City butterflies keep flying for longer

A new study led by VUB biologist Thomas Merckx shows that because of the warmer urban environment in which they live, butterflies and moths display a longer flight season than those in the surrounding countryside. The experiments he and colleagues conducted demonstrate for the first time that urban populations are evolutionarily adapted to start their overwintering state later in the year. "This result shows that there are urban populations of butterflies and moths that have managed to adapt evolutionarily to the warmer, urban climate," says Merckx, who started the Global Change Biology group within VUB's Department of Biology on the 1^st of December. Cities are often warmer than surrounding areas. This creates a longer growing season for insects, when it is warm enough for them to reproduce. Many insects, including several butterflies and moths, benefit from a longer growing season and some even manage to produce an extra generation. Genetic adaptations can help, says Merckx: "Because cities provide extreme environments for many organisms, such evolution can be very rapid: genetic adaptations can take place in as little as five to ten years.