title: Strong and consistent natural selection associated with armour reduction in sticklebacks.
abstract: Measuring the strength of natural selection is tremendously important in evolutionary biology, but remains a challenging task. In this work, we analyse the characteristics of selection for a morphological change (lateral-plate reduction) in the threespine stickleback Gasterosteus aculeatus. Adaptation to freshwater, leading with the reduction or loss of the bony lateral armour, has occurred in parallel on numerous occasions in this species. Completely-plated and low-plated sticklebacks were introduced into a pond, and the phenotypic changes were tracked for 20 years. Fish from the last generation were genotyped for the Ectodysplasin-A (Eda) locus, the major gene involved in armour development. We found a strong fitness advantage for the freshwater-type fish (on average, 20% fitness advantage for the freshwater morph, and 92% for the freshwater genotype). The trend is best explained by assuming that this fitness advantage is maximum at the beginning of the invasion and decreases with time. Such fitness differences provide a quantifiable example of rapid selection-driven phenotypic evolution associated with environmental change in a natural population.
authors: Department of Biology, Center for Ecology and Evolutionary Synthesis, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway. lerouzic@legs.cnrs-gif.fr
authors: Arnaud
authors: A
authors: LE Rouzic
authors: Kjartan
authors: K
authors: Østbye
authors: Tom O
authors: TO
authors: Klepaker
authors: Thomas F
authors: TF
authors: Hansen
authors: Louis
authors: L
authors: Bernatchez
authors: Dolph
authors: D
authors: Schluter
authors: L Asbjørn
authors: LA
authors: Vøllestad
mesh_terms: D000220:Adaptation, Biological; D000413:Alaska; D000818:Animals; D005075:Biological Evolution; D016001:Confidence Intervals; D053331:Ectodysplasins / Q000235:genetics*; D005618:Fresh Water; D056084:Genetic Fitness; D005819:Genetic Markers; D005828:Genetics, Population; D005838:Genotype; D016013:Likelihood Functions; D008957:Models, Genetic; D009664:Norway; D010641:Phenotype; D011157:Population Dynamics; D012623:Seawater; D012641:Selection, Genetic; D023701:Smegmamorpha / Q000033:anatomy & histology* / Q000235:genetics; D013997:Time Factors
chemical_list: D053331:Ectodysplasins; D005819:Genetic Markers