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BERLIN – New research conducted by scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) and the Technische Universität Berlin (TUB) has revealed that the urban environment in Berlin is leaving a genetic signature on the city’s red squirrel (Sciurus vulgaris) populations.
The study, published in the journal Ecology and Evolution, indicates that roads, buildings, and other infrastructure are restricting the movement of these small mammals, leading to subtle genetic differences between squirrels living in different parts of the city.
Study Methodology
Between autumn 2021 and spring 2025, researchers studied 141 squirrels across three distinct locations in Berlin: an inner-city cemetery, a large city park, and a woodland area on the outskirts of the city. These sites were chosen to represent varying degrees of urbanization and connectivity to the wider landscape.
The team generated 135 individual genetic profiles to assess population diversity and connectivity. While squirrels are known to be highly adaptable to urban life-frequently utilizing gardens, parks, and human food sources-the study sought to determine if the fragmented nature of their city habitats was reflected in their genomes.
Key Findings
The genetic analysis revealed that while overall genetic diversity remains high at all three sites, the squirrels from the city park showed more marked differences compared to those in the cemetery and the forest. Lead author Sinah Drenske from the Leibniz-IZW noted, "We do not see any highly isolated populations, but we are already detecting subtle genetic differences that suggest that squirrels cannot move completely freely through the city."
Despite these genetic shifts, the researchers found no clear evidence of negative demographic effects. Catch-recapture data collected over several years showed that survival probabilities remained similar across all three study sites.
Importance of Urban Planning
Stephanie Kramer-Schadt, co-author from the Leibniz-IZW and TUB, emphasized the importance of connectivity for urban wildlife. "The results show that Berlin’s squirrels exhibit a high level of genetic diversity and that there is currently no evidence of significant inbreeding," she said. "Should connectivity between urban habitats continue to decline in future, this could lead to a further reduction in genetic exchange."
The study suggests that the preservation and creation of green spaces and tree-lined corridors are essential for maintaining genetic exchange among urban wildlife populations. Experts recommend that future urban planning should prioritize wildlife-friendly infrastructure to support biodiversity in densely developed cities.
Source: Mirage News
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