Mosquito thermal tolerance is remarkably constrained across a large climatic range

Area of Science:

• Ecology
• Evolutionary Biology
• Climate Change Biology

Background:

• Understanding how mosquito species respond to rapid climate warming is crucial for predicting their future distributions and impacts on biodiversity and human health.
• Mosquitoes are significant vectors of disease, making their adaptive capacity to changing climates a critical area of research.

Approach:

• A common garden experiment was conducted to assess the adaptive potential of the mosquito species *Aedes sierrensis* across a wide climatic gradient.
• The study measured the thermal limits of various mosquito life history traits to evaluate population-level variation in heat tolerance.

Key Points:

• Despite originating from diverse thermal environments spanning over 1,200 km, *Aedes sierrensis* populations exhibited minimal variation (<1°C) in upper thermal tolerance limits for most fitness traits.
• Local thermal adaptation was observed for pupal development rate, with higher thermal limits in populations from warmer source environments.
• Estimated upper thermal limits are frequently surpassed by current environmental temperatures across much of the species' range.

Conclusions:

• The limited adaptive potential suggests that mosquito thermal tolerance may not evolve rapidly enough to keep pace with climate warming.
• Strategies such as diapause, phenological shifts, and behavioral thermoregulation are likely essential for mosquito persistence in warming climates.
• These findings have implications for predicting future mosquito distributions and the associated risks of vector-borne diseases.