Urbanization creates new challenges for species—some adapt or move, others die out. Scientists say urbanization-induced evolution, which alters the way ecosystems work, will have global impacts. For example, it could reduce the ability of plant seeds to disperse, encourage infectious diseases, and even change the migration patterns of some species. Installing galvanized electricity pylons has created new habitats suitable for plant species that tolerate high levels of zinc in their surroundings. The evolutionary clock has apparently been sped up by human activity.