Shifting perspective on the impact of roads on nearby plants and animals

Environmental scientist Steven Brady sets up equipment to study the effects of roads on amphibians.

In a study published this month in Frontiers in Ecology and the Environment, Steven Brady, an ecologist with King County’s Water and Land Resources Division’s Science and Technical Support Section and co-author Jonathan Richardson, assistant professor at Providence College, show that roads and runoff are causing rapid evolutionary change in populations of plants and wildlife living in road-adjacent habitat.

The study,”Road ecology: shifting gears toward evolutionary perspectives,”finds that for a variety of organisms—including amphibians, birds, and plants—evolutionary adaptations to road effects can arise in just a few generations.

Graphic by Steven Brady; symbols courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science


The finding that populations are evolving rapidly in response to negative road effects such as pollution and road kill changes the dialogue about the consequences of roads. While negative outcomes from roads have long been reported, the observation that roads can spur evolution reshapes our understanding of how roads impact natural systems.

However, the authors state that while rapid evolution to negative road effects can lessen the severity of challenges posed by roads, it does not altogether alleviate them. Indeed, for some populations, evolution appears to lessen the capacity to tolerate road effects in a process known as maladaptation. Given the pervasiveness and increasing presence of roads on the planet, developing an understanding of road-induced evolution is critical for effective conservation planning and mitigation efforts.

Takeaways from the study’s abstract:

  • Roads are ubiquitous features of the landscape, affecting 20% of the US land area; globally, roads are projected to increase 60% in length by 2050.
  • The field of road ecology has described many of the negative effects of roads but has generally failed to consider their evolutionary consequences.
  • As shown in many other fields of conservation, evolutionary perspectives often transform our understanding of the ways organisms respond to environmental change.
  • The handful of evolutionary studies associated with roads reveals both positive and negative effects, indicating that evolution can increase or decrease the resiliency of road-affected populations.
  • Evolutionary perspectives are vital if we are to improve our capacity for understanding and addressing the pervasive effects of roads.

Further reading


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KC Water and Land Resources Division

We protect, restore, and manage King County's water and land using the best available science, innovation, and through collaboration with our partners and the community.