Intraspecific variation among Chinook salmon populations indicates physiological adaptation to local environmental conditions

Understanding interpopulation variation is important to predicting species' responses to climate change. Recent research has revealed interpopulation variation among several species of Pacific salmonids. Here, we tested for local adaptation and countergradient variation by assessing interpopulation variation among six populations of fall-run Chinook salmon from California, Oregon, and Washington (USA). Juvenile fish were reared at three temperatures and five physiological metrics were measured. Statistical associations between the five physiological traits and 15 environmental predictors supported our hypotheses of local adaptation. Notably, latitude was a poor predictor of population physiology. Instead, our results demonstrate that populations from warmer habitats exhibit higher thermal tolerance (i.e., critical thermal maxima), faster growth when warm-acclimated and greater aerobic capacity at high temperatures. Additionally, populations with longer migrations exhibit higher metaboli..., Fish (n = 710, 23.9± 4.25 g) underwent metabolic trials in one of four, 5 L automated swim tunnel respirometers (Loligo, Denmark). The four tunnels were split into two paired systems with two tunnels sharing a single sump and heat pump. Water for each swim tunnel system was pumped (PM700, Danner USA) from the sump into an aerated water bath surrounding each swim tunnel, and then returned to the sump. Sumps were supplied with non-chlorinated fresh water from a designated well and aerated with air stones. The temperature of the sump (and therefore the swim tunnels) was maintained (±0.5°C) by circulating water through a heat pump (model DSHP-7; Aqua Logic Delta Star, USA) using a high-volume water pump (Sweetwater SHE 1.7 Aquatic Ecosystems, USA). In addition, each sump contained a thermostatically controlled titanium heater (TH-800; Finnex, USA). Swim tunnels and associated sump systems were cleaned and sanitized with bleach weekly to reduce potential for bacterial growth.
Dissolved oxyge..., .csv Files can be opened with excel or in R. There are not additional software requirements., # Intraspecific variation among Chinook salmon populations indicates physiological adaptation to local environmental conditions

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There are 3 datasets. One that pertains to growth measurements, one that pertains to CTMax data and the third contains data regarding metabolic performance. The columns and descriptions for these three datasets are below.

Only fish used in the analysis for the Conservation Physiology manuscript are included in this data. This excludes fish which did not recover from the metabolic or CTMax trials or fish from other populations which were measured during the same experimental seasons, which leads to gaps in the individual numbering of trial fish

## Column Specs: Con_Phys_2023_Dryad_CTM_Data.csv

* SEQ: Numerical number, runs from 1 to the end fo the dataset, each row gets its own value
* FISH_NUM: Unique fish identification number, gaps in sequence are due to fish which did not survive recovery, or data from other populations not included in the publica...