Format: ORAL

Sara Palacio1,2*, Juan Pablo Ortiz-Brunel 3, Pablo Tejero 1,4, Michael J. Moore 5, Francisco Prez-Garca 6, M. Hilda Flores 7, Helga Ochoterena 7, Juan F. Mota 6, Sofa Bueno 1, Latif Kurt 8, Georgy A. Lazkov 9, Mike N. Lyons 10, Ebru Ozdeniz 8, Alexander V. Pavlenko 11, Anibal Prina 12, Kamal Shaltout 13, Khabibullo F. Shomurodov 14, Bekhruz Khabibullaev 14, Kobil Bobokalonov 15, Mariyo Boboev 16, Stefan Siebert 2, Matts Thulin 17, Hossein Akhani 18, Andreu Cera 1, 19, Georgia Chrysostomou 20, Adrin Escudero 21, Fabin Martnez-Hernndez 3, Farshid Memariani 22, Antonio Mendoza-Fernndez 3, Encarna Merlo 3, Carmelo M. Musarella 23, Esteban Salmern-Snchez 3, Stephen A. Smith 24, Giovanni Spampinato 23, Ioannis Vogiatziakis 25, Alexander Rudov 26.

1 Instituto Pirenaico de Ecología (IPE-CSIC), Jaca, Huesca, Spain. 2 School of Biological Sciences, North West University, Potchefstroom, South Africa 3 Departamento de Botánica, Universidad de Guadalajara, Zapopan, Jalisco, Mexico; 4 Botanika Saila, Sociedad de Ciencias Aranzadi, Donostia – San Sebastian, Gipuzkoa, Spain. 5 Oberlin College of Arts and Sciences, Oberlin, Ohio, USA 6 Departamento de Biología y Geología, CEI·MAR and CECOUAL, Universidad de Almería, Almería, Spain. 7 Instituto de Biología de la UNAM, Coyoacán, Ciudad de México, CDMX, México. 8 Faculty of Biology, Ankara University, Tandogan, Ankara, Turkey. 9 Institute of Biology & Pedology of the National Academy of Sciences, Bishkek, Kyrgyzstan. 10 Conservation Science Centre, Department of Biodiversity, Conservations and Attractions, Government of Western Australia, Australia. 11 Serdar Branch of the Center for Prevention of Especially Dangerous Infectious Diseases, State Sanitary and Epidemiological Service, Ministry of Health and Medical Industry of Turkmenistan, Serdar, Turkmenistan. 12 Facultad de Agronomía, Universidad Nacional de La Pampa, Santa Rosa, La Pampa, Argentina. 13 Botany Department, Faculty of Science, Tanta University, Tanta, Gharbia, Egypt. 14 Laboratory Geobotany and plant ecology, Institute of Botany Academy Sciences Republic of Uzbekistan, Tashkent, Uzbekistan. 15Institute of Botany, Plant Physiology and Genetics, National Academy of Tajikistan, Dushanbe, Tajikistan; 16 Khatlon Scientific Center of the National Academy of Tajikistan, Kulob Botanic Garden, Kuljab, Tajikistan, 17 Systematic Biology, Dept. of Organismal Biology, EBC, Uppsala Univ., Uppsala, Sweden. 18 Halophytes and C4 Plants Research Laboratory, Department of Plant Sciences, School of Biology, College of Sciences, University of Tehran, Tehran, Iran. 19 UFR des Sciences, Université Caen-Normandie. 20 Department of Forests, Ministry of Agriculture, Rural Development and Environment, Nicosia, Cyprus. 21 Área de Biodiversidad y Conservación. Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, Móstoles, Madrid, Spain. 22 Department of Botany, Research Center for Plant Sciences, Ferdowsi University of Mashhad, Mashhad, Iran. 23 Department of Agriculture, Mediterranean University of Reggio Calabria, Reggio Calabria, Italia. 24 Faculty of Pure and Applied Sciences at the Open University of Cyprus, Nicosia, Cyprus. 25 Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA; 26 Yerevan Botanical Garden, Yerevan 0035, Armenia. *Correspondence: s.palacio@ipe.csic.es

Plant species that grow only on unusual soils represent a significant proportion of plant diversity worldwide. These unique endemic communities are comprised of resilient and sometimes bizarre plants that thrive on difficult soils that most plant species cannot tolerate. One of the most widespread, yet understudied substrate-endemic floras of the world is that of gypsum soils. Gypsum (CaSO42H2O) soils occur worldwide in arid and semiarid ecosystems, posing serious restrictions to plant life. Despite these limitations, gypsum soils host rich endemic floras that have evolved independently on five continents. Plant communities growing on gypsum represent an excellent opportunity to investigate soils as a driving force in plant evolution and ecology, offering key insights into such fundamental biological processes as adaptation, the formation of new species, and the factors controlling plant community composition. Here we present the first global assessment of an edaphic endemic flora, providing information on the diversity, functional traits and conservation status of plants restricted to gypsum soils worldwide. Over 1200 taxa are restricted to gypsum in the world. These taxa belong to 86 families grouped in 32 orders, ranging from recently diversified groups like Poales to ferns, indicating restriction to gypsum soils evolved separately in different lineages of the plants tree of life and occurs in very distantly related groups. Most species are small perennial woody plants and almost half of the taxa are local endemics, pointing at the rarity and potential vulnerability of gypsophilic floras worldwide. Notably, more than a third of the gypsum endemic taxa have been listed in conservation reports or red lists and one-fourth are under a certain degree of protection. Our study highlights the singularity of gypsum ecosystems globally and calls for urgent action to preserve these unique plant communities.