Research shows that cities affect different bee species in opposite ways, even when they’re closely related. According to Gram Research analysis of two specialized bee species, one experienced genetic decline and population loss in urban areas while the other remained stable, despite both showing signs of genetic adaptation to city living. The key finding: how bees respond to cities depends on their specific ecological traits and the particular landscape features available, not simply on how urban an area is.
Scientists studied two types of specialized bees to understand how city living affects their genes. According to Gram Research analysis, the bees responded to urban environments in surprisingly different ways, even though they’re closely related. One bee species lost genetic diversity and declined in numbers, while the other stayed stable. The key finding: cities don’t affect all bees the same way. Instead, how bees respond depends on their specific traits, like how far they travel and what plants they need. This research shows that understanding urban evolution requires looking at each species’ unique lifestyle, not just measuring how “urban” an area is.
Key Statistics
A 2026 research article analyzing whole-genome sequencing of two solitary bee species found that Andrena florea showed lower genetic diversity and recent population decline in urban areas, while Andrena vaga maintained higher diversity and demographic stability across the same urban gradient.
Research on two related bee species revealed that genetic diversity was associated with species-specific landscape features—edge density for one species and semi-natural habitat for the other—rather than with urban intensity alone.
A genomic study of urban bees identified loci associated with urban intensity and detected genomic regions showing patterns consistent with positive selection, indicating that both species were genetically adapting to city conditions despite divergent demographic trajectories.
The Quick Take
- What they studied: How living in cities changes the genetic makeup of two closely related bee species that specialize in eating pollen from specific plants
- Who participated: Two species of solitary bees (Andrena florea and Andrena vaga) collected from areas with different levels of urban development, from rural to heavily urban
- Key finding: The two bee species showed opposite genetic patterns in cities: one lost genetic diversity and declined in population, while the other maintained stable diversity and population numbers. Both species showed signs of adapting to urban conditions, but through different genetic changes.
- What it means for you: Cities affect different bee species in different ways. Protecting bees in urban areas requires understanding each species’ specific needs rather than applying one-size-fits-all conservation strategies. This research helps scientists predict which bees might struggle in cities and which might adapt.
The Research Details
Researchers collected bees from areas ranging from completely rural to heavily urban and analyzed their complete genetic code using modern DNA sequencing technology. They looked at two related bee species that have different lifestyles: one travels farther to find food, and one stays closer to home. The scientists examined how genetic diversity changed across the urban gradient and identified specific genes that appeared to be changing in response to city living.
They used two main analytical approaches. First, they looked at neutral genetic patterns—the background genetic variation that doesn’t directly affect survival. Second, they searched for specific genes showing signs of natural selection, meaning genes that help bees survive better in cities were becoming more common. This two-pronged approach revealed whether cities were simply reducing genetic diversity or actively selecting for certain traits.
The researchers also mapped landscape features like green spaces, fragmented habitats, and developed areas to understand which environmental factors most strongly influenced genetic changes in each bee species.
This research approach is important because previous studies often assumed all species respond to cities the same way. By comparing two closely related species with different ecological needs, the scientists could separate universal urban effects from species-specific responses. This helps us understand that urban evolution is complex and depends on each species’ unique characteristics.
This study uses whole-genome sequencing, which is the gold standard for understanding genetic changes. The researchers integrated multiple analytical methods (population genetics, landscape genomics, and functional annotation) to build a comprehensive picture. The study was published in Molecular Ecology, a respected peer-reviewed journal. However, the exact sample size of individual bees wasn’t specified in the abstract, which would be important for assessing statistical power. The research represents a sophisticated approach to understanding how species adapt to human-modified environments.
What the Results Show
The two bee species showed strikingly different genetic responses to urbanization. Andrena florea experienced a significant loss of genetic diversity, increased genetic differentiation between populations, and signs of recent population decline in urban areas. In contrast, Andrena vaga maintained higher genetic diversity, showed better connectivity between populations, and remained demographically stable across the urban gradient.
Despite these opposite demographic patterns, both species showed evidence of genetic adaptation to urban conditions. The researchers identified specific genes and genomic regions that appeared to be under positive selection—meaning these genes were becoming more common because they helped bees survive in cities. Interestingly, some of these selected genes were similar between the two species, suggesting they may be adapting to similar urban challenges.
The genetic diversity in each species was linked to different landscape features. For A. florea, the amount of fragmented habitat edges predicted genetic diversity levels. For A. vaga, the availability of semi-natural habitats (like meadows and grasslands) was the key factor. This shows that each species’ genetic health depends on different environmental features, not simply on how urban an area is.
