Grant: Discovery Grants Program - Individual

Salmon are often thought to be locally adapted due to their natal homing and remarkable life history variation; yet little empirical evidence exists to support this. Additive genetic variance is an important component of adaptation, yet environment, epigenetics, non-additive genetics, and phenotypic plasticity also have roles in rapid evolution and local adaptation. I propose to use molecular, population, and quantitative genetic methods combined with field measurements to quantify the various genetic, epigenetic and environmental effects on maturation and migration life history traits in Pacific salmon. Pacific salmon are ideal model organisms for my research as they exhibit extreme life history variation and experience strong selection (since they die after spawning); my proposed research will capitalize on my experience in salmon genetics, ecology and physiology to assess rapid evolution and local adaptation in Pacific salmon. A key prerequisite for local adaptation is reproductive isolation, thus I will measure both genetic and life history divergence among populations: The comparison of the two will determine whether trait differences are due to drift or are adaptive. This will provide compelling evidence for local adaptation, but it is essentially correlative. Thus I will also use breeding experiments, molecular marker-based quantitative genetics (QTLs), and reaction norm analyses to estimate additive and non-additive genetic effects, gene number, and phenotypic plasticity for reproductive and migratory traits. In a parallel research program, I will quantify gene transcription variation among populations. I believe that epigenetic and non-additive genetic effects on transcription may provide a unified mechanistic explanation for rapid evolution and phenotypic plasticity. Such a novel finding would represent a revolutionary conceptual advance in our understanding of local adaptation. The integration of genetic and transcriptional analyses with field measures will test the link between life history variation and local adaptation, addressing a question central to our understanding of the evolution of life history variation in salmon: are salmon runs locally adapted or are they simply highly plastic?