European City Life: Rewriting Insect DNA Evolution

Cities are known to shape the evolution of wildlife within them, but according to a study of European cities published in the journal Proceedings of the Royal Society B: Biological Sciences, this is not a one-off event. Rather than a single urban genotype of a species spreading from one place to another, scientists found that evolution often starts from scratch, creating distinct genotypes in different cities. Butterflies and moths Researchers looked at the impact of cities on two types of insects: the Small Heath butterfly (Coenonympha pamphilus) and the Latticed Heath moth (Chiasmia clathrata). They took samples from dozens of sites across Europe, and at almost every location they collected insects from both the city and nearby rural areas. This allowed them to compare city and countryside varieties. To see how they may differ, the team analyzed the DNA of over six hundred insects. Reading their entire genomes would have been too expensive and time-consuming, so they used a technique called ddRADseq that acts like a high-speed scanner and takes snapshots of the DNA at specific points. Evolution in the concrete jungle The researchers found that in nearly all the cities studied, the urban populations were most closely related to the neighboring rural populations, rather than to city types in other countries. This was the same for both insect species, which suggests the urban version of these insects is being invented repeatedly by local populations rather than spreading from a single source. However, the two insects showed a major difference in how their genetic diversity is spread across the continent. Because the butterflies don't travel much, the city version in one country, such as Belgium, looks genetically different from the city version in Italy. In contrast, because the moths travel and mix widely, their DNA stays mostly the same across the entire continent, even as they adapt to their local urban environment. The study authors also discovered that while cities do influence wildlife, they are not the most powerful factors. When looking at genetic markers, the team found that the local climate, such as average temperatures and length of the growing season, has a larger impact on insect DNA than the urban environment. While this research shows how cities are forcing some insects to adapt, the scientists caution that we cannot apply these findings to every animal. As they note in their paper, "Our study adds diversity to the reported patterns of genetic population structure in the urban evolutionary ecology context and highlights that caution is needed when generalizing results based on a few species." © 2026 Science X Network