Urban butterflies under threat of extinction

According to an EPFL study, butterflies living in urban areas face the threat of consanguinity and potential extinction. The research drew on the fields of genetics and urban development to quantify the trend across an entire city. "Our research illustrates what is probably a widespread phenomenon: a drastic reduction in biodiversity in urban areas. We were able to quantify this trend and show that it's a problem that needs to be taken seriously," says Estelle Rochat, a PhD student at EPFL's Laboratory of Geographic Information Systems (LASIG). Looking at the densely populated Marseille region, Rochat measured the effect of urbanization on the genetic diversity of a particular species of butterfly, the small white ( Pieris rapae, see on the left ) . She found that diversity fell by 60-80% in areas with a high urbanization rate, which means they have over 56% impervious land cover (i.e., land that has been developed with roads, buildings and other structures). In less dense neighborhoods, with between 3% and 13% impervious land cover, the loss in diversity was just 16-24%.