Bigger butterflies may cope better with climate change

Butterflies with larger wingspans may be more likely to expand their range at high latitudes because they can fly to new habitats as temperatures rise.

Butterfly species with larger wingspans have expanded their range in high-latitude parts of North America as the climate has warmed, while smaller butterflies and those adapted to cold conditions have tended to decline.

A monarch butterfly on the shores of Lake Superior in Minnesota
Chris Frost/Shutterstock

Vaughn Shirey at Georgetown University in Washington DC and his colleagues built a computational model to analyse data on the presence of 90 butterfly species above 45°N in North America from 1970 to 2019.

The team analysed how shifting monthly minimum temperatures over the past 50 years may have affected the ranges that butterfly species were living in.

The monthly minimum temperatures rose by 0.86°C (1.5°F), on average, across the study region from the 1970s to the 2010s. As temperatures rose, butterfly species with larger wingspans were more likely to spread out into a greater proportion of the study region. But for smaller butterflies, rising temperatures were linked with a decrease in the area over which they were found.

“It seems logical to assume that if species with larger wingspans have the capacity to better travel to new suitable habitats, it gives those species an advantage in a changing climate,” says Yoan Fourcade at the Institute of Ecology and Environmental Sciences in Paris, who wasn’t involved in the study.

Butterflies adapted to warmer temperatures were also found to have dispersed more across the study region than those adapted to colder climates.

The data was collected as part of research and citizen science projects that logged where a species was known to be present, but it is difficult to determine if a species is actually absent in a region where it isn’t reported, says Fourcade.

To work around this, the team’s model predicted which species were really absent using factors such as other species spotted in the area around the same time. Analysing past trends in this way could help conservationists anticipate future changes and protect butterfly populations, says Fourcade.

Climate change has been linked with a decline in some butterfly species, including the monarch butterfly (Danaus plexippus) in North America. But some appear to be adapting to the changing conditions: a study last year found that British butterflies are steadily getting bigger in response to rising temperatures.


bioRxivDOI: 10.1101/2023.04.24.538168

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