British and Spanish Butterflies Use Different Strategies to Control Their Body Temperature

Climate change is affecting the natural world in many ways, but some species are more resilient than others. A recent study by the University of Cambridge and the Institut de Biologia Evolutiva in Barcelona reveals an intriguing discovery about butterfly populations in Catalonia, northern Spain.

These butterflies exhibit a superior ability to regulate their body temperature compared to their British counterparts. By basking in the sunshine, they have developed efficient methods to warm their bodies and adapt to varying environmental conditions. However, this adaptation is not without its challenges.

The rising global temperatures due to climate change may put these adept Spanish butterflies at a greater risk of extinction. Their reliance on finding warm microclimates is both a blessing and a curse, showcasing nature's delicate balance.

Temperature Regulation Mastery

(Photo : MIGUEL ALVAREZ/AFP via Getty Images)

Butterflies are ectotherms, meaning they depend on external sources of heat to maintain their body temperature. This is crucial for their survival, as they need to be warm enough to fly, feed, mate, and avoid predators.

Different species of butterflies have different strategies to regulate their body temperature, such as changing their wing posture, color, or location. Some species are more proficient at this than others, depending on their evolutionary history and geographical distribution.

The researchers compared the thermal behavior of two closely related butterfly species: the speckled wood (Pararge aegeria) and the wall brown (Lasiommata megera).

These species are found in both the UK and Spain, but they have diverged in their thermal preferences and adaptations.

The researchers measured the body temperature and wing posture of hundreds of butterflies in the field, and also conducted experiments in the laboratory to test their thermal tolerance and performance.

The results showed that the Spanish butterflies of both species were better at regulating their body temperature than their British cousins.

They were able to achieve higher and more stable body temperatures by basking in the sun, using their wings as solar panels.

They also had a higher thermal tolerance, meaning they could withstand higher temperatures without losing their ability to fly. The researchers attributed this to the fact that the Spanish butterflies live in a more variable and unpredictable climate, where they have to cope with both cold and hot conditions.

The British butterflies, on the other hand, live in a more stable and mild climate, where they have less need to adjust their body temperature.

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The British Counterpart's Struggle

The study also revealed that the British butterflies of both species were less adept at regulating their body temperature. Unlike their Spanish relatives who seek warmth, they tended towards heat-avoiding behavior.

They often rested in the shade, or oriented their wings perpendicular to the sun, reducing their exposure to solar radiation. They also had a lower thermal tolerance, meaning they could not cope with high temperatures as well as the Spanish butterflies.

The researchers suggested that this was because the British butterflies have evolved to avoid overheating, as they live in a more humid and cloudy environment, where the risk of dehydration is higher.

However, this natural instinct puts them at a disadvantage amidst global warming trends, where adaptability is key for survival.

The researchers predicted that the British butterflies would face more challenges in the future, as they would have to cope with higher and more variable temperatures, as well as changes in their habitat and food availability.

They also warned that the Spanish butterflies, despite their superior thermal regulation skills, would not be immune to the effects of climate change.

They argued that the Spanish butterflies may have reached their limit of adaptation, and that further increases in temperature may push them beyond their thermal threshold, leading to population declines or extinctions.

The study underscores an urgent need for comprehensive conservation strategies that consider these inherent biological differences among species.

It serves as a reminder that climate change impacts are intricate and multifaceted, requiring nuanced approaches for mitigation and adaptation.

The researchers also highlighted the importance of preserving the diversity and complexity of natural habitats, where microclimates can provide refuge and opportunities for species to cope with changing conditions.

They concluded that the fate of these butterflies, and many other species, depends on how we respond to the global environmental crisis.

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