Genetic status of the endangered plant species Gladiolus palustris in the western part of its distribution area Laura Daco, Tiphaine Maurice, Serge Muller, Julie Rossa, Guy Colling To cite this version: Laura Daco, Tiphaine Maurice, Serge Muller, Julie Rossa, Guy Colling. Genetic status of the en- dangered plant species Gladiolus palustris in the western part of its distribution area. Conservation Genetics, Springer Verlag, 2019, 1 (6), pp.1339-1354. 10.1007/s10592-019-01213-0. hal-02344630 HAL Id: hal-02344630 https://hal.sorbonne-universite.fr/hal-02344630 Submitted on 4 Nov 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Conservation Genetics (2019) 20:1339–1354 https://doi.org/10.1007/s10592-019-01213-0 RESEARCH ARTICLE Genetic status of the endangered plant species Gladiolus palustris in the western part of its distribution area Laura Daco1,2,3 · Tiphaine Maurice1,4 · Serge Muller4,5 · Julie Rossa1,4 · Guy Colling1 Received: 21 November 2018 / Accepted: 9 August 2019 / Published online: 24 August 2019 © The Author(s) 2019 Abstract Many endangered plant species sufer from the efects of ongoing fragmentation of their populations leading to a loss of genetic diversity through genetic drift. In addition, populations of rare plants may also be afected by hybridization with other plant species. We studied the genetic population structure of populations of the endangered Gladiolus palustris in the western limit of its distribution area using AFLP markers. In addition, we clarifed the taxonomic status of populations where hybridization with the closely related G. imbricatus was suspected based on morphology by sequencing the ITS region of the nuclear ribosomal DNA as well as two regions of the chloroplast DNA. Our analysis of the genetic population structure of G. palustris revealed a strong diferentiation among geographical regions, which was much higher than the diferentiation among populations within regions. Most populations retained a considerable amount of genetic variation. To counteract the future loss of genetic diversity through drift, we recommend using the largest populations per region as seed source to increase genetic diversity in genetic depauperate populations of the same region. Our genetic analyses indicated that some French populations of G. palustris are of hybrid origin. These hybridization events are likely to be ancient as these popula- tions are very isolated and some parent taxa went regionally extinct. As these hybrid populations may elucidate post-glacial distribution patterns of related Gladiolus taxa, we advocate that they deserve the same conservation eforts as purebred ones. Keywords Conservation · Endangered · Genetic diversity · Gladiolus palustris · Plant species hybridization Introduction Many endangered plant species are considered to sufer from the efects of ongoing habitat destruction, which has often led to an increased isolation and fragmentation of their Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s1059 2-019-01213 -0) contains populations. As a consequence, populations of rare plants supplementary material, which is available to authorized users. often sufer from a loss of genetic diversity due to the loss of alleles through genetic drift (Young et al. 1996; Frankham * Laura Daco and Wilcken 2006; Yuan et al. 2012). Genetic diferentia- [email protected] tion among populations and the loss of genetic diversity is 1 Population Biology and Evolution, Musée national d’histoire expected to increase with time since fragmentation (Coates naturelle, 25 rue Münster, 2160 Luxembourg, Luxembourg 1988; Gitzendanner and Soltis 2000; Zawko et al. 2001). 2 Institut de Botanique, Université de Strasbourg, 28 rue In Europe, nutrient-poor wet grasslands belong to the most Goethe, 67000 Strasbourg, France threatened and fragmented habitat types (van Duren et al. 3 Fondation faune-fore, 24 rue Münster, 2160 Luxembourg, 1997; Bakker and Berendse 1999; Oelmann et al. 2009). Luxembourg Many of these grasslands have been drained and fertilized 4 Laboratoire Interdisciplinaire des Environnements to increase agricultural productivity or have been aban- Continentaux (LIEC), Université de Lorraine, CNRS, UMR doned. These changes in land use practices have led to the 7360, rue du Général Delestraint, 57070 Metz, France decline and genetic impoverishment of many plant species 5 Muséum national d’Histoire naturelle, UMR 7205 ISYEB, (Bakker and Berendse 1999; Vergeer et al. 2003; Wesche CNRS, UPMC, EPHE, Sorbonne Universités, CP 