Human activities and rapid urbanization are affecting contemporary evolution in many species. This bears implications for the sustainability of ecosystems on a broader scale. It was affirmed in a study led by the University of Washington.

The study examined 1,600 cases of global phenotypic change to trace the linkages with human induced urbanization. Visible traits of such impacts are discerned from changes in size, behavior and development. It also said urbanization is affecting the gene structure of species in various ecosystems.

The paper published in the Proceedings of the National Academy of Sciences has Marina Alberti as the lead author. She is a professor of urban design and planning and a serving director of the UW College of Built Environments' Urban Ecology Research Lab.

"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," said Alberti.

Co-author John Marzluff also commented on the study's significance. He said the conclusions affirm that heavy adjustments are being made by plants and animals to cope with the challenges of an increasingly urban world.

He said they demonstrate the "power of natural selection where we live, work, worship and play."

The study notes that challenges faced by many species from rapid urbanization are driving them to adapt or relocate with some going extinct.

While scanning many urban ecosystems for signs of human-induced changes across species, the study made 1,600 observations for tracking phenotypic changes. It also sought to distinguish the signals of human-made disturbances and non-urban factors in the ecosystems.

Human-Induced Urban Disturbances

Many of the human-led disturbances in ecosystems include pollution of lakes, effluents flowing from power plants, animals' relocation and global warming affecting birds' reproductive patterns.

Alberti said seed dispersal, vulnerability to contagious diseases and changes in migration levels of many species are effects of such changes.

The study aired the concern that "urban-driven contemporary evolution" is having a serious effect on the sustainability of ecosystems that range from a smaller to a planetary scale.

An example of evolutionary changes in species from urbanization comes from transmission towers with zinc coating that hikes zinc tolerance among many plant species.

Alberti sums up that the research has underscored the need for partnership among evolutionary and conservation biologists to craft strategies of conservation to tackle such changes toward a desirable future.

Other Effects Of Urbanization

Meanwhile, a study revealed that staying in close proximity to a major highway would escalate the chances of being afflicted with dementia.

The risk is high for people living within 164 feet of a road with 7 percent more probability of contracting dementia. The risk decreases to 4 percent for people living 328 feet away and it comes down to 2 percent risk if people are living 656 feet away.

"There is a gradient of increased risk as you get closer to major roadways," noted Ray Copes, head of environmental and occupational health at Public Health Ontario, who is a co-author of the study.