title: Characterizing a hybrid zone between a cryptic species pair of freshwater snails.
abstract: Characterizing hybrid zones and their dynamics is a central goal in evolutionary biology, but this is particularly challenging for morphologically cryptic species. The lack of conspicuous divergence between parental types means intermediate hybrid forms often go undetected. We aimed to detect and characterize a suspected hybrid zone between a pair of morphologically cryptic lineages of the freshwater snail, Radix. We sampled Radix from across a contact zone between two mitochondrial lineages (Radix balthica and an undescribed lineage termed 'MOTU3') and detected admixture between two nuclear genotype clusters, which were significantly but not categorically associated with the mitochondrial lineages. Using a model selection approach, we show that the admixture cline is best explained by an interaction between precipitation and temperature gradients over the area, rather than geographic distance. We thus hypothesize that the correlation with climatic gradients suggests environmental selection has played a role in maintaining the hybrid zone. In a 2050 climate change scenario, we furthermore predict an expansion of one of the nuclear clusters and a widening of the hybrid zone as the climate warms and dries.
authors.affiliation: Biodiversity und Climate Research Centre by Senckenberg Naturforschende Gesellschaft and Goethe-Universität, 60325, Frankfurt, Germany.
authors.forename: Simit
authors.initials: S
authors.lastname: Patel
authors.forename: Tilman
authors.initials: T
authors.lastname: Schell
authors.forename: Constanze
authors.initials: C
authors.lastname: Eifert
authors.forename: Barbara
authors.initials: B
authors.lastname: Feldmeyer
authors.forename: Markus
authors.initials: M
authors.lastname: Pfenninger
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D005075:Biological Evolution; D057231:Climate Change; D058893:DNA Barcoding, Taxonomic; D004272:DNA, Mitochondrial / Q000235:genetics; D005618:Fresh Water; D014644:Genetic Variation; D005838:Genotype; D005843:Geography; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D008957:Models, Genetic; D008969:Molecular Sequence Data; D012641:Selection, Genetic; D012908:Snails / Q000145:classification* / Q000235:genetics; D013696:Temperature
chemical_list: D004272:DNA, Mitochondrial
keywords: Pyrenees; Radix; climate change; cryptic species; hybrid zone; precipitation gradient