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.

Department of Botany Faculty of Science Charles University Prague Czech Republic

Faculty of Environmental Sciences Czech University of Life Sciences Prague Czech Republic

Institute of Botany The Czech Academy of Sciences Průhonice Czech Republic

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Aerts, R. , Berecha, G. , Gijbels, P. , Hundera, K. , Glabeke, S. , Vandepitte, K. , … Honnay, O. (2013). Genetic variation and risks of introgression in the wild PubMed DOI PMC

Anderson, E. C. , & Thompson, E. A. (2002). A model‐based method for identifying species hybrids using multilocus genetic data. Genetics, 160, 1217–1229. PubMed PMC

Arrigo, N. , Guadagnuolo, R. , Lappe, S. , Pasche, S. , Parisod, C. , & Felber, F. (2011). Gene flow between wheat and wild relatives: Empirical evidence from PubMed DOI PMC

Baird, W. V. , Estager, A. S. , & Wells, J. K. (1994). Estimating nuclear DNA content in peach and related diploid species using laser flow cytometry and DNA hybridization. Journal of the American Society for Horticultural Science, 119, 1312–1316.

Barać, G. , Ognjanov, V. , Vidaković, D. O. , Dorić, D. , Ljubojević, M. , Dulić, J. , … Gašić, K. (2017). Genetic diversity and population structure of European ground cherry (

Beghe, D. , Piotti, A. , Satovic, Z. , de la Rosa, R. , & Belaj, A. (2017). Pollen‐mediated gene flow and fine‐scale spatial genetic structure in PubMed PMC

Bennett, M. D. , & Leitch, I. J. (1995). Nuclear DNA amounts in angiosperms. Annals of Botany, 76, 113–176. 10.1006/anbo.1995.1085 DOI

Bennetzen, J. L. , Ma, J. , & Devos, K. M. (2005). Mechanisms of recent genome size variation in flowering plants. Annals of Botany, 95, 127–132. 10.1093/aob/mci008 PubMed DOI PMC

Boratyński, A. , Lewandowska, A. , & Ratyńska, H. (2003).

Burgess, K. S. , Morgan, M. , Deverno, L. , & Husband, B. C. (2005). Asymmetrical introgression between two PubMed DOI

Čertner, M. , Kolář, F. , Schönswetter, P. , & Frajman, B. (2015). Does hybridization with a widespread congener threaten the long‐term persistence of the Eastern Alpine rare local endemic PubMed DOI PMC

Chrtek, J. (1992).

Chudíková, R. , Ďurišová, Ľ. , Baranec, T. , & Eliáš, P. (2012). The reproductive biology of selected taxa of the genus

Coart, E. , van Glabeke, S. , de Loose, M. , Larsen, A. S. , & Roldán‐Ruiz, I. (2006). Chloroplast diversity in the genus PubMed DOI

Coart, E. , Vekemans, X. , Smulders, M. J. M. , Wagner, I. , van Huylenbroeck, J. , van Bockstaele, E. , & Roldán‐Ruiz, I. (2003). Genetic variation in the endangered wild apple ( PubMed DOI

Corlett, R. T. (2016). Plant diversity in a changing world: Status, trends, and conservation needs. Plant Diversity, 38, 10–16. 10.1016/j.pld.2016.01.001 PubMed DOI PMC

De Andrés, M. T. , Benito, A. , Pérez‐Rivera, G. , Ocete, R. , Lopez, M. A. , Gaforio, L. , … Arroyo‐García, R. (2012). Genetic diversity of wild grapevine populations in Spain and their genetic relationships with cultivated grapevines. Molecular Ecology, 21, 800–816. 10.1111/j.1365-294X.2011.05395.x PubMed DOI

Delplancke, M. , Alvarez, N. , Espíndola, A. , Joly, H. , Benoit, L. , Brouck, E. , & Arrigo, N. (2012). Gene flow among wild and domesticated almond species: Insights from chloroplast and nuclear markers. Evolutionary Applications, 5, 317–329. 10.1111/j.1752-4571.2011.00223.x PubMed DOI PMC

