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Bees are essential pollinators and understanding their ability to cope with extreme temperature changes is crucial for predicting their resilience to climate change, but studies are limited. We measured the response of the critical thermal maximum (CTMax) to short-term acclimation in foragers of six bee species from the Greek island of Lesvos, which differ in body size, nesting habit, and level of sociality. We calculated the acclimation response ratio as a metric to assess acclimation capacity and tested whether bees’ acclimation capacity was influenced by body size and/or CTMax. We also assessed whether CTMax increases following acute heat exposure simulating a heat wave. Average estimate of CTMax varied among species and increased with body size but did not significantly shift in response to acclimation treatment except in the sweat bee Lasioglossum malachurum. Acclimation capacity averaged 9% among species and it was not significantly associated with body size or CTMax. Similarly, the average CTMax did not increase following acute heat exposure. These results indicate that bees might have limited capacity to enhance heat tolerance via acclimation or in response to prior heat exposure, rendering them physiologically sensitive to rapid temperature changes during extreme weather events. These findings reinforce the idea that insects, like other ectotherms, generally express weak plasticity in CTMax, underscoring the critical role of behavioral thermoregulation for avoidance of extreme temperatures. Conserving and restoring native vegetation can provide bees temporary thermal refuges during extreme weather events.
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Transcriptomics at the thermal limits of an urban introduced lizard
Rapid changes in gene expression can result in physiological plasticity that assists animals in coping with environmental stressors. Increased capacity for physiological plasticity may then facilitate adaptation to stressful habitats like urban heat islands or invasion into novel ranges. Currently, temperature stress is a leading threat to organisms, especially ectotherms. While exposure to changing temperatures is known to shift gene expression patterns in ectothermic animals, many studies are conducted after lengthy acclimation times. However, exposure to thermal stress in nature can occur rapidly. We assessed the capacity for gene expression plasticity in response to a brief exposure to extreme thermal stress in an urban, introduced species, the common wall lizard (Podarcis muralis). Lizards were ramped to their critical thermal maximum (CTmax) or minimum (CTmin) followed by rapid recovery. We used RNA-sequencing to compare the transcriptomes of lizards exposed to CTmax, CTmin, or control conditions using heart, liver, and large intestine tissue. Exposure to heat stress induced a much stronger gene expression response across tissues than cold exposure. In response to heat, there was systemic upregulation of heat shock proteins and stress response pathways. Heat also induced changes in transcription, translation, and metabolic processes but these effects were more tissue specific. Although fewer gene expression changes were observed in response to cold, some genes were upregulated that could be beneficial under cooling stress. Our data suggests gene expression plasticity could facilitate range expansion in this species, but more work is needed to assess the transcriptomic response to temperature stress in nature.
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- Award ID(s):
- 2208809
- PAR ID:
- 10667062
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of Thermal Biology
- Volume:
- 134
- Issue:
- C
- ISSN:
- 0306-4565
- Page Range / eLocation ID:
- 104305
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1016/j.jtherbio.2025.104305
