Threshold shifts and developmental temperature impact trade-offs between tolerance and plasticity

Area of Science:

• Physiological ecology
• Climate change biology
• Evolutionary biology

Background:

• Ectotherms face thermal limits, with phenotypic plasticity proposed as a buffer against climate change.
• The tolerance-plasticity trade-off hypothesis suggests higher thermal tolerance correlates with lower plasticity.
• Empirical support for this trade-off is mixed, potentially due to methodological factors like threshold shifts.

Purpose of the Study:

• To investigate the influence of threshold shifts on tolerance-plasticity trade-offs.
• To examine hardening capacity for desiccation tolerance and critical thermal maximum (CT_MAX) in Drosophila species.
• To assess how varying distributions and sensitivities to heat/desiccation stress affect these relationships.

Main Methods:

• Examined threshold shifts in desiccation tolerance and CT_MAX across Drosophila species.
• Assessed hardening capacity under different developmental acclimation temperatures.
• Analyzed trade-off patterns considering varying hardening treatments and developmental temperatures.

Main Results:

• Evidence for threshold shifts was found in both desiccation tolerance and CT_MAX.
• Species with higher heat/desiccation tolerance required longer hardening periods for maximal response.
• Higher heat tolerance was linked to reduced hardening capacity at elevated developmental temperatures.

Conclusions:

• Threshold shifts are crucial for understanding tolerance-plasticity trade-offs in ectotherms.
• Plasticity-tolerance trade-offs are context-dependent, influenced by hardening treatments and developmental temperatures.
• Future studies must incorporate threshold shifts and diverse environmental conditions to accurately assess adaptation potential.