Evolutionary Demography and Phenology in a Wild Steelhead Population

Determining how phenotypic variation affects adaptive evolution and demographic dynamics of wild populations has been limited by the difficulty in linking genotypes and phenotypes to fitness. We explore the relationships between genotype and life history in a wild anadromous steelhead (Oncorhynchus mykiss) population from southeastern Alaska. We combine observations on size and migration timing obtained over 12 years from juveniles and adults with genotypic information extracted from DNA microsatellites to generate a multi-generation population pedigree, to estimate genetic and environmental variances underlying phenotypic variation in these traits, and to characterize natural selection on life history and phenology. We attempt to use a discrete-time structured population model to estimate the contributions of individual fish to population productivity by relating variation in fish characteristics to variation in demographic rates. These analyses should permit us to decompose variation in fitness into survival, growth rate and fecundity components, thereby illuminating linkages between population dynamics, life history variation, and evolution of quantitative characters in wild steelhead.