Atlantic salmon maturation: contributions from large-effect locus and environmental factors in influencing maturation age in two populations in a common garden setting.

Abstract

The Atlantic salmon (Salmo salar) is a unique species with regards to studies on life history, as it not only shows significant variation in age at maturity but also because a large proportion of the variation in this trait has been associated with a single genetic locus, vgll3. While this association is now well known, less is known about this gene’s mechanistic pathway and how it interacts with other environmental or genetic factors. To follow up on vgll3 as a large-effect locus for age at maturity in Atlantic salmon, we present a long-term common garden experiment aimed at studying the sources of variation for this trait, covering different vgll3 genotypes across two environmental temperature regimes, two feed treatments, and two populations-of-origin. We show that the effect of vgll3 genotype on maturation timing in male Atlantic salmon is consistent across the temperature treatments and populations. Additionally, we show a population-dependent effect of temperature, with the northern population having a smaller difference in maturation rates between the two temperature regimes. Finally, we discuss the relative contribution of these environmental and genetic factors to Atlantic salmon maturation timing.