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Some butterflies are better at regulating their body temperature than others

A study recently published in the Journal of Animal Ecology highlights how different butterfly populations adapt to their environments and the risks they face from climate change. 

Researchers from the University of Cambridge and the Institut de Biologia Evolutiva (IBE) in Barcelona focused on butterfly populations in Catalonia, northern Spain, and compared them to their counterparts in the UK. They found significant differences in how these butterflies regulate their body temperature, a critical factor for survival in changing climates.

Heat-avoiding behavior 

Butterflies in warmer climates like Catalonia have developed efficient ways to regulate their body temperature, primarily by basking in the sun. By contrast, British butterflies adapt to cooler temperatures by seeking warm microclimates. However, with global temperatures on the rise, both populations are beginning to display heat-avoiding behavior. 

While British butterflies might initially benefit from warmer climates, Spanish butterflies face a greater risk of extinction if they cannot adapt quickly enough to the rising temperatures.

Focus of the study 

Eric Toro-Delgado from IBE, lead author of the study, explained the motivation behind the research: “The first study in the UK showed that butterflies are pretty good at regulating their body temperature in this cooler climate, but we wanted to see whether butterflies in a warmer climate, such as Spain, are doing anything differently.” 

“In Spain, butterflies spend much more time at their optimum temperature since it’s warmer, but there’s also a greater risk of overheating,” added senior author Andrew Bladon from Cambridge’s Department of Zoology.

Climate adaptation 

The study, which mirrors a 2020 UK research project by some of the same scientists, involved measuring the body, air, and perch temperatures of nearly 800 adult butterflies across 23 species in Catalonia. 

The researchers aimed to understand whether adaptations observed in Spanish butterflies could indicate how British butterflies might need to adapt in response to climate change.

Key findings 

The findings revealed that Catalan butterflies are better at regulating their body temperature compared to British butterflies. Both populations switch from heat-seeking to heat-avoiding behavior at air temperatures around 22°C. 

However, British butterflies rely more on microclimates for thermoregulation, while Catalan butterflies have a wider range of thermal environments to choose from.

Habitat and biodiversity loss 

The researchers also noted that habitat and biodiversity loss, particularly in the UK, are significant threats to butterflies. Diverse habitats provide a variety of microclimates that can help butterflies maintain their preferred temperatures. 

Bladon emphasized the importance of creating biodiverse environments: “If we can provide them with field margins, biodiverse road verges, more wildflowers, and longer grass, butterflies can more easily move through the landscape.”

Body temperature regulation 

Despite the current ability of Catalan butterflies to thermoregulate effectively, the rising global temperatures pose a significant threat, as Spain is already experiencing warmer climates. The study found that wing size, which was a factor in regulating body temperature in UK butterflies, did not have the same relevance in Spain, where avoiding heat is more critical.

“Because of rising global temperatures, the UK’s climate is becoming a little bit more like Spain, so climate change may benefit British butterflies in the short term,” Bladon explained. However, both populations show signs of heat avoidance, with Catalan butterflies facing a higher risk due to their proximity to their thermal optimum.

Study implications 

The study concludes that in addition to rising temperatures, extreme weather events like droughts and heatwaves, exacerbated by climate change, pose risks to both adult butterflies and their caterpillars. 

“Climate change and biodiversity loss go hand-in-hand, and we urgently need to address both if we’re going to protect important species like butterflies,” Toro-Delgado warned. This research underscores the intricate relationship between climate change, biodiversity, and the survival of vital species like butterflies.

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