Dickson, E. E. , Arumuganathan, K. , Kresovich, S. , & Doyle, J. J. (1992). Nuclear DNA content variation within the Rosaceae. American Journal of Botany, 79, 1081–1086. 10.1002/j.1537-2197.1992.tb13697.x DOI

Doležel, J. , Greilhuber, J. , & Suda, J. (2007). Flow cytometry with plants: Analysis of genes, chromosomes and genomes. Weinheim: Wiley‐VCH; 10.1002/9783527610921 DOI

Dufresne, F. , Stift, M. , Vergilino, R. , & Mable, B. K. (2014). Recent progress and challenges in population genetics of polyploid organisms: An overview of current state‐of‐the‐art molecular and statistical tools. Molecular Ecology, 23, 40–69. 10.1111/mec.12581 PubMed DOI

Dzhangaliev, A. D. , Salova, T. N. , & Turekhanova, P. M. (2003). The wild fruit and nut plants of Kazakhstan. Horticultural Reviews, 29, 305–371.

Ellstrand, N. C. , & Elam, D. R. (1993). Population genetic consequences of small population size: Implications for plant conservation. Annual Review of Ecology and Systematics, 24, 217–242. 10.1146/annurev.es.24.110193.001245 DOI

Ellstrand, N. C. , Meirmans, P. , Rong, J. , Bartsch, D. , Ghosh, A. , de Jong, T. J. , … Hooftman, D. (2013). Introgression of crop alleles into wild or weedy populations. Annual Review of Ecology, Evolution, and Systematics, 44, 325–345. 10.1146/annurev-ecolsys-110512-135840 DOI

Ellstrand, N. C. , Prentice, H. C. , & Hancock, J. F. (1999). Gene flow and introgression from domesticated plants into their wild relatives. Annual Review of Ecology and Systematics, 30, 539–563. 10.1146/annurev.ecolsys.30.1.539 DOI

Frankham, R. , Ballou, J. D. , & Briscoe, D. A. (2010). Introduction to conservation genetics, 2nd ed Cambridge: Cambridge University Press; 10.1017/CBO9780511809002 DOI

Ganopoulos, I. V. , Aravanopoulos, F. A. , & Tsaftaris, A. (2013). Genetic differentiation and gene flow between wild and cultivated DOI

García‐Verdugo, C. , Calleja, J. A. , Vargas, P. , Silva, L. , Moreira, O. , & Pulido, F. (2013). Polyploidy and microsatellite variation in the relict tree PubMed DOI

Gross, B. L. , Henk, A. D. , Forsline, P. L. , Richards, C. M. , & Volk, G. M. (2012). Identification of interspecific hybrids among domesticated apple and its wild relatives. Tree Genetics & Genomes, 8, 1223–1235. 10.1007/s11295-012-0509-4 DOI

Hammer, Ø. , Harper, D. A. T. , & Ryan, P. D. (2001). Paleontological statistics software: Package for education and data analysis. Palaeontologia Electronica, 4(1), 1–9.

Hanušová, K. , Ekrt, L. , Vít, P. , Kolář, F. , & Urfus, T. (2014). Continuous morphological variation correlated with genome size indicates frequent introgressive hybridization among PubMed PMC

Hejda, M. , Pyšek, P. , & Jarošík, V. (2009). Impact of invasive plants on the species richness, diversity and composition of invaded communities. Journal of Ecology, 97, 393–403. 10.1111/j.1365-2745.2009.01480.x DOI

Horvath, A. , Zanetto, A. , Christmann, H. , Laigret, F. , & Tavaud, M. (2008). Origin of sour cherry ( DOI

Iezzoni, A. F. (2008). Cherries In Hancock J. F. (Ed.), Temperate fruit crop breeding: Germplasm to genomics (pp. 151–173). Dordrecht: Springer, Netherlands; 10.1007/978-1-4020-6907-9 DOI

Iezzoni, A. F. , & Mulinix, C. A. (1992). Variation in bloom time in a sour cherry germplasm collection. HortScience, 27, 1113–1114.

