DOI: 10.5061/dryad.gtht76hqq
title: Rates of phenotypic plasticity in thermal tolerance

description: An individual's fitness cost associated with environmental change
 likely depends on the rate of adaptive phenotypic plasticity, and yet our
 understanding of plasticity rates in an ecological and evolutionary
 context remains limited. We provide the first quantitative synthesis of
 existing plasticity rate data, focusing on acclimation of temperature
 tolerance in ectothermic animals, where we demonstrate applicability of a
 recently proposed analytical approach. The analyses reveal considerable
 variation in plasticity rates of this trait among species, with half-times
 (how long it takes for the initial deviation from the acclimated phenotype
 to be reduced by 50% when individuals are shifted to a new environment)
 ranging from 3.7 to 770.2 h. Furthermore, rates differ among higher taxa,
 being higher for amphibians and reptiles than for crustaceans and fishes,
 and with insects being intermediate. We argue that a more comprehensive
 understanding of phenotypic plasticity will be attained through increased
 focus on the rate parameter.
description: Potentially 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 by Google Scholar based on
 relevance, and the first 200 abstracts were scanned for inclusion. 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. From both
 these searches, decisions of inclusion at this stage were made based on
 whether the abstract contained information suggesting that the study
 organisms had been acclimated to an initial temperature for a given period
 of time, and then transferred to a ‘new’ temperature, after which thermal
 tolerance was measured on subsamples of these individuals at different
 points in time. The first search resulted in a total of 55 papers (none of
 these appeared among the last 30 scanned abstracts), whereas the second
 search identified an additional seven papers (the majority of relevant
 hits had been identified in the initial search). Finally, the reference
 lists of papers identified above were manually scanned for reference to
 additional papers not located in any of the previous searches where the
 titles indicated that they might contain the information required as
 indicated above. This resulted in a further 18 papers. Thus, a total of 88
 papers were identified during this procedure. For each of these, we
 obtained the full paper and checked whether it presented the required data
 in an accessible form. Our selection criterium was that the study
 presented data on thermal tolerance (measured as critical temperatures
 (i.e. CT<sub>max</sub>, CT<sub>min</sub>), time to
 death/immobility of individuals, or mortality rate at a stressful
 temperature in groups of organisms) at a minimum of three time-points at
 and following movement from one rearing temperature to another one.
 Fifty-nine of the 88 papers were found to satisfy these criteria. Many of
 these contained data from several experiments (different species and/or
 different acclimation temperatures). It should be noted that we did not
 attempt to follow the PRISMA guidelines for meta-analyses. Our intention
 was to conduct a more exploratory and descriptive first quantitative
 synthesis of studies on rates of plasticity, that with a reasonable effort
 compiled sufficient amounts of data to address our main questions (1)
 whether the change in temperature tolerance in response to a shift in
 ambient temperature is best approximated by exponential or linear decay
 models, and (2) whether there are any phylogenetic patterns in this rate.
 Since these are novel questions, none of the empirical studies identified
 in our literature search actually address these questions themselves.
 Rather, individual studies typically focus on a single or a few highly
 related species, and data are usually presented in a descriptive manner
 without any formal statistical quantification of plasticity rates. Thus,
 there should be no reason for the actual results of a study to influence
 the decision to publish them. The only exception would be for studies that
 test for but fail to observe any acclimation response. However, even if
 such studies may be underrepresented in the literature, rates of
 acclimation cannot be calculated in such cases and thus these would have
 been excluded from the current study regardless. We therefore consider the
 risk of publication bias or procedures used for data collection in
 influencing our conclusions to be limited.
   Burton,
 T., Ratikainen, I. I.,
 & Einum, S. (2022). Environmental change and the rate of
 phenotypic plasticity. Global Change Biology,
 28, 5337–5345. https://doi.org/10.1111/gcb.16291