Butterflies most at risk of extinction identified

By Alice Clifford via SWNS

Small-winged and lighter-colored butterflies are likely to be most at risk of extinction due to climate change, according to new research.

Wing length and wing color of tropical butterflies all influence their ability to withstand rising temperatures.

While darker and larger winged butterflies are better at coping with increasing temperatures, small and lighter ones do not handle the change as well.

The Lycaenidae family, which contains over 6,000 species of butterflies and lives mainly in the tropics, are particularly vulnerable.

Butterflies rely on the sun’s warmth to give them the energy they need to function.

They use strategies to maintain a balanced body temperature against changing air temperatures.

Two key ones are thermal buffering and thermal tolerance.

Thermal buffering refers to a butterfly’s ability to fly to shady spots or angle their wings away from the sun.

But when this is not possible, or temperatures get too hot, species have to rely on physiological mechanisms.

One important strategy is thermal tolerance, where butterflies produce heat shock proteins that help them withstand higher temperatures.

Both these are vital to help them cope with climate change.

To find out which species coped the best, researchers studied tropical butterflies to see how well they carried out these strategies.

To do this they collected data from multiple habitats in Panama.

Ecologists took the temperature of over 1,000 butterflies and compared each one’s temperature to that of the surrounding air or the plant they were perched on.

This showed their ability to maintain a steady body temperature against fluctuating air temperatures.

They then did a second experiment to assess how well they can withstand extreme temperatures they may experience during a heat wave.

To do this they placed butterflies in glass jars and put them in a water bath where the temperature was steadily increased.

They then determined at what temperature the butterflies could no longer function.

Butterflies with large wings tended to be better at thermal buffering but had less thermal tolerance than smaller butterflies.

Darker-winged butterflies were also better at thermal buffering than paler-winged butterflies.

They could also tolerate higher temperatures better than the light butterflies.

Those that were good at thermal buffering were less good at thermal tolerance and vice versa.

This observation led scientists to suggest that tropical butterflies have evolved to cope with temperature changes using one of these strategies at the expense of the other.

Butterflies from the Lycaenidae family, which have small, bright, and often iridescent, wings had the poorest thermal buffering and low thermal tolerance.

The researchers fear that if temperatures continue to rise at the current rate and forests continue to be cut down, many species in this family could be lost.

Lead author Esme Ashe-Jepson, a Ph.D. student at Cambridge’s Department of Zoology, said: “Butterflies with physical characteristics that may help them to avoid the sun’s heat, like having large wings that enable them to fly quickly into shade, rarely experience high temperatures, and so have not evolved to cope with them.

“On the other hand, species that can cope with higher temperatures physiologically have experienced less selective pressure to evolve heat-avoiding behaviors.

“As temperatures continue to rise, and forest fragments get smaller and further apart because of deforestation, butterflies which rely on their surroundings to avoid high temperatures may not be able to travel between forest fragments, or cope with increasingly common heatwaves.”

But they warn that these stronger butterflies could still be at risk if there was a sudden heatwave or if cool microclimates were lost through deforestation.

She added: “Ultimately all insects, including butterflies, the world over are likely to be affected by climate change.

“Adaptation to climate change is complex and can be impacted by other factors such as habitat destruction. We need to address these two global challenges together.”

Senior author Dr. Greg Lamarre, from the Czech Academy of Science and research associate at the Smithsonian Tropical Research Institute in Panama, added: “Worldwide, most entomologists are observing drastic declines in insect biodiversity.

“Understanding the causes and consequences of insect decline has become an important goal in ecology, particularly in the tropics, where most of the terrestrial diversity occurs.”

The study was published in the Journal of Animal Ecology.