Iwata, H. , & Ukai, Y. (2002). SHAPE: A computer program package for quantitative evaluation of biological shapes based on elliptic Fourier descriptors. Journal of Heredity, 93, 384–385. 10.1093/jhered/93.5.384 PubMed DOI

Jäger, E. J. , & Seidel, D. (1995). Unterfamilie Prunoideae In Conert H. J., Jäger E. J., Kadereit J. W., Schultze‐Motel W., Wagenitz G., & Weber H. E. (Eds.), Gustav Hegi: Illustrierte Flora von Mitteleuropa, Vol. 4 (pp. 446–510).,

Kabátová, K. , Vít, P. , & Suda, J. (2014). Species boundaries and hybridization in central‐European

Kolář, F. , Čertner, M. , Suda, J. , Schönswetter, P. , & Husband, B. C. (2017). Mixed‐ploidy species: Progress and opportunities in polyploid research. Trends in Plant Science, 22, 1041–1055. PubMed

Kuhl, F. P. , & Giardina, C. R. (1982). Elliptic Fourier features of a closed contour. Computer Graphics and Image Processing, 18, 236–258. 10.1016/0146-664X(82)90034-X DOI

Lepší, P. , Lepší, M. , Boublík, K. , & Kolář, F. (2011). Reliktní a izolovaný výskyt

Lepší, M. , Vít, P. , Lepší, P. , Boublík, K. , & Kolář, F. (2009).

Lepší, M. , Vít, P. , Lepší, P. , Boublík, K. , & Suda, J. (2008).

Levin, D. A. , Francisco‐Ortega, J. , & Jansen, R. K. (1996). Hybridization and the extinction of rare plant species. Conservation Biology, 10, 10–16. 10.1046/j.1523-1739.1996.10010010.x DOI

Loureiro, J. , Trávníček, P. , Rauchová, J. , Urfus, T. , Vít, P. , Štech, M. , … Suda, J. (2010). The use of flow cytometry in the biosystematics, ecology and population biology of homoploid plants. Preslia, 82, 3–21.

Macková, L. , Vít, P. , Ďurišová, Ľ. , Eliáš, P. , & Urfus, T. (2017). Hybridization success is largely limited to homoploid DOI

Maghuly, F. , Schmoellerl, B. , Temsch, E. M. , & Laimer, M. (2010). Genome size, karyotyping and FISH physical mapping of 45S and 5S genes in two cherry rootstocks: PubMed DOI

Marhold, K. , & Wójcicki, J. J. (1992).

McVay, J. D. , Hipp, A. L. , & Manos, P. S. (2017). A genetic legacy of introgression confounds phylogeny and biogeography in oaks. Proceedings of the Royal Society B, 284, 20170300 10.1098/rspb.2017.0300 PubMed DOI PMC

Meusel, H. , Jäger, E. J. , & Weinert, E. (1965). Vergleichende Chorologie der zentraleuropaischen Flora, Vol. 1 Jena: VEB Gustav Fischer Verlag.

Michael, T. P. (2014). Plant genome size variation: Bloating and purging DNA. Briefings in Functional Genomics, 13, 308–317. 10.1093/bfgp/elu005 PubMed DOI

Oldén, E. J. , & Nybom, N. (1968). On the origin of

Petrov, D. A. (2001). Evolution of genome size: New approaches to an old problem. Trends in Genetics, 17, 23–28. 10.1016/S0168-9525(00)02157-0 PubMed DOI

Pruski, K. (2007). Tissue culture propagation of Mongolian cherry ( DOI

R Core Team (2017). R: A language and environment for statistical computing. Vienna: R Foundation for Statistical Computing; Retrieved from https://www.r-project.org/

Raudnitschka, D. , Hensen, I. , & Oberprieler, C. (2007). Introgressive hybridization of DOI

Rhodes, L. , & Maxted, N. (2016). Prunus fruticosa. In The IUCN Red List of Threatened Species 2016 (p. e.T172146A48415323). Retrieved from 10.2305/iucn.uk.2016-2.rlts.t172146a48415323.en DOI

