A simple method to account for thermal boundary layers during the estimation of CTmax in small ectotherms
Loading...
Date
Authors
Corley, Rebecca B.
Dawson, Will
Bishop, Tom R.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
As temperatures rise, understanding how ectotherms will become impacted by thermal stress is of critical
importance. In this context, many researchers quantify critical temperatures – these are the upper (CTmax) and
lower (CTmin) thermal limits at which organisms can no longer function. Most studies estimate CTs using bathbased
methods where organisms are submerged within a set thermal environment. Plate-based methods (i.e. hot
plates), however, offer huge opportunity for automation and are readily available in many lab settings. Plates,
however, generate a unidirectional thermal boundary layer above their surface which means that the temperatures
experienced by organisms of different sizes is different. This boundary layer effect can bias estimates of
critical temperatures. Here, we test the hypothesis that biases in critical temperature estimation on hot plates are
driven by organism height. We also quantify the composition of the boundary layer in order to correct for these
biases. We assayed four differently sized species of UK ants for their CTmax in dry baths (with no boundary layer)
and on hot plates (with a boundary layer). We found that hot plates overestimated the CTmax values of the
different ants, and that this overestimate was larger for taller species. By statistically modelling the thickness of
the thermal boundary layer, and combining with estimates of species height, we were able to correct this
overestimation and eliminate methodological differences. Our study provides two main findings. First, we
provide evidence that organism height is positively related to the bias present in plate-based estimates of CTmax.
Second, we show that a relatively simple statistical model can correct for this bias. By using simple corrections
for boundary layer effects, as we have done here, researchers could open up a new possibility space in the design
and implementation of thermal tolerance assays using plates rather than restrictive dry or water baths.
Description
DATA ACCESSIBILITY STATEMENT : All datasets and scripts are available from doi:10.17632/
fshhh8r5rb.1.
Keywords
Ants, Boundary layer, Dry bath, Hot plate, Physiology, Thermal tolerance, SDG-15: Life on land
Sustainable Development Goals
SDG-15:Life on land
Citation
Corley, R.B., Dawson, W. & Bishop, T.R. 2023, 'A simple method to account for thermal boundary layers during the estimation of CTmax in small ectotherms', Journal of Thermal Biology, vol. 116, art. 103673, pp. 1-9, https://DOI.org/10.1016/j.jtherbio.2023.103673.