Interactions between developmental and adult acclimation have distinct consequences for heat tolerance and heat stress recovery

Abstract

Developmental and adult thermal acclimation can have distinct, even opposite, effects on adult heat resistance in ectotherms. Yet, their relative contribution to heat-hardiness of ectotherms remains unclear despite the broad ecological implications thereof. Furthermore, the deterministic relationship between heat-knockdown and recovery from heat stress is poorly understood but significant for establishing causal links between climate variability and population dynamics. Here, using D. melanogaster in a full-factorial experimental design, we assess flies heat-tolerance in static stress assays, and document how developmental and adult acclimation interact with a distinct pattern to promote survival to heat-stress in adults. We show that warmer adult acclimation is the initial factor enhancing survival to constant stressful high temperatures in flies, but also that the interaction between adult and developmental acclimation becomes gradually more important to ensure survival as the stress persists. This provides an important framework revealing the dynamic interplay between these two forms of acclimation, that ultimately enhance thermal tolerance as a function of stress duration. Furthermore, by investigating recovery rates post-stress, we also show that the process of heat-hardening and recovery post heat knockdown are likely to be based on set of (at least partially) divergent mechanisms. This could bear ecological significance as a tradeoff may exist between increasing thermal tolerance and maximizing recovery rates post-stress, constraining population responses when exposed to variable and stressful climatic conditions.

Exploring the Connection between Autophagy and Heat-Stress Tolerance in Drosophila melanogaster

“…This means that the heathardier flies (that took longer to lose their righting response), were not necessarily the ones to recover faster from heat knockdown, independently of treatments. This also suggest heattolerance and stress-recovery to be at least based on partly different set of mechanisms (Willot et al, 2021). Overall, our results thus further bridge the link between TOR inhibition, autophagy induction, and heat-tolerance in D. melanogaster.…”

“…The copyright holder for this preprint this version posted December 10, 2021. ; https://doi.org/10.1101/2021.12.09.471892 doi: bioRxiv preprint 12 (Willot et al, 2021). Overall, our results thus further bridge the link between TOR inhibition, autophagy induction, and heat-tolerance in D. melanogaster.…”

Warming During Embryogenesis Induces a Lasting Transcriptomic Signature in Fishes

“…Recent work has demonstrated that mosquitofish born in the more thermally variable spring environment have a greater capacity to acclimate their metabolic processes than mosquitofish from the more thermally stable summer conditions (Seebacher et al, 2014). Finally, studies of fruit flies (Drosophila melanogaster) have shown that heat tolerance is influenced not just by acclimation temperature, but by an interaction between acclimation temperature and embryonic temperature, further supporting the role of the early-life thermal environment in dictating an individual's response to future temperature challenges (Willot et al, 2021).…”

The role of body mass in limiting post heat‐coma recovery ability in terrestrial ectotherms

“…In ectotherms, body mass represents one of the critical traits for thermal adaptation and physical heat exchange (Bergmann, 1848; Campbell & Norman, 1998), with thermal inertia playing a key role in both heat gain and loss which may ultimately affect recovery ability. The recovery ability after heat‐coma in ectotherms remains nonetheless unclear, particularly the relationship between heat‐coma recovery and body mass (e.g., Bozinovic et al, 2011; Willot et al, 2021). As extreme hot days and pulsed, short‐term heatwaves are becoming more frequent under climate change (Lee et al, 2021; Rahmstorf & Coumou, 2011), the recovery ability of organisms after extreme heat events could be a key trait for survival and act as a precursor to adapt to novel environmental conditions (Angilletta Jr, 2009).…”

“…The recovery ability after heat-coma in ectotherms remains nonetheless unclear, particularly the relationship between heat-coma recovery and body mass (e.g., Bozinovic et al, 2011;Willot et al, 2021).…”