Studies of parallel evolution are seldom able to disentangle the influence of cryptic environmental variation from that of evolutionary history; whereas the unique life history of pink salmon (Oncorhynchus gorbuscha) presents an opportunity to do so. All pink salmon mature at age two and die after breeding. Hence, pink salmon breeding in even years are completely reproductively isolated from those breeding in odd years, even if the two lineages breed in same location. We used time series (mean = 7 years, maximum = 74 years) of paired even- and odd-year populations from 36 rivers spanning over 2000 km to explore parallelism in migration timing, a trait with a strong genetic basis. Migration timing was highly parallel, being determined almost entirely by local environmental differences among rivers. Interestingly, interannual changes in migration timing different somewhat between lineages. Overall, our findings indicate very strong determinism, with only a minor contribution of contingency.
Estimated median date of return
Median date of return estimated by fitting a normal distribution to daily count data for each year and river combination. Column "year" gives the year the data were sampled and "river" gives the sampling location or weir at which data were sampled. "Run" is determined based on whether the data was collected during an even year (even-year lineage) or odd year (odd-year lineage). Columns "lat" and "long" are latitude and longitude, respectively, and "z_score_lat" is the z-score of latitude. Column "day_of_year" is the estimated median return date, recorded as Julian date.
pink_salmon_median_date_return.csv
Daily count of migrating pink salmon
Raw daily count data for each year and river combination. Column "river" provided the name of the river or weir where data were sampled and "year" provides the year in which sampling occurred. Column "count" provides the number of pink salmon that migrated upstream through the weir on the date given in column "day_of_year" (as Julian date). Column "original notes" provides any notes originally recorded by weir staff, and often denotes problems with weir function, such as early removal or flooding. Column "cumulative_count" provides the cumulative sum of pink salmon that have migrated upstream so far in that river thus far in that year. As detailed in the supplemental information accompanying the article, this dataset is a compilation of data downloaded from publicly available datasets, published papers, or provided to us from personal contacts. They were originally collected by the Alaska Department of Fish and Game (ADF&G; provided by Mark Witteveen, Leon Shaul, or downloaded from the ADF&G website), Fisheries and Oceans Canada (DFO; provided by David Peacock), Nisga'a Fisheries and Wildlife (provided by Edward Desson & Richard Alexander), and the U.S. Fish and Wildlife Service. Please refer to table S1 for the specific data source for each river.
pink_salmon_raw_daily_counts.csv
River distance
The river distance between the ocean and the weir. Column "river" provides river or weir name and "river_distance_m" provides the distance in meters. Distances were provided in original data sources or estimated from google maps as detailed in the supplemental information accompanying the article. In some cases river distance could not be determined, in these cases the "river_distance_m" column is left blank.
pink_salmon_river_distance.csv
