Climate Change Could Diminish Butterfly Spots, Study Finds

Some butterflies could lose their spots as a result of climate change, new research shows.

Scientists from the University of Exeter found that Meadow Brown butterflies have fewer spots if they develop in warmer weather.

The change, which helps them blend in to a browner landscape, means that some species might not move north but stay where they are.

Females that developed at 11° C (51.80 °F) had six spots on average, whereas those that developed at 15° C (59.00 °F) had just three.

This means that if temperatures around the world continue to rise, this species of butterfly could become less spotty – possibly changing the way it camouflages itself and stays safe from predators.

Professor Richard French-Constant, from the University of Exeter’s Centre for Ecology and Conservation, said: “Meadow Browns always have large ‘eyespots’ on their forewings, probably for startling predators.

“They also have smaller spots on their hindwings, probably useful for camouflage when a butterfly is resting.

“Our findings show that fewer of these hindwing spots appear when females experience higher temperatures during their pupal stage – the stage before they emerge as a butterfly.”

This could however be an evolutionary choice, Professor Ffrench-Constant explained, with butterflies adapting to their surroundings amid climate change.

“Our findings suggest that butterflies adapt their camouflage based on the conditions.

“So, with fewer spots, they may be harder to spot on dry, brown grass – something that would be more common in hotter weather.”

The team from the University of Exeter discovered that temperatures did not affect male Meadow Browns’ number of spots in the same way as females.

“This is possibly because their spots are important for sexual selection, or attracting females,” Professor Ffrench-Constant said.

The new study, published in the journal Ecology and Evolution, has challenged long-held scientific views about why these butterflies have varying number of spots – discovering that eyespot variation is caused by a butterfly’s thermal plasticity, the ability to react to changing temperatures.

The team therefore predicts that butterfly spotting will decrease year on year as our planet warms.

Professor Ffrench-Constant said: “This is an unexpected consequence of climate change.

“We tend to think about species moving north – not changing appearance.”

The University of Exeter conducted its study by analyzing male and female butterflies from Cornwall throughout their flight season – which typically starts around April – as well as historical collections from Eton and Buckingham.

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