title: IBSEM: An Individual-Based Atlantic Salmon Population Model.
abstract: Ecology and genetics can influence the fate of individuals and populations in multiple ways. However, to date, few studies consider them when modelling the evolutionary trajectory of populations faced with admixture with non-local populations. For the Atlantic salmon, a model incorporating these elements is urgently needed because many populations are challenged with gene-flow from non-local and domesticated conspecifics. We developed an Individual-Based Salmon Eco-genetic Model (IBSEM) to simulate the demographic and population genetic change of an Atlantic salmon population through its entire life-cycle. Processes such as growth, mortality, and maturation are simulated through stochastic procedures, which take into account environmental variables as well as the genotype of the individuals. IBSEM is based upon detailed empirical data from salmon biology, and parameterized to reproduce the environmental conditions and the characteristics of a wild population inhabiting a Norwegian river. Simulations demonstrated that the model consistently and reliably reproduces the characteristics of the population. Moreover, in absence of farmed escapees, the modelled populations reach an evolutionary equilibrium that is similar to our definition of a 'wild' genotype. We assessed the sensitivity of the model in the face of assumptions made on the fitness differences between farm and wild salmon, and evaluated the role of straying as a buffering mechanism against the intrusion of farm genes into wild populations. These results demonstrate that IBSEM is able to capture the evolutionary forces shaping the life history of wild salmon and is therefore able to model the response of populations under environmental and genetic stressors.
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, N-5817, Bergen, Norway; School of Mechanical Engineering, University of Birmingham, B15 2TT, Birmingham, United Kingdom.
authors.forename: Marco
authors.initials: M
authors.lastname: Castellani
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, N-5817, Bergen, Norway; Department of Biology, University of Bergen, Bergen, Norway; International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
authors.forename: Mikko
authors.initials: M
authors.lastname: Heino
authors.affiliation: Marine Scotland Science, Freshwater Laboratory, Faskally, Pitlochry, PH16 5LB, Scotland, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Gilbey
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Araki
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, N-5817, Bergen, Norway.
authors.forename: Terje
authors.initials: T
authors.lastname: Svåsand
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, N-5817, Bergen, Norway; Department of Biology, University of Bergen, Bergen, Norway.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Glover
mesh_terms: D063147:Animal Distribution; D000818:Animals; D051456:Gene Flow; D005828:Genetics, Population; D005838:Genotype; D008018:Life Cycle Stages; D008962:Models, Theoretical; D009664:Norway; D011157:Population Dynamics; D045483:Rivers; D020317:Salmo salar / Q000235:genetics*