Ecology

Population

Demography

Gene

Gene flow

Urbanization

Genetic variation

Evolutionary biology

Biology

Sociology

Gene pool

Biological dispersal

Genetics

Genetic diversity

Habitat fragmentation

Habitat

Genetic drift

Population genetics

Molecular Ecology

Evidence is growing that human modification of landscapes has dramatically altered evolutionary processes. In urban population genetic studies, urbanization is typically predicted to act as a barrier that isolates populations of species, leading to increased genetic drift within populations and reduced gene flow between populations. However, urbanization may also facilitate dispersal among populations, leading to higher genetic diversity within, and lower differentiation between, urban populations. We reviewed the literature on nonadaptive urban evolution to evaluate the support for each of these urban fragmentation and facilitation models. In a review of the literature with supporting quantitative analyses of 167 published urban population genetics studies, we found a weak signature of reduced within‐population genetic diversity and no evidence of consistently increased between‐population genetic differentiation associated with urbanization. In addition, we found that urban landscape features act as barriers...

Gene flow and genetic drift in urban environments