Context:
Climate change is leading to an increase in mean temperatures as well as a higher frequency of extreme thermal events. Ectotherms are particularly vulnerable to such changes, as their capacity to cope with heat waves and increasing temperatures is often limited (Gunderson & Stillman, 2015; Barley et al., 2021).
Thermal death time (TDT) framework has been developed to better understand the combined effects of temperature and duration of exposure to high temperatures on individual physiology and survival (Jørgensen et al., 2021; Ørsted, Jørgensen, & Overgaard, 2022). TDT framework is based on the idea that temperature-related injuries increase exponentially when critical body temperature is exceeded and internal homeostasis can no longer compensate for these injuries. The duration of heat exposure and inclusion of post-exposure recovery mechanisms allows the associated mortality to be quantified (Ørsted et al., 2024; Ørsted et al., 2026).
However, TDT framework is yet to be included in population dynamic models that incorporate individual physiology, such as physiologically structured models (De Roos et al., 2008), to better understand individual-, population- and community-level responses to extreme thermal events.
Internship objective:
The aim of this internship is to explore the integration of TDT framework into population dynamics models. Starting from existing models of temperature effects in simple size-structured food webs (Dijoux et al., 2023; Dijoux et al., 2024), the intern will develop and explore a simple consumer-resource model incorporating seasonality and additional mortality effects beyond critical temperatures. Depending on their skills and interests, the intern may then:
• integrate mechanisms of repair of temperature-induced damage;
• extend the model to more complex communities.
Candidate profile:
We are looking for a student with:
– interest in population and community dynamics, physiology, and thermal ecology;
– interest in statistical data analysis and modeling in R or other languages (e.g. Python/C++);
– rigor, autonomy, and strong writing skills;
– good command of English, as the working environment is international.
Internship location:
University of South Bohemia in České Budějovice
Faculty of Science — Department of Ecosystem Biology
Aquatic Ecology Laboratory
370 05 České Budějovice, Czech Republic
Supervisors:
Souleyman Bakker, Postdoctoral Researcher (sbakker@prf.jcu.cz)
David Boukal, Laboratory Head (dboukal@prf.jcu.cz)
Internship period:
Second semester of the 2026–2027 academic year (starting date is flexible)
To apply, please send your CV and cover letter to the following address: sbakker@prf.jcu.cz.
Applications will be reviewed this autumn.
References:
Barley, J. M., Cheng, B. S., Sasaki, M., Gignoux-Wolfsohn, S., Hays, C. G., Putnam, A. B. et al. (2021). Limited plasticity in thermally tolerant ectotherm populations: evidence for a trade-off. Proceedings of the Royal Society B: Biological Sciences, 288(1958), 20210765.
De Roos, A. M., Schellekens, T., Van Kooten, T., Van De Wolfshaar, K., Claessen, D., & Persson, L. (2008). Simplifying a physiologically structured population model to a stage-structured biomass model. Theor Popul Biol, 73(1), 47-62.
Dijoux, S., Smalås, A., Primicerio, R., & Boukal, D. S. (2024). Differences in Tri-Trophic Community Responses to Temperature-Dependent Vital Rates, Thermal Niche Mismatches and Temperature-Size Rule. Ecol Lett, 27(11), e70022.
Dijoux, S., Pichon, N. A., Sentis, A., & Boukal, D. S. (2023). Body size and trophic position determine the outcomes of species invasions along temperature and productivity gradients. Ecology Letters, 27(1).
Gunderson, A. R., & Stillman, J. H. (2015). Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming. Proceedings of the Royal Society B: Biological Sciences, 282(1808), 20150401.
Jørgensen, L. B., Malte, H., Ørsted, M., Klahn, N. A., & Overgaard, J. (2021). A unifying model to estimate thermal tolerance limits in ectotherms across static, dynamic and fluctuating exposures to thermal stress. Scientific Reports, 11(1), 12840.
Ørsted, M., Jørgensen, L. B., Hůla, P., & Overgaard, J. (2026). Integrating Physiological Rates of Thermal Stress and Repair Predicts Heat Failure During Temperature Fluctuations. Ecol Lett, 29(5), e70398.
Ørsted, M., Jørgensen, L. B., & Overgaard, J. (2022). Finding the right thermal limit: a framework to reconcile ecological, physiological and methodological aspects of CTmax in ectotherms. J Exp Biol, 225(19), jeb244514.
Ørsted, M., Willot, Q., Olsen, A. K., Kongsgaard, V., & Overgaard, J. (2024). Thermal limits of survival and reproduction depend on stress duration: A case study of Drosophila suzukii. Ecology Letters, 27(3).
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