DOI: 10.5061/dryad.z34tmpgg3
title: To rise to temperature: Variation in temperature effects within and among populations

description: Temperature drives physiological changes on three timescales: acute,
 acclimatory and evolutionary. Acutely, passive temperature effects often
 dictate an expected two-fold increase in metabolic processes for every
 10°C increase (Q10). Yet for acclimatory or evolutionary time scales,
 selection often mitigates these acute effects. This selection also should
 concomitantly reduce interindividual variation. However, the individual
 variation in physiological trait thermal sensitivity is not well
 characterized. Here we quantified physiological responses to a 16°C
 temperature difference across nine thermally distinct Fundulus
 heteroclitus populations. Traits included whole animal metabolism (WAM),
 critical thermal maximum (CTmax), and substrate-specific cardiac
 metabolism measured in approximately 350 individuals. These traits exhibit
 high variation among both individuals and populations that depends on
 acclimation temperature. Thermal sensitivity or Q10 variation is
 unexpected and ranges from 0.6 to 5.4 for WAM. Thus, with a 16°C
 temperature increase, some individuals have the same or lower metabolic
 rates while others have metabolic rates almost seven-fold higher (Q10 =
 5.4). Furthermore, a significant portion of this variation is related to
 habitat temperature, such that warmer populations have a significantly
 lower Q10 for WAM and CTmax than colder populations. These data support a
 novel hypothesis: individual variation in thermal sensitivity reflects
 different physiological strategies to respond to environmental temperature
 variation and provides the potential for many different adaptive responses
 to temperature.
description: For temperature data, Hobo Data loggers were deployed over August
 2018 at the listed sites. For each location, loggers collected one measure
 every 5 minutes. Time data was matched with the high tide times per day
 and the mean minimum high tide temperatures were extracted using HOBOware
 software.  For whole animal metabolism, data was
 collected using a PreSens oxygen meter, with PreSens output file that was
 processed as the lowest tenth percent value in a distribution of metabolic
 rates. For CTmax, the temperature at which fish lost
 equilibrium was recorded. For cardiac metabolism, data
 was collected using a PreSens oxygen meter with PreSens output file. These
 files were processed to extract the slope of the last 3 minutes of oxygen
 consumption. Full methods can be found in the
 associated manuscript.
description: Abbreviations: MMT = mean minimum
 temperature Temp = acclimation temperature (12 ot
 28) aug2018_temp = habitat temperature
 pop = population mass = mass in grams
 (g) length = length in mm
 tenyr_mean_temp = mean temperature across 10 years extracted from
 closest NOAA site pair = warm/cold populations close
 together with significant temperature difference
 mt_haplotype = likely mitochondrial haplotype based on location
 and geographic break (not confirmed molecularly)
 temp_var = variance in ten year NOAA temperature data
 accl_order = order the fish were acclimated for
 measurement