Global warming favours light-coloured insects

A warming European climate has led to lighter coloured butterflies and dragonflies out-competing their darker counterparts. Researcher published in Nature Communications has revealed as the climate has warmed, communities of dragonflies and butterflies consist of more lighter coloured species. The darker coloured species are retreating northwards towards cooler areas, but the lighter species are beginning to follow suit. “For two of the major groups of insects, we have now demonstrated a direct link between climate and insect colour, which impact their geographical distribution,” said Carsten Rahbek from the Department of Life Sciences at Imperial College London. “We know that lighter coloured butterflied 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.” The team, which also included researchers from Philipps-University Marburg and the University of Copenhagen, used digital image analysis to identify whether colour lightness was correlated to temperature. They scanned and measured colour values of butterfly and dragonfly wings and bodies, and combined this data with distributional data on where the species can be found in Europe. They studied 366 butterfly species and 107 dragonfly species across Europe, and discovered a clear pattern of light-coloured insects dominating the south of Europe, and darker insects dominating the cooler north areas. To test whether a warming climate had caused any shift, researchers looked at changes in species distribution between 1988 and 2006. Results showed that on average insects were becoming lighter in colour, while darker insects were shifting towards the cooler areas in Western margins of Europe, the Alps and Balkans. “With this research we’ve been able to show that butterfly and dragon species across Europe are distributed according to their ability to regulate heat through their colour variation,” said lead author Dirk Zeuss from Philipps-University Marburg. “Until now we could only watch the massive changes in insect fauna during the last 20 years. Now we have an idea of what could be a strong cause of the changes.” Global warming favours light coloured insects in Europe