title: Genomic population structure of freshwater-resident and anadromous ide (Leuciscus idus) in north-western Europe.
abstract: Climate change experts largely agree that future climate change and associated rises in oceanic water levels over the upcoming decades, will affect marine salinity levels. The subsequent effects on fish communities in estuarine ecosystems however, are less clear. One species that is likely to become increasingly affected by changes in salinity is the ide (Leuciscus idus). The ide is a stenohaline freshwater fish that primarily inhabits rivers, with frequent anadromous behavior when sea salinity does not exceed 15%. Unlike most other anadromous Baltic Sea fish species, the ide has yet to be subjected to large-scale stocking programs, and thus provides an excellent opportunity for studying the natural population structure across the current salinity gradient in the Danish Belts. To explore this, we used Genotyping-by-Sequencing to determine genomic population structure of both freshwater resident and anadromous ide populations in the western Baltic Sea region, and relate the results to the current salinity gradient and the demographic history of ide in the region. The sample sites separate into four clusters, with all anadromous populations in one cluster and the freshwater resident populations in the remaining three. Results demonstrate high level of differentiation between sites hosting freshwater resident populations, but little differentiation among anadromous populations. Thus ide exhibit the genomic population structure of both a typical freshwater species, and a typical anadromous species. In addition to providing a first insight into the population structure of north-western European ide, our data also (1) provide indications of a single illegal introduction by man; (2) suggest limited genetic effects of heavy pollution in the past; and (3) indicate possible historical anadromous behavior in a now isolated freshwater population.
authors.affiliation: Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5-7 1350 Copenhagen K Denmark.
authors.forename: Mikkel
authors.initials: M
authors.lastname: Skovrind
authors.affiliation: Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5-7 1350 Copenhagen K Denmark.
authors.forename: Morten Tange
authors.initials: MT
authors.lastname: Olsen
authors.affiliation: Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5-7 1350 Copenhagen K Denmark.
authors.forename: Filipe Garrett
authors.initials: FG
authors.lastname: Vieira
authors.affiliation: Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5-7 1350 Copenhagen K Denmark.
authors.forename: George
authors.initials: G
authors.lastname: Pacheco
authors.affiliation: Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5-7 1350 Copenhagen K Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Carl
authors.affiliation: Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5-7 1350 Copenhagen K Denmark.
authors.forename: M Thomas P
authors.initials: MT
authors.lastname: Gilbert
authors.affiliation: Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5-7 1350 Copenhagen K Denmark.
authors.forename: Peter Rask
authors.initials: PR
authors.lastname: Møller
keywords: Anadromous; Genotyping‐by‐Sequencing; Leuciscus idus; genomic population structure; salinity; teleost