DOI: 10.5061/dryad.02r66
title: Data from: Using time series analysis to characterize evolutionary and plastic responses to environmental change: a case study of a shift toward earlier migration date in sockeye salmon

description: Environmental change can shift the phenotype of an organism through either evolutionary or nongenetic processes. Despite abundant evidence of phenotypic change in response to recent climate change, we typically lack sufficient genetic data to identify the role of evolution. We present a method of using phenotypic data to characterize the hypothesized role of natural selection and environmentally driven phenotypic shifts (plasticity). We modeled historical selection and environmental predictors of interannual variation in mean population phenotype using a multivariate state-space model framework. Through model comparisons, we assessed the extent to which an estimated selection differential explained observed variation better than environmental factors alone. We applied the method to a 60-year trend toward earlier migration in Columbia River sockeye salmon Oncorhynchus nerka, producing estimates of annual selection differentials, average realized heritability, and relative cumulative effects of selection and plasticity. We found that an evolutionary response to thermal selection was capable of explaining up to two-thirds of the phenotypic trend. Adaptive plastic responses to June river flow explain most of the remainder. This method is applicable to other populations with time series data if selection differentials are available or can be reconstructed. This method thus augments our toolbox for predicting responses to environmental change.
description: sockeye.datafileThis data comes primarily from the Columbia River DART database managed by the University of Washington (http://www.cbr.washington.edu/dart/dart.html). Column headings: Y=Year of adult migration; D=median migrate date of adult sockeye salmon (DART); S1997=selection differential calculated in R based on the selection function fit to 1997 mark-recapture data; F=mean June flow in cms at Bonneville Dam (DART); FP=day of maximum flow in Julian days, calculated from daily flow data from DART; T=mean June temperature at Bonneville Dam(DART); Umar, Uap,Umay=Upwelling index for March, April, and May at 45N from Pacific Fisheries Environmental Laboratory. 2008. Upwelling Index. Environmental Research Division, NOAA-Fisheries, SWFSC http://www.pfeg.noaa.gov/javamenu.html, accessed June 2008. WRI=total sockeye count at Wells Dam divided by the total count at Rock Island Dam (DART); PDO=Index of the Pacific Decadal Oscillation averaged from Dec-Jun from Mantua, N. 2005. PDO Index, http://jisao.washington.edu/pdo/PDO.latest; NPGO=Di Lorenzo, E., N. Schneider, K. M. Cobb, K. Chhak, P. J. S. Franks, A. J. Miller, J. C. McWilliams et al. 2008. North Pacific Gyre Oscillation NPGO Index available at http://eros.eas.gatech.edu/npgo/; NPI= North Pacific Index, from Trenberth, K., and J. Hurrell. 2009. Boulder, USA, Climate Analysis Section, NCAR. The next set of columns are the difference in the index from year t-4 to year t, except for S4, which is simply shifted by 4 years. CumS4 reflects the cumulative selection at 4-generation intervals up to that year. D.sd is the standard deviation of the migration period, and betaS is the selection differential standardized by the standard deviation of the trait (i.e., D.sd)