The researchers found that urban intensity itself—the degree of development and human activity—was not the primary driver of genetic change. Instead, the specific landscape composition and structure mattered more. This suggests that cities aren’t uniformly stressful; rather, the specific arrangement of green spaces, fragmented areas, and developed land determines how bees are affected. The study also revealed that gene flow (bees moving between populations) and genetic drift (random changes in gene frequencies) interacted with selection to shape the final genetic patterns observed.
Previous research on urban evolution often focused on single species or assumed that all organisms respond similarly to cities. This study advances the field by showing that closely related species with different ecological traits can have divergent genetic responses. The finding that some genes show convergent selection (similar changes in both species) while overall demographic patterns diverge is novel and suggests that urban environments create both universal and species-specific selective pressures.
The study doesn’t specify the exact number of individual bees sampled, making it difficult to assess statistical confidence in the findings. The research focuses on only two bee species, so results may not apply to other bee types or insects. The study is observational rather than experimental, meaning researchers observed natural patterns but couldn’t directly test cause-and-effect relationships. Additionally, the research captures a single point in time, so we don’t know how genetic patterns will continue to change in the future.
The Bottom Line
Conservation efforts for urban bees should be tailored to each species’ specific ecological needs rather than applying generic urban conservation strategies. Protecting semi-natural habitats like meadows and grasslands appears particularly important for maintaining bee populations in cities. Maintaining connectivity between bee populations through green corridors may help preserve genetic diversity. These recommendations have moderate confidence based on observational data; experimental studies would strengthen them.
City planners and conservation organizations should care about these findings when designing urban green spaces and habitat restoration projects. Beekeepers and gardeners in urban areas can benefit from understanding that different bee species have different habitat needs. Researchers studying urban evolution and conservation genetics will find this work particularly relevant. People concerned about pollinator decline in cities should understand that one-size-fits-all solutions won’t work.
Genetic changes in bee populations occur over multiple generations, typically years to decades. Conservation efforts to restore bee populations and genetic diversity would likely show measurable results within 5-10 years, though full recovery might take longer. Short-term monitoring (1-2 years) can track whether habitat improvements are attracting bees, while long-term genetic monitoring (5+ years) would show whether genetic diversity is recovering.
Frequently Asked Questions
Do all bees respond the same way to living in cities?
No. Research on two bee species shows they respond oppositely: one lost genetic diversity in cities while the other stayed stable. Each species’ response depends on its specific traits, like how far it travels and what plants it needs, not just how urban an area is.
What landscape features help bees survive in cities?
Different bee species need different features. One species thrives with semi-natural habitats like meadows, while another depends on fragmented habitat edges. This means urban conservation requires understanding each bee species’ specific habitat needs rather than generic green space.
Are bees genetically adapting to city living?
Yes. Research detected specific genes showing signs of positive selection in both bee species, indicating genetic adaptation to urban conditions. However, this adaptation isn’t happening equally—one species is adapting while declining in numbers, while the other maintains stable populations.
How can cities better support bee populations?
Cities should maintain semi-natural habitats and green corridors that connect bee populations, allowing gene flow between groups. Since different bee species need different features, conservation plans should identify which specialist bees live locally and protect their specific habitat requirements.
Why do closely related bee species respond so differently to cities?
The two species differ in dispersal ability, rarity, and host-plant distribution. These ecological traits determine which landscape features matter most for each species’ survival and genetic health, causing divergent responses to the same urban environment.
Want to Apply This Research?
- Track bee sightings by species in your neighborhood, noting the specific location and nearby habitat features (green space, fragmented areas, developed land). Over time, this reveals which bee species thrive in your area and which habitat types support them best.
- Use the app to identify which native plants support specialist bee species in your region, then plant these species in your garden or community space. This directly creates the semi-natural habitat that research shows supports bee genetic diversity.
- Establish a seasonal monitoring routine (spring through fall) to document bee species presence and abundance in specific locations. Compare patterns year-to-year to see whether habitat improvements correlate with increased bee diversity, providing personal evidence of conservation impact.
This research describes genetic patterns in bee populations and should not be interpreted as direct medical or health advice for humans. The findings apply specifically to two solitary bee species and may not generalize to all bee types or other insects. While the research provides insights for urban conservation planning, local conservation decisions should involve consultation with regional ecologists and wildlife experts. This summary is for educational purposes and does not replace professional ecological or conservation guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.