DOI: 10.5061/dryad.crjdfn3c4
title: Data for: Local environments, not hybridization, influence cardiac performance of native trout under acute thermal stress

description: Climate-induced expansion of invasive hybridization (breeding between
 invasive and native species) poses a significant threat to the persistence
 of many native species worldwide. In the northern US Rocky Mountains,
 hybridization between native cutthroat trout and non-native rainbow trout
 has increased in recent decades due, in part, to climate-driven increases
 in water temperature. It has been postulated that invasive hybridization
 may enhance physiological tolerance to climate-induced thermal stress
 because laboratory studies indicate that rainbow trout have a higher
 thermal tolerance than cutthroat trout. Here, we assessed whether invasive
 hybridization improves cardiac performance response to acute water
 temperature stress of native wild trout populations. We collected trout
 from four streams with a wide range of non-native admixture among
 individuals and with different temperature and streamflow regimes in the
 upper Flathead River drainage, USA. We measured individual cardiac
 performance (maximum heart rate, “MaxHR”, and temperature at arrhythmia,
 “ArrTemp”) during laboratory trials with increasing water temperatures
 (10-28°C). Across the study populations, we observed substantial variation
 in cardiac performance of individual trout when exposed to thermal stress.
 Notably, we found significant differences in the cardiac response to
 thermal regimes among native cutthroat trout populations, suggesting the
 importance of genotype-by-environment interactions in shaping the
 physiological performance of native cutthroat trout. However, rainbow
 trout admixture had no significant effect on cardiac performance (MaxHR
 and ArrTemp) within any of the populations. Our results suggest that
 invasive hybridization with a warmer-adapted species does not enhance the
 cardiac performance of native trout under warming conditions. Maintaining
 numerous populations across thermally and hydrologically diverse stream
 environments will be crucial for native trout to adapt and persist in a
 warming climate.
description: # Data for: Local Environments, not hybridization, influence cardiac
 performance of native trout under acute thermal stress
 [https://doi.org/10.5061/dryad.crjdfn3c4](https://doi.org/10.5061/dryad.crjdfn3c4) Paper: Local environments, not invasive hybridization, influence cardiac performance of native trout under acute thermal stress Authors: Jeffrey T. Strait, Jared A. Grummer, Nicholas F. Hoffman, Clint C. Muhlfeld, Shawn R. Narum, and Gordon Luikart Description: This README file describes the data accompanying the above publication. Files: 1\. data folder: Includes the csv file with the containing information for each fish tested as part of the study. 1a. dataset: Cardic_admixture_data.csv population - the creek in which the individual was sampled LabID - unique laboratory ID used to track genetic data year - the year in which the individual was captured and cardiac performance test conducted prbt - the estimate of proportion Rainbow Trout admixture (hybridization) from RAD-capture genotyping weight.g - the mass in grams of each individual Arr.Temp - the temperature (celsius) at which the individual's cardiac signal became arrhythmic Max.HR - the maximum heart rate measured for the individual during the cardiac performance trial Max.HR.MC the mass-corrected maximum heart rate calculated using the following formula: (measured heart rate) * ( (weight (g) / 11.8) ^ 0.1 )