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dc.contributor.authorØstbye, Kjartan
dc.contributor.authorHarrod, Chris
dc.contributor.authorGregersen, Finn
dc.contributor.authorKlepaker, Tom
dc.contributor.authorSchulz, Michael
dc.contributor.authorSchluter, Dolph
dc.contributor.authorVøllestad, Leif A
dc.PublishedBMC Evolutionary Biology. 2016 May 13;16(1):102eng
dc.description.abstractBackground Studying how trophic traits and niche use are related in natural populations is important in order to understand adaptation and specialization. Here, we describe trophic trait diversity in twenty-five Norwegian freshwater threespine stickleback populations and their putative marine ancestor, and relate trait differences to postglacial lake age. By studying lakes of different ages, depths and distance to the sea we examine key environmental variables that may predict adaptation in trophic position and habitat use. We measured trophic traits including geometric landmarks that integrated variation in head shape as well as gillraker length and number. Trophic position (Tpos) and niche use (α) were estimated from stable isotopes (δ13C, δ15N). A comparison of head shape was also made with two North American benthic-limnetic species pairs. Results We found that head shape differed between marine and freshwater sticklebacks, with marine sticklebacks having more upturned mouths, smaller eyes, larger opercula and deeper heads. Size-adjusted gillraker lengths were larger in marine than in freshwater stickleback. Norwegian sticklebacks were compared on the same head shape axis as the one differentiating the benthic-limnetic North American threespine stickleback species pairs. Here, Norwegian freshwater sticklebacks with a more “limnetic head shape” had more and longer gillrakers than sticklebacks with “benthic head shape”. The “limnetic morph” was positively associated with deeper lakes. Populations differed in α (mean ± sd: 0.76 ± 0.29) and Tpos (3.47 ± 0.27), where α increased with gillraker length. Larger fish had a higher Tpos than smaller fish. Compared to the ecologically divergent stickleback species pairs and solitary lake populations in North America, Norwegian freshwater sticklebacks had similar range in Tpos and α values, but much less trait divergences. Conclusions Our results showed trait divergences between threespine stickleback in marine and freshwater environments. Freshwater populations diverged in trophic ecology and trophic traits, but trophic ecology was not related to the elapsed time in freshwater. Norwegian sticklebacks used the same niches as the ecologically divergent North American stickleback species pairs. However, as trophic trait divergences were smaller, and not strongly associated with the ecological niche, ecological adaptations along the benthic-limnetic axis were less developed in Norwegian sticklebacks.en_US
dc.publisherBioMed Centralen_US
dc.rightsAttribution CC BY 4.0eng
dc.subjectAdaptive radiationeng
dc.subjectNatural selectioneng
dc.subjectEcological nicheeng
dc.subjectStable isotopic analysiseng
dc.subjectIsostatic uplifteng
dc.subjectPleistocene ice sheeteng
dc.subjectBenthic-limnetic stickleback species pairseng
dc.titleThe temporal window of ecological adaptation in postglacial lakes: a comparison of head morphology, trophic position and habitat use in Norwegian threespine stickleback populationsen_US
dc.typePeer reviewed
dc.typeJournal article
dc.rights.holderCopyright Østbye et al. 2016en_US
dc.subject.nsiVDP::Medisinske Fag: 700en_US

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