An international team of scientists have discovered that the coloration of butterflies and dragonflies can affect their geographic range, a process likely influenced at least partially by ongoing climate change. The 18-year study tracked the locations of 366 butterfly species and 107 dragonfly species across Europe.
Lighter Bugs in Warmer Regions
The study concluded definitively, if perhaps unsurprisingly, that lighter-colored species are more abundant in warmer, southern European climates. Conversely, darker-colored species were able to thrive better in cooler, northern and mountainous environments.
Insects’ coloration, like that of lizards and snakes, plays a crucial role in how much energy they can absorb from the sun and how they regulate their body temperatures. Darker insects absorb more sunlight energy, while lighter insects reflect it. However, because coloration can also have other important purposes, such as camouflage, scientists were surprised to find such a distinct variation between northern and southern species.
“When studying biodiversity, we lack general rules about why certain species occur where they do,” the study’s lead author, Dirk Zeuss from Phillips-University Marburg, Germany, said in a statement. “With this research, we’ve been able to show that butterfly and dragonfly species across Europe are distributed according to their ability to regulate heat through their color variation. [Previously] we could only watch the massive changes in the insect fauna […] Now we have an idea of what could be a strong cause of the changes.
Two Decades of Study
From 1988 to 2006, Zeuss and colleagues from the University of Copenhagen and Imperial College London, examined butterfly and dragonfly species distribution throughout Europe. Their research showed a clear pattern of lighter insects in the south and darker insects in the north, most likely a geographical and biological response to climate change.
The scientists noted that several Mediterranean dragonfly species, including the Scarlet Darter, the excellently-named Dainty Damselfly, and the now-appropriately named Migrant Hawker expanded their northern range and eventually immigrated almost their entire species into Germany. Mediterranean butterfly species such as the Southern Small White have also immigrated into Germany over the past decade, and continue to gradually move their species northward.
While previous research suggested that climate change may have impacted insect populations and species distribution, this new study shows a direct link between climate change and insects.
“For two of the major groups of insects, we have now demonstrated a direct link between climate, insect color, and habitat preference,” stated Carsten Rahbek, one of the study’s co-authors, Director of the Center for Macroecology, Evolution, and Climate at the University of Copenhangen, and professor at Imperial College, London. “We know that lighter-colored [insects] 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.
The research group’s complete findings were published in Nature Communications.