Urbanization processes modify the characteristics of some plant species

Researchers from the University of Seville and the University of Almeria, along with the Global Urban Evolution Project (GLUE), have studied how urbanization influences the evolutionary dynamics of white clover (Trifolium repens) in 160 cities in 26 countries. Their work, which has just been published by ‘Science’, concludes that this process developed by humans leads to environmental changes that can drive or promote rapid evolutionary adaptations on a global scale.

Urban environments are a new and increasingly dominant feature of terrestrial landscapes, in which more than half of the world's population now resides. Urbanization dramatically transforms ecosystems and is now also believed to significantly alter the evolution of life on Earth.

Specifically, urbanization promotes changes in phenotypic traits in white clover such as the production of hydrogen cyanide, a chemical defense against herbivores, which was lower in urban than in rural environments in 47% of the cities studied. In addition, the genomic study reveals that this evolution in phenotypic traits due to urbanization is explained by adaptive evolution.

Although there are numerous studies on how urbanization affects genetic drift, the effect of urbanization on evolutionary adaptation has received less attention. Adaptation to urban environments could influence the conservation of species, the appearance of pests and diseases, as well as urban planning and society in general. However, so far only studies focused on a single city or a small group of cities have been conducted, so it is not clear whether populations can adapt to urban environments in a similar way in cities around the world. With this objective, the study led by the Global Urban Evolution Project is presented as the largest-scale and best replicated initiative to study the parallel evolution caused by urbanization that has been carried out to date.