39, 16 rue et al. 2012). Among the plant species that have become rare Bufon, 75005 Paris, France Vol.:(0123456789)1 3 1340 Conservation Genetics (2019) 20:1339–1354 through the destruction and fragmentation of wet grasslands morphological analyses that G. palustris and G. imbri- is the sword-lily species Gladiolus palustris GAUDIN, a catus naturally hybridize to form the nothospecies G. × Western and Central European species which is declining sulistrovicus (Cieślak et al. 2014; Szczepaniak et al. 2016) all across Europe and is considered to be threatened in many in the eastern part of the distribution area of G. palus- countries (Bilz et al. 2011; UICN France et al. 2012). G. tris where the distributions of both taxa partially overlap. palustris is legally protected in the European Union (Annex Molecular data showed that in the case of G. × sulistro- II Habitats Directive 92/43/EEC) and in Switzerland. The vicus hybridization is unidirectional with G. palustris as closely related Gladiolus imbricatus L., considered to be the maternal species and G. imbricatus as the pollen donor less threatened, has a larger distribution area extending from (Szczepaniak et al. 2016). Central to Eastern Europe (Fig. 1). Morphological distinc- Although interspecifc hybridization is considered to tion of both taxa in the feld is difcult without examining be an important force of plant evolution (Soltis and Soltis the corm, which is often not possible for conservation rea- 2009), it also can have detrimental efects on endangered sons. At the western limit of its distribution area in France plant taxa through genetic swamping and hybrid backcross- Gladiolus palustris occurs in very isolated populations and ing with one of the parental taxa (Allendorf et al. 2001; some populations have been identifed morphologically as Todesco et al. 2016). The discrimination between cryptic G. imbricatus but their taxonomic status is unclear (Tison hybrids (Gaskin and Kazmer 2009) and purebred taxa has and Girod 2014). important implications for the delineation of conserva- Closely related congeneric taxa are likely to hybridize tion units (Allendorf et al. 2001). The clarifcation of the as they often have incomplete reproductive isolation (Mal- taxonomic status of populations of endangered species is let 2005, 2008; Soltis and Soltis 2009; Soltis 2013). When important for appropriate conservation measures (Smith and the ecological niches of closely related species are similar, Waterway 2008; Nierbauer et al. 2017). Although hybrid they may coexist at certain parts of their distribution area populations may have a certain conservation interest, protec- and hybridization can occur in these contact zones espe- tive laws often ignore hybrids. It has been argued that hybrid cially when both taxa have the same ploidy level (Chap- populations are not worth conserving because hybridization man and Abbott 2010) as it is the case for G. palustris events may be due to anthropogenic infuences such as the and G. imbricatus (2n = 4x = 60; Cantor and Tolety 2011). introduction of plants and animals, habitat fragmentation Hybridization and polyploidy strongly infuenced the evo- and habitat modifcation (Allendorf et al. 2001). The use of lution of European Gladiolus species (van Raamsdonk and molecular methods can help to clarify the taxonomic status de Vries 1989; Cantor and Tolety 2011; Tison and Girod of populations of closely related rare plant species (Tur- 2014). It has been recently confrmed by molecular and chetto et al. 2015; Segatto et al. 2017). Fig. 1 Distribution map and study sites of G. palustris and G. imbricatus across Central and Western Europe. For population names, see Table 1, regions are in between brackets. Gray circles represent G. palustris populations and black circles represent G. imbrica- tus populations. Taxonomic identifcation was based on morphology. Populations with evidence for hybridization based on genetic analyses are marked with asterisk. Map created with SimpleMappr modifed from Meusel et al. (1965) and Szczepaniak et al. (2016) 1 3 Conservation Genetics (2019) 20:1339–1354 1341 We studied the genetic population structure of the endan- (5 U/µl, Thermo Scientifc). Polymerase chain reaction was gered G. palustris in the western part of its distribution area performed with 20 cycles at 94 °C for 30 s, 56 °C for 1 min in France and Switzerland using AFLP markers to assess the and 72 °C for 1 min. The solution was then diluted with efects of habitat fragmentation.