title: Sticklebacks adapted to divergent osmotic environments show differences in plasticity for kidney morphology and candidate gene expression.
abstract: Novel physiological challenges in different environments can promote the evolution of divergent phenotypes, either through plastic or genetic changes. Environmental salinity serves as a key barrier to the distribution of nearly all aquatic organisms, and species diversification is likely to be enabled by adaptation to alternative osmotic environments. The threespine stickleback (Gasterosteus aculeatus) is a euryhaline species with populations found both in marine and freshwater environments. It has evolved both highly plastic and locally adapted phenotypes due to salinity-derived selection, but the physiological and genetic basis of adaptation to salinity is not fully understood. We integrated comparative cellular morphology of the kidney, a key organ for osmoregulation, and candidate gene expression to explore the underpinnings of evolved variation in osmotic plasticity within two populations of sticklebacks from distinct salinity zones in the Baltic Sea: the high salinity Kattegat, representative of the ancestral marine habitat; and the low salinity Bay of Bothnia. A common-garden experiment revealed that kidney morphology in the ancestral high-salinity population had a highly plastic response to salinity conditions whereas this plastic response was reduced in the low-salinity population. Candidate gene expression in kidney tissue revealed a similar pattern of population-specific differences, with a higher degree of plasticity in the native high-salinity population. Together these results suggest that renal cellular morphology has become canalized to low salinity, and that these structural differences may have functional implications for osmoregulation.
authors.affiliation: Fisheries and Marine Resource Technology Discipline, Khulna University, Khulna 9208, Bangladesh.|Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki 00014, Finland.
authors.forename: M Mehedi
authors.initials: MM
authors.lastname: Hasan
authors.affiliation: Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki 00014, Finland.
authors.forename: Jacquelin
authors.initials: J
authors.lastname: DeFaveri
authors.affiliation: Institute of Biotechnology & Laboratory Animal Centre, University of Helsinki, Helsinki 00014, Finland.
authors.forename: Satu
authors.initials: S
authors.lastname: Kuure
authors.affiliation: Department of Pathology, University of Helsinki, Helsinki 00014, Finland.
authors.forename: Surjya N
authors.initials: SN
authors.lastname: Dash
authors.affiliation: Department of Pathology, University of Helsinki, Helsinki 00014, Finland.
authors.forename: Sanna
authors.initials: S
authors.lastname: Lehtonen
authors.affiliation: Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki 00014, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Merilä
authors.affiliation: Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki 00014, Finland scott.mccairns@inra.fr.|ESE, Ecology and Ecosystem Health, INRA, Agrocampus Ouest, Rennes 35042, France.
authors.forename: R J Scott
authors.identifier: 0000-0002-0392-7413
authors.initials: RJS
authors.lastname: McCairns
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D003718:Denmark; D005387:Finland; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D007668:Kidney / Q000033:anatomy & histology / Q000502:physiology; D064587:Osmoregulation; D010641:Phenotype; D054712:Salinity; D023701:Smegmamorpha / Q000033:anatomy & histology* / Q000235:genetics / Q000502:physiology*
chemical_list: D029941:Fish Proteins
keywords: Adaptive plasticity; Kidney morphology; Local adaptation; Osmoregulation