title: Strong divergence in trait means but not in plasticity across hatchery and wild populations of sea-run brown trout Salmo trutta.
abstract: There is ample evidence that organisms adapt to their native environment when gene flow is restricted. However, evolution of plastic responses across discrete environments is less well examined. We studied divergence in means and plasticity across wild and hatchery populations of sea-run brown trout (Salmo trutta) in a common garden experiment with two rearing environments (hatchery and a nearly natural experimental stream). Since natural and hatchery environments differ, this arrangement provides an experiment in contemporary adaptation across the two environments. A Q(ST) - F(ST) approach was used to investigate local adaptation in survival and growth over the first summer. We found evidence for divergent selection in survival in 1 year and in body length in both years and rearing environments. In general, the hatchery populations had higher survival and larger body size in both environments. Q(ST) in body size did not differ between the rearing environments, and constitutive divergence in the means was in all cases stronger than divergence in the plastic responses. These results suggest that in this system, constitutive changes in mean trait values are more important for local adaptation than increased plasticity. In addition, ex situ rearing conditions induce changes in trait means that are adaptive in the hatchery, but potentially harmful in the wild, suggesting that hatchery rearing is likely to be a suboptimal management strategy for trout populations facing selection in the stream environment.
authors.affiliation: Department of Population Biology and Conservation Biology Evolutionary Biology Center, Norbyvägen 18D, 752 36 Uppsala, Sweden. bjorn.rogell@ebc.uu.se
authors.forename: Björn
authors.initials: B
authors.lastname: Rogell
authors.forename: Johan
authors.initials: J
authors.lastname: Dannewitz
authors.forename: Stefan
authors.initials: S
authors.lastname: Palm
authors.forename: Erik
authors.initials: E
authors.lastname: Petersson
authors.forename: Jonas
authors.initials: J
authors.lastname: Dahl
authors.forename: Tore
authors.initials: T
authors.lastname: Prestegaard
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Järvi
authors.forename: Anssi
authors.initials: A
authors.lastname: Laurila
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D049628:Body Size / Q000235:genetics; D001947:Breeding; D005398:Fisheries; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats; D010641:Phenotype; D012641:Selection, Genetic; D014337:Trout / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology