Urban Genetic Dynamics in Fragmented Ecosystems

Urbanisation fragments natural habitats into discrete patches, producing a mosaic of green spaces separated by roads, buildings and other impervious surfaces. The resulting genetic dynamics are shaped by altered patterns of reproduction, movement and selection in wildlife populations. Fragmentation tends to reduce gene flow between habitat patches, leading to increased genetic differentiation and potential declines in genetic diversity through drift and inbreeding. At the same time, novel selective pressures in urban environments–such as pollution, noise, artificial light and altered food resources–can drive rapid adaptation in traits linked to metabolism, immunity and behaviour. Research has revealed that species with high dispersal capacity are better able to maintain connectivity across urban landscapes, whereas less mobile taxa often exhibit strong genetic structure and local bottlenecks. Habitat corridors, green roofs and park networks may mitigate fragmentation by facilitating movement, preserving effective population sizes and sustaining evolutionary potential. Globally, understanding urban genetic dynamics informs conservation strategies aimed at enhancing resilience of native species in an ever‐expanding urban world.

Research from Nature Portfolio

Recent studies have examined urban genetic patterns in mammals and birds using high‐resolution genomic tools. Analyses of European rabbit populations along a rural‐to‐urban gradient revealed that urban individuals maintain higher heterozygosity and lower inbreeding coefficients than rural counterparts, despite moderate differentiation driven by environmental barriers rather than geographic distance. Asymmetrical gene flow from rural to urban areas underscores the role of urban centres as genetic sinks or sources depending on landscape context. In an edge‐tolerant songbird, genomic sequencing across an urban island demonstrated a recent contraction in effective population size and subtle spatial structure resulting from limited dispersal in a heavily fragmented tropical metropolis. Even in species able to exploit fragmented habitats, fine‐scale genetic subdivision and loss of rare alleles were detected, emphasising that urbanisation can swiftly impose detectable genomic signatures.

Urban Genetic Dynamics in Fragmented Ecosystems publication trend

The graph below shows the total number of articles in urban genetic dynamics in fragmented ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Gene flow: Movement of genes among populations through dispersal and reproduction, which counteracts differentiation.

Genetic drift: Random changes in allele frequencies, especially pronounced in small or isolated populations.

Effective population size: The number of breeding individuals contributing genes to the next generation, influencing rates of drift.

Heterozygosity: The proportion of individuals carrying two different alleles at a locus, a measure of genetic diversity.

Microsatellite marker: Short tandem repeats in DNA used to assess genetic variation and relatedness.

Single nucleotide polymorphism (SNP): A single base‐pair variation in the genome, used for high‐resolution genetic analyses.

Bottleneck: A recent sharp reduction in population size leading to loss of genetic variation.

Isolation‐by‐distance: A pattern where genetic differentiation increases with geographic distance, due to limited dispersal.

Fixation index (FST): A measure of genetic differentiation between populations, ranging from zero (no differentiation) to one (complete separation).

References

1. Population genetics of the European rabbit along a rural-to-urban gradient. Scientific Reports (2020).
2. Novel genome and genome-wide SNPs reveal early fragmentation effects in an edge-tolerant songbird population across an urbanized tropical metropolis. Scientific Reports (2018).
3. Urban colonization through multiple genetic lenses: The city‐fox phenomenon revisited. Ecology and Evolution (2019).
4. Population genomics of the Anthropocene: urbanization is negatively associated with genome‐wide variation in white‐footed mouse populations. Evolutionary Applications (2016).
5. Dispersal ability predicts spatial genetic structure in native mammals persisting across an urbanization gradient. Evolutionary Applications (2020).