Rhymer, J. M. , & Simberloff, D. (1996). Extinction by hybridization and introgression. Annual Review of Ecology and Systematics, 27, 83–109. 10.1146/annurev.ecolsys.27.1.83 DOI

Ruhsam, M. , Jacobs, T. , Watson, K. , & Hollingsworth, P. M. (2015). Is hybridisation a threat to DOI

Scholz, H. , & Scholz, I. (1995). Unterfamilie Prunoideae In Conert H. J., Jäger E. J., Kadereit J. W., Schultze‐Motel W., Wagenitz G., & Weber H. E. (Eds.), Gustav Hegi: Illustrierte Flora von Mitteleuropa, Vol. 4 (pp. 446–510).,

Schönswetter, P. , Suda, J. , Popp, M. , Weiss‐Schneeweiss, H. , & Brochmann, C. (2007). Circumpolar phylogeography of PubMed DOI

Schuster, M. , & Schreibner, H. (2000). Genome investigation in sour cherry, DOI

Šmarda, P. , & Bureš, P. (2006). Intraspecific DNA content variability in PubMed PMC

Šmarda, P. , & Bureš, P. (2010). Understanding intraspecific variation in genome size in plants. Preslia, 82, 41–61.

Soltis, P. S. , & Soltis, D. E. (2009). The role of hybridization in plant speciation. Annual Review of Plant Biology, 60, 561–588. 10.1146/annurev.arplant.043008.092039 PubMed DOI

Suda, J. , Krahulcová, A. , Trávníček, P. , Rosenbaumová, R. , Peckert, T. , & Krahulec, F. (2007). Genome size variation and species relationships in PubMed DOI PMC

Tavaud, M. , Zanetto, A. , David, J. L. , Laigret, F. , & Dirlewanger, E. (2004). Genetic relationships between diploid and allotetraploid cherry species ( PubMed DOI

Ter Braak, C. J. F. , & Šmilauer, P. (2012). CANOCO reference manual and user's guide: software for ordination (version 5.0). Ithaca: Microcomputer power.

Thórsson, Æ. T. , Pálsson, S. , Sigurgeirsson, A. , & Anamthawat‐Jónsson, K. (2007). Morphological variation among PubMed DOI PMC

Todesco, M. , Pascual, M. A. , Owens, G. L. , Ostevik, K. L. , Moyers, B. T. , Hübner, S. , … Rieseberg, L. H. (2016). Hybridization and extinction. Evolutionary Applications, 9, 892–908. 10.1111/eva.12367 PubMed DOI PMC

Van den Wollenberg, A. L. (1977). Redundancy analysis an alternative for canonical correlation analysis. Psychometrika, 42, 207–219. 10.1007/BF02294050 DOI

Vít, P. , Wolfová, K. , Urfus, T. , Tájek, P. , & Suda, J. (2014). Interspecific hybridization between rare and common plant congeners inferred from genome size data: Assessing the threat to the Czech serpentine endemic

Vítová, J. , Vít, P. , & Suda, J. (2015). Rare occurrence of reciprocal hybridization in a sympatric population of the Czech stenoendemic

Webb, D. A. (1968).

Wójcicki, J. J. (1988). Zmienność Prunus fruticosa Pallas w Polsce na tle zmienności gatunku [Variability of Prunus fruticosa Pallas]. Unpublished doctoral dissertation thesis, Polish Academy of Sciences, Krakow: Institute of Botany.

Wójcicki, J. J. (1991). Variability of Prunus fruticosa Pall. and the problem of an anthropohybridization. Veröffentlichungen Geobotanischen Institutes der ETH, Stiftung Rübel, Zürich, 106, 266‐272.

Wójcicki, J. J. , & Marhold, K. (1993). Variability, hybridization and distribution of

Morphological and environmental differentiation as prezygotic reproductive barriers between parapatric and allopatric Campanula rotundifolia agg. cytotypes

See more in PubMed

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