Collection of data
We identified published studies documenting the rate of change in
whole-body measurements of thermal tolerance in response to manipulation
of ambient temperature. Specifically, we sought to identify papers where
the study organisms, having been acclimated to an initial temperature
for a given period of time, were transferred to a ‘new’ temperature,
after which thermal tolerance was measured on subsamples of these
individuals at different points in time. Our search criteria included
studies that addressed tolerance of both high and low temperatures and
performed measurements of critical temperatures (i.e. CTmax, CTmin),
time to death or immobility, or mortality rate at a stressful
temperature. An additional criterion was that measurements of thermal
tolerance were made at a minimum of three time points. Using these
criteria, relevant papers were identified using the following procedure.
First, we included eight papers identified by Burton et al. (2022) that
were based on a search in Web of Science (see Burton et al. for
procedure). Second, we conducted two searches on Google Scholar during
January 2022. In the first search, we used the terms ”temperature” and
”rate of acclimation”. The 739 hits were sorted based on relevance, and
the first 200 abstracts were scanned for inclusion, resulting in a total
of 55 papers (none of these appeared among the last 30 scanned
abstracts). In the second search, we used the terms ”temperature”,
”acclimation”, ”time course” and ”critical”. This resulted in 30200
hits, which also were sorted based on relevance, and where the first 200
abstracts were scanned for inclusion. For this second search, 7
additional papers were identified (the majority of relevant hits had
been identified in the initial search). Finally, the reference lists of
papers identified above were scanned for reference to additional papers
not located in any of the previous searches, resulting in a further 18
papers. Thus, a total of 88 papers were identified during this
procedure. For each paper, we determined whether it presented the
required data in an accessible form. Fifty-nine of the papers identified
above were found to contain suitable data. Many of these contained data
from several experiments (different species and/or different acclimation
temperatures), and data from a total of 308 acclimation experiments from
a total of 114 species were extracted from these papers. For most of the
papers, data were presented in figure format only, usually as the mean
tolerance of groups of individuals that had experienced the ‘new’
temperature for differing lengths of time prior to being measured for
the chosen tolerance trait. We digitized such data using the
WebPlotDigitizer (https://apps.automeris.io/wpd/). In addition to
thermal tolerance data we extracted information for the following
variables: taxonomic class, species name, mean body mass of individuals
used in the experiment, and acclimation temperature. For experiments
where body mass information was absent we used the following procedure
to obtain such data. First, we searched for information on minimum and
maximum adult body size (length or mass) for the species in question. If
only data on body length were available, we searched for allometries
between length and mass for that species, or for species within the same
genus, and used these to convert body lengths to mass. We then
calculated the mean of the minimum and maximum body mass values. If no
data on minimum or maximum size was found, we searched for studies that
presented body sizes of adult individuals during field surveys and used
the mean of these. Combining body size estimates from each of these
sources yielded measurements for 290 of the 308 experiments described
above, representing a total of 107 species from the following classes of
ectotherms; amphibians, reptiles, insects, osteichtyes and malacostraca.
For simplicity the latter two will be referred to as fishes and
crustaceans, respectively.