DOI: 10.5061/dryad.qrfj6q5mh
title: Data for: Multi-scale relationships in thermal limits within and between two cold-water frog species uncover different trends in physiological vulnerability

description: Critical thermal limits represent an important component of an organism’s
 capacity to cope with future temperature changes. Understanding the
 drivers of variation in these traits may uncover patterns in physiological
 vulnerability to climate change. Local temperature extremes have emerged
 as a major driver of thermal limits, although their effects can be
 mediated by the exploitation of fine-scale spatial variation in
 temperature through behavioral thermoregulation. Here, we investigated
 thermal limits along elevation gradients within and between two cold-water
 frog species (Ascaphus spp.), one with a coastal distribution (A. truei)
 and the other with a continental range (A. montanus). We quantified
 thermal limits for over 700 tadpoles, representing multiple populations
 from each species. We combined local temporal and fine-scale spatial
 temperature data to quantify local thermal landscapes (i.e.,
 thermalscapes), including the opportunity for behavioral thermoregulation.
 Lower thermal limits for either species could not be reached
 experimentally reached without the water freezing, suggesting that cold
 tolerance is &lt;0.3℃. In contrast, upper thermal limits varied among
 populations, but this variation only reflected local temperature extremes
 in A. montanus, perhaps due to greater variation in stream temperatures
 across its range. Lastly, we found minimal fine-scale spatial variability
 in temperature, suggesting limited opportunity for behavioral
 thermoregulation and thus increased vulnerability to warming for all
 populations. By quantifying local thermalscapes, we uncovered different
 trends in the relative vulnerability of populations across elevation for
 each species. In A. truei, physiological vulnerability decreased with
 elevation, whereas in A. montanus, all populations were equally
 physiologically vulnerable. These results highlight how similar
 environments can differentially shape physiological tolerance and patterns
 of vulnerability of species, and in turn, impact their vulnerability to
 future warming. 
description: See associated manuscript for full Methods details.
 Temporal Stream Temperature Measurements
 These data were collected using two temperature loggers (HOBO
 pendant UA-001-64, Onset Corporation) at each end of sampled stream
 reaches (~100m) that recorded temperatures every four hours. We visually
 inspected the time-series temperature logger data for error and screened
 the data using standard deviation time series plots before calculating: 1)
 the absolute minimum daily temperature and absolute maximum daily
 temperature, and 2) the average of the ten consecutive coldest and the
 average of the ten consecutive warmest days. Spatial
 Stream Temperature Measurements We measured
 temperatures at a minimum of 100 points using a field temperature probe
 (ODO, YSI Incorporated, Yellow Springs, Ohio) that was placed in the water
 at the interface of the stream substrate, reflecting the microhabitat of
 <em>Ascaphus</em> tadpoles. Temperature measurements were made
 along transects of pre-identified <em>Ascaphus</em> spp.
 habitat along the stream reach. Along the stream transects, we measured
 the temperature of the stream at intervals determined by stream width
 (&lt;3m wide: measurements every 0.5m; &gt;3m wide: measurements
 every 1m). For each measurement, we randomly offset the measurements from
 the interval along the stream transect using a random number table. For
 streams &lt;3m wide, the offset did not exceed 25cm. For streams
 &gt;3m wide, the offset did not exceed 50cm. For example, if a narrow
 (&lt;3m) stream at transect 1, interval 3 (1.5m from stream bank) had
 an offset of -21, the measurement would be taken at 1.29m from the stream
 bank. For transect points that were obstructed (e.g., by a large rock), we
 noted the obstruction and measured the point directly upstream. We
 opportunistically sampled visible seeps or confluences to capture any
 potential thermal anomalies present outside of designated transects to
 ensure full sampling of existing spatial temperature variation available
 to tadpoles. Thermal Limit Experiments
 Tadpoles collected from each population were held and tested
 separately. Tadpoles were held at 8℃ (a commonly experienced temperature)
 for three days before experiments occurred. CTmin and CTmax were measured
 using temperature ramping experiments at a starting temperature of 8℃ and
 a ramping rate of ~0.3℃/minute. To ramp water temperature up for CTmax
 experiments, we used the PID temperature controller with a solid-state
 relay attached to a titanium heating rod. To ramp water temperature down
 for LTL experiments, we added ice at pre-determined intervals to the
 experiment tank (i.e., not the containers holding the tadpoles), adjusting
 the amount of ice needed to reach our desired cooling rate. Critical
 thermal limits were defined as the temperature at which tadpoles no longer
 responded to a tactile stimulus. Upon reaching their thermal limits,
 tadpoles were returned to holding temperatures and allowed to recover for
 up to an hour.
description: # Multi-scale relationships in thermal limits within and between two
 cold-water frog species uncover different trends in physiological
 vulnerability *** There are 5 datasets associated with this study. They
 each have their own README files. Please see each individual file's
 README for more information. Note: Empty cells denote missing data.
 Missing data are explained in the associated manuscript. ## Description of
 the data and file structure Four datasets: 1. CTmin\_BothSpecies - CTmin
 data 2. CTmax\_BothSpecies - CTmax data 3. Metrics\_ThermalLimits -
 temperature logger data for all sites 4. MT\_MicroTemp - spatial
 temperature data for sites in Montana 5. OR\_MicroTemp - spatial
 temperature data for sites in Oregon ## Sharing/Access information
 Correspondence: Amanda Cicchino, Department of Biology, Colorado State
 University, Fort Collins, CO 80521, USA; Email:
 cicchino@rams.colostate.edu; ORCID: 0000-0003-0170-829X