• Wed. Feb 28th, 2024

Strange weather keeps butterflies on the move longer

Strange weather keeps butterflies on the move longer

According to a new study, erratic hot and cold days can extend the active period of moths and butterflies by a month.

As Earth’s climate continues to warm due to greenhouse gas emissions, extreme and unusual weather events are becoming more common. But by definition, predicting and analyzing what constitutes an anomaly is difficult.

Scientists say museum specimens can help. For the new study, the first of its kind, the researchers used natural history models. “The results were not what we expected,” says Robert Guralnick, curator of biodiversity informatics at the Florida Museum of Natural History and lead author of the study. Communications Biology.

Most studies view climate change and its consequences through the periscope of average temperature rise. As temperatures rise over time, plants and animals in a particular region become active in early spring, then become dormant until fall, slowly shifting their ranges to adapt to the climate best suited for survival.

Erratic climate adds a layer of complexity to these patterns, with unknown consequences that place an opaque screen in front of scientists trying to predict the future of global ecosystems.

“There were indications in the scientific literature that climate anomalies could have cumulative effects on ecosystems, but there was nothing that directly addressed this question at a broad scale,” says Guralnick.

He explains that this omission is primarily due to a lack of sufficient data. Although climate data has been reliably collected in many parts of the world for more than a century, records documenting the location and activity of organisms are hard to come by.

Natural history museums are considered a potential solution. The oldest museums have collected specimens for hundreds of years, and recent efforts to digitize the collections have made their contents widely available. But digital museum records have their own flaws and shortcomings.

In 2022, co-author Michael Belitz built a dataset of moths and butterflies from museum collections to chart a course for other researchers hoping to use similar data. The result was a comprehensive instruction manual on how to collect, organize, and analyze data from natural history specimens.

With this powerful resource at their disposal, Belitz and his colleagues wanted to see if they could detect a signal from divergent weather patterns. Limiting their analyzes to the eastern United States, the authors used records of 139 moths and butterflies collected from 1940 to 2010.

Their results were unequivocal: Abnormally warm and cold climates over the past few decades have significantly altered insect activity to a greater degree than the average increase in global temperatures.

The location and timing of extreme weather events influenced how insects responded. At higher latitudes, the warm days of winter have led to moths and butterflies becoming active in early spring. Abnormally cool days kept insects active longer at all latitudes, with a combination of abnormally high and low temperatures having the strongest effect.

“If you have unusually cold and hot days in a row, that limits the insect’s ability to perform at peak performance,” Guralnick says. “If the cold doesn’t kill you, it slows you down, and it might force the insect into a topper. Insects can recover very quickly from a cold snap and live longer as a direct result of the sudden drop in temperature.

Insects being active for a long time may seem like a good thing at first. But far from being a remedy for the negative effects of climate change, co-author Lindsey Campbell, who studies mosquitoes, points out that longer or altered insect lifespans mean more opportunities for pathogen transmission.

“There is a correlation between El Niño and Rift Valley fever outbreaks in East Africa, with anecdotal observations showing unusually warm, hot or dry springs, followed by heavy rains associated with increased outbreaks,” says Campbell. Assistant Professor at the University of Florida.

Long-term ecosystem sustainability also depends on the coordinated functioning of its components, and plants may not respond to extreme climates in the same way as insects. If moths and butterflies take off too early, they encounter plants that have not yet produced leaves or flowers and expend energy in a futile search for food.

As the basis for ‘extreme’ is constantly changing, it is unclear whether insects can keep up with the changes.

“As average temperatures and climate change increase, an organism’s immune system is going to decline rapidly,” says Guralnick. “Today’s extreme events are going to become more extreme in the future, and at some point, the capacity to buffer against these changes will reach its limit.”

The study was indirectly supported by the National Science Foundation and the National Institute of Food and Agriculture.

Source: University of Florida

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