A new multi-institution study led by the ÌìÃÀÓ°ÊÓ´«Ã½ that examines 1,600 global instances of phenotypic change — alterations to species’ observable traits such as size, development or behavior — shows more clearly than ever that urbanization is affecting the genetic makeup of species that are crucial to ecosystem health and success.

Their was published Jan. 2 in the . Lead author is , professor of urban design and planning and director of the in the UW .

“We found a clear urban signal of phenotypic change — and greater phenotypic change in urbanizing systems compared to natural and non-urban anthropogenic, or human-created systems,” Alberti said.

She said the findings open new opportunities for advancing our understanding of the role of humans in Earth’s evolution: “By explicitly linking urban development to heritable traits that affect ecosystem function, we can begin to map the implications of human-induced trait changes for ecological and human well-being.”

Rapid urbanization, the researchers write, poses new challenges for species, some of which will adapt or relocate while others go extinct. With this study, they sought to learn whether signs of human-caused change could be detected across species in urban ecosystems worldwide, and to what extent humans and our cities and societies might be speeding up these changes.

They analyzed 1,600 observations of phenotypic change across multiple regions and ecosystems worldwide, in a geo-referenced database, looking to discriminate between such human-caused signals and natural baselines and “non-urban drivers.”

They also assessed the relative impact of several human-caused “urban disturbances,” including the acidification and pollution of lake habitats, the relocation of animals, heat and effluent associated with a power plant, long-term harvesting of certain medicinal plants — even the apparent effects of global warming on the reproductive patterns of birds.

They propose that “urban-driven contemporary evolution” will affect sustainability from the level of the urban ecosystem to the planetary scale.

“The significance of these changes is that they affect the functioning of ecosystems,” Alberti said. “They may inhibit the ability of seeds to disperse, cause exposure to infectious diseases, or even change the migratory patterns of some species.”

Some examples of this include:

• human-caused global warming is prompting the seasonal onset of reproduction to occur earlier in 65 species of migratory birds in Western Europe
• the use of galvanized (zinc-coated) transmission towers creates “novel habitats” characterized by high zinc tolerance in multiple plant species
• the size of brown trout is being affected by fish ladders, which subsequently affects predators and prey

Alberti’s UW co-authors are , professor of environmental and forest sciences, and Victoria Hunt of the Department of Urban Design and Planning. 

Marzluff said, “Our findings of rapid and substantial adjustment by many plants and animals to the challenges of living in an increasingly urban world demonstrate the power of natural selection where we live, work, worship and play.”

But he added that the research also offers hope to those interested in conserving biological diversity: “Certainly many species have been, and will continue to be, extinguished by human action, but we reveal how others are evolving the necessary strategies and physical characteristics to coexist with humanity.”

The research, Alberti concluded, calls for a new collaboration among evolutionary biologists, conservation biologists and urban scientists to better understand how humans may affect evolutionary processes and to inform conservation strategies to steer such changes toward a desirable future.

Other co-authors are Cristian Correa of the Universidad Austral de Chile; Andrew Hendry of McGill University; Eric Palkovacs and Travis Apgar of the University of California, Santa Cruz; Kiyoko Gotanda of the University of Cambridge; and Yuyu Zhou of Iowa State University.

The research was funded by the MacArthur Foundation as well as the National Commission for Scientific and Technological Research and National Fund for Scientific and Technological Development, in Chile.

Members of this research team on the theme of human influences on evolution. The summary to that series recalls Charles Darwin’s century-old comment on evolution that “we see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages.”

The authors of the series added: “Now, however, we have a completely different view. Rapid evolution is occurring all around us all the time. Many of the most extreme examples of rapid evolution are associated with human influences, leading to the oft-repeated assertion that humans are ‘the world’s greatest evolutionary force.'”

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For more information, contact Alberti at 206-616-8667 or malberti@uw.edu, or Marzluff at 206-616-6883 or corvid@uw.edu.

Grant numbers: 14-106477-000-USP (MacArthur Foundation), CONICYT-PAI 82130009 (National Commission for Scientific and Technological Research) and FONDECYT 11150990 (National Fund for Scientific and Technological Development)

That humans and the cities we build affect the ecosystem and even drive some evolutionary change in species’ traits is already known. The signs are small but striking: in cities are getting bigger and in rivers are getting smaller; in urban areas are growing tamer and bolder, outcompeting their country cousins.

What’s new is that these evolutionary changes are happening much more quickly than previously thought, and have potential impacts on ecosystem function on a contemporary scale. Not in the distant future, that is — but now.

A new by of the ÌìÃÀÓ°ÊÓ´«Ã½ College of Built Environments’ published this month in the journal Trends in Ecology & Evolution suggests that if human-driven evolutionary change affects the functioning of ecosystems — as evidence is showing — it “may have significant implications for ecological and human well-being.”

Alberti, a professor of urban design and planning, said that until recently it was assumed that evolutionary change would take too long to affect ecological processes quite so immediately. Such thinking has prevented evidence from coming together “in a way that can only emerge through a cross-disciplinary lens,” she said, observing the interactions between humans and natural processes.

“We now have evidence that there is rapid evolution. These changes may affect the state of the environment now. This is what’s called eco-evolutionary feedback.

“Cities are not simply affecting biodiversity by reducing the number and variety of species that live in urban habitats,” Alberti said. Humans in cities are causing organisms to undergo accelerated evolutionary changes “that have effects on ecosystem functions such as biodiversity, nutrient cycling, seed dispersal, detoxification, food production and ultimately on human health and well-being.”

In the paper, Alberti systematically reviews evidence of “human signatures,” or documented examples of human-caused trait changes in fish, birds, mammals and plants, and their effects on ecosystem function.

In addition to the shrinking salmon, she cites earthworms with increased tolerance to metals, seeds of some plants dispersing less effectively and a type of urban mouse that is a “critical host” for the ticks that carry Lyme disease, leading to spikes in human exposure to the illness.

Songbirds are becoming tamer and bolder and also are changing their tunes to ensure their acoustic signals are not lost in the noisy urban background. European blackbirds are becoming sedentary and have changed their migratory behavior in response to urbanization.

Humans in cities cause these changes through a variety of ways, Alberti said. Our urbanization alters and breaks up natural vegetation patterns, introduces toxic pollutants and novel disturbances such as noise and light and increases the temperature. Human presence also changes the availability of resources such as food and water, altering the life cycle of many species.

Alberti said the emerging evidence prompts serious questions with implications for the focus and design of future studies:

• Can global rapid urbanization indeed affect the course of Earth’s evolution?
• Is urbanization moving the planet closer to an environmental tipping point on the scale of the that introduced oxygen into the atmosphere more than 2 billion years ago?
• Might different patterns of urbanization alter the effect of human action on eco-evolution?

Still, Alberti said hers is not a “catastrophic” perspective, but one that highlights both the challenges and the unique opportunity that humans have in shaping the evolution of planet Earth.

Ecosystems in urban environments are a sort of hybrid, she said: “It is their hybrid nature that makes them unstable, but also capable of innovating.” She explores the theme further in a book to be published in spring 2016, titled “Cities as Hybrid Ecosystems.”

“We can drive urbanizing ecosystems to collapse — or we can consciously steer them toward a resilient and sustainable future,” Alberti said. “The question is whether we become aware of the role we are playing.”

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For more information, contact Alberti at 206-295-7985 or malberti@uw.edu. Twitter: @ma003.