Climate change is putting the fate of ectothermic animals at stake because their body temperature closely tracks environmental temperatures. The ability to adjust thermal limits and preference through acclimation (i.e. acclimation capacity) may compensate for temperature changes. However, although necessary for forecasting the future of ectotherms in a changing climate, knowledge on the factors modulating these plastic responses is fragmentary. For instance, the influence of an animal's sex in driving acclimation capacity has been underappreciated. Here, we present the first systematic review and meta‐analysis on sex differences in thermal acclimation capacity. Using 239 effect sizes from 37 studies and 44 species, we revealed that males and females did not differ significantly in their overall capacity to acclimate their thermal limits and preference. However, in some instances, females expressed significantly greater plastic responses than males. In wild animals, females had a greater heat tolerance plasticity than males. In addition, females had a greater cold tolerance plasticity in terrestrial habitats, but the strength and direction of this sexual dimorphism was associated with the duration of acclimation. We also found a negative correlation between body mass and plasticity. Finally, we demonstrated that the capacity for each sex to adjust their thermal tolerance and preference was remarkably limited. It is important to acknowledge that the above effects were weak and heterogeneous. Hence, in the species we investigated, minor differences in acclimation capacity may not translate into major ecological mismatch between sexes with climate change. Our systematic review also revealed that over 75% of the studies we identified either did not report or confounded the sex of the animals. This under‐reporting may cause to overlook ecologically relevant sex differences in plasticity in ectothermic taxa. We stress the need for further research on sex‐based responses to temperatures. Our synthesis provides additional evidence that the capacity for ectotherms to acclimate to temperatures is limited, and likely insufficient to compensate for the impacts of climate change. A free Plain Language Summary can be found within the Supporting Information of this article.

Understanding the factors affecting thermal tolerance is crucial for predicting the impact climate change will have on ectotherms. However, the role developmental plasticity plays in allowing populations to cope with thermal extremes is poorly understood. Here, we meta‐analyse how thermal tolerance is initially and persistently impacted by early (embryonic and juvenile) thermal environments by using data from 150 experimental studies on 138 ectothermic species. Thermal tolerance only increased by 0.13°C per 1°C change in developmental temperature and substantial variation in plasticity (~36%) was the result of shared evolutionary history and species ecology. Aquatic ectotherms were more than three times as plastic as terrestrial ectotherms. Notably, embryos expressed weaker but more heterogenous plasticity than older life stages, with numerous responses appearing as non‐adaptive. While developmental temperatures did not have persistent effects on thermal tolerance overall, persistent effects were vastly under‐studied, and their direction and magnitude varied with ontogeny. Embryonic stages may represent a critical window of vulnerability to changing environments and we urge researchers to consider early life stages when assessing the climate vulnerability of ectotherms. Overall, our synthesis suggests that developmental changes in thermal tolerance rarely reach levels of perfect compensation and may provide limited benefit in changing environments.

The biological sciences community is increasingly recognizing the value of open, reproducible and transparent research practices for science and society at large. Despite this recognition, many researchers fail to share their data and code publicly. This pattern may arise from knowledge barriers about how to archive data and code, concerns about its reuse, and misaligned career incentives. Here, we define, categorize and discuss barriers to data and code sharing that are relevant to many research fields. We explore how real and perceived barriers might be overcome or reframed in the light of the benefits relative to costs. By elucidating these barriers and the contexts in which they arise, we can take steps to mitigate them and align our actions with the goals of open science, both as individual scientists and as a scientific community.

Extreme temperature events are increasing in frequency and intensity due to climate change. Such events threaten insects, including pollinators, pests and disease vectors. Insect critical thermal limits can be enhanced through acclimation, yet evidence that plasticity aids survival at extreme temperatures is limited. Here, using meta-analyses across 1374 effect sizes, 74 studies and 102 species, we show that thermal limit plasticity is pervasive but generally weak: per 1 °C rise in acclimation temperature, critical thermal maximum increases by 0.09 °C; and per 1 °C decline, critical thermal minimum decreases by 0.15 °C. Moreover, small but significant publication bias suggests that the magnitude of plasticity is marginally overestimated. We find juvenile insects are more plastic than adults, highlighting that physiological responses of insects vary through ontogeny. Overall, we show critical thermal limit plasticity is likely of limited benefit to insects during extreme climatic events, yet we need more studies in under-represented taxa and geographic regions.

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