. Evolutionary Applications 9: 871–878.

Welles SR, Ellstrand NC. 2020. Evolution of increased vigour associated with allopolyploidization in the newly formed invasive species Salsola ryanii. AoB Plants 12: plz039.

Wolf D, Takebayashi N, Rieseberg LH. 2001. Predicting the risk of extinction through hybridization. Conservation Biology 15: 1039–1053.

Zozomová‐Lihová J, Krak K, Mandáková T, Shimizu KK, Španiel S, Vít P, Lysak MA. 2014. Multiple hybridization events in Cardamine (Brassicaceae) during the last 150 years: revisiting a textbook example of neoallopolyploidy. Annals of Botany 113: 817–830.

Zozomová‐Lihová J, Malánová‐Krásná I, Vít P, Urfus T, Senko D, Svitok M, Kempa M, Marhold K. 2015. Cytotype distribution patterns, ecological differentiation, and genetic structure in a diploid–tetraploid contact zone of Cardamine amara. American Journal of Botany 102: 1380–1395.