Light-Colored Butterflies Fare Better in Warming Climate

Light-colored butterflies and dragonflies are out-competing darker-colored insects in the face of climate change.

In a new study published in Nature Communications, scientists have shown that as the climate warms across Europe, communities of butterflies and dragonflies consist of more light colored species. Darker colored species are retreating northwards to cooler areas, but lighter colored species are also moving their geographical range north as Europe gets warmer.

Such dragonfly species that have made the trek further northwards, and immigrated to Germany, include the Southern Migrant Hawker, the Scarlet Darter and the Dainty Damselfly. This habitat shift has occurred over the last 10 years or so and shows signs of continuing as the climate becomes warmer.

As with lizards and snakes, an insect's color determines how it absorbs energy from the Sun, and is crucial in fuelling its flight and regulating body temperature.

Dark-colored insects, commonly found in cooler climate regions, can absorb more light compared to their light-colored counterparts. In contrast, light-colored species are found in hotter climates because they can better reflect sunlight and prevent overheating.

"For two of the major groups of insects, we have now demonstrated a direct link between climate and insect color, which impact their geographical distribution," Carsten Rahbek, from the Department of Life Sciences at Imperial College London, said in a statement.

To identify this relationship, researchers looked at 366 butterfly species and 107 dragonfly species across Europe, and showed a clear pattern of light-colored insects dominating the warmer south of Europe and darker insects dominating the cooler north. But the warming climate, results showed, caused insects on average to become lighter in color, and darker insects to move towards the cooler Western Europe climates.

"We now know that lighter-colored butterflies and dragonflies are doing better in a warmer world, and we have also demonstrated that the effects of climate change on where species live are not something of the future, but that nature and its ecosystems are changing as we speak," concluded Professor Rahbek, who is also Director of the Center for Macroecology, Evolution and Climate at the University of Copenhagen.