title: Genetic diversity and distribution patterns of diploid and polyploid hybrid water frog populations (Pelophylax esculentus complex) across Europe.
abstract: Polyploidization is a rare yet sometimes successful way for animals to rapidly create geno- and phenotypes that may colonize new habitats and quickly adapt to environmental changes. In this study, we use water frogs of the Pelophylax esculentus complex, comprising two species (Pelophylax lessonae, genotype LL; Pelophylax ridibundus, RR) and various diploid (LR) and triploid (LLR, LRR) hybrid forms, summarized as P. esculentus, as a model for studying recent hybridization and polyploidization in the context of speciation. Specifically, we compared the geographic distribution and genetic diversity of diploid and triploid hybrids across Europe to understand their origin, maintenance and potential role in hybrid speciation. We found that different hybrid and parental genotypes are not evenly distributed across Europe. Rather, their genetic diversity is structured by latitude and longitude and the presence/absence of parental species but not of triploids. Highest genetic diversity was observed in central and eastern Europe, the lowest in the northwestern parts of Europe. This gradient can be explained by the decrease in genetic diversity during postglacial expansion from southeastern glacial refuge areas. Genealogical relationships calculated on the basis of microsatellite data clearly indicate that hybrids are of multiple origin and include a huge variety of parental genomes. Water frogs in mixed-ploidy populations without any parental species (i.e. all-hybrid populations) can be viewed as evolutionary units that may be on their way towards hybrid speciation. Maintenance of such all-hybrid populations requires a continuous exchange of genomes between diploids and triploids, but scenarios for alternative evolutionary trajectories are discussed.
authors: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland.
authors: Alexandra
authors: A
authors: Hoffmann
authors: Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, Berlin, 10115, Germany.
authors: Jörg
authors: J
authors: Plötner
authors: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland.
authors: Nicolas B M
authors: NB
authors: Pruvost
authors: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland.
authors: Ditte G
authors: DG
authors: Christiansen
authors: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland.
authors: Sandra
authors: S
authors: Röthlisberger
authors: Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, AS CR, v.v.i., Rumburská 89, Liběchov, 277 21, Czech Republic.|Department of Biology and Ecology, Faculty of Science, University of Ostrava, Chittussiho 10, Ostrava, 710 00, Czech Republic.
authors: Lukáš
authors: L
authors: Choleva
authors: Department of Zoology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska dolina B-1, Bratislava, SK-84215, Slovak Republic.
authors: Peter
authors: P
authors: Mikulíček
authors: Faculty of Natural Sciences and Agricultural Sciences, University Ovidius Constanţa, Al. Universităţii 1, corp B, Constanţa, Romania.
authors: Dan
authors: D
authors: Cogălniceanu
authors: Department of Biology, Faculty of Sciences, University of Oradea, Universitatii str. 1, Oradea, 410087, Romania.
authors: István
authors: I
authors: Sas-Kovács
authors: Karazin Kharkiv National University, Svobody sq 4, Kharkiv, 62077, Ukraine.
authors: Dmitry
authors: D
authors: Shabanov
authors: Department of Evolutionary Genetic Basics of Systematics, Schmalhausen Institute of Zoology, B. Khmelnitskogo st., 15 Kyiv-30, Kyiv, MSP UA-01601, Ukraine.
authors: Svyatoslav
authors: S
authors: Morozov-Leonov
authors: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland.
authors: Heinz-Ulrich
authors: HU
authors: Reyer
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D004272:DNA, Mitochondrial / Q000235:genetics; D004171:Diploidy; D005060:Europe; D019143:Evolution, Molecular; D049810:Genetic Speciation; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D011123:Polyploidy; D011898:Ranidae / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial
keywords: Pelophylax; all-hybrid populations; founder effects; geographic distribution; hybrid speciation; microsatellites; mtDNA