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City Fit: NSF Grant Explores Evolution in Urban Areas 9/25/2020

Principal investigators: Dr. James Gibbs on left, and Dr. Brad Cosentino on right

SUNY College of Environmental Science and Forestry (ESF) scientists have received $540,000 as part of a four-year, $1.5 million National Science Foundation grant to explore principles that shape evolutionary processes in urban areas.

"Urban areas are the fastest growing ecosystem on Earth," said James Gibbs, Distinguished Professor and co-principal investigator. "Ecological conditions vary sharply between cities and rural areas and may cause divergent natural selection between urban and rural populations. Understanding what life can and will persist in cities is critical to our well-being. What species will survive? What species will thrive?"

Researchers will study urban evolution by examining melanism in gray squirrels. More melanic (black) squirrels tend to be found in urban areas than rural areas, but the reasons for this pattern are poorly understood.

"Gray squirrels are the most common and visible animals in cities in the United States and abroad. As such, they provide an ideal model system for exploring the different ways urbanization affects evolution," indicated Gibbs.

Gray squirrels have two common coat colors - gray and melanic - that are determined by a single gene with one small change that affects that amount of pigment in the squirrel's fur. The melanic form used to be common in much of the northeastern United States, but today it is abundant primarily in cities. This research seeks to determine why melanic squirrels declined in rural forests but persist in cities.

"We expect that results from this project will shed light on fundamental questions about how urbanization affects the way organisms evolve, that is, the degree to which evolutionary change in cities and surrounding rural areas is due to natural selection, chance, or a combination of both," Gibbs said. "Ultimately, research results will illustrate evolutionary mechanisms in cities, informing urban planning and design that maintains and augments urban biodiversity for the highly diverse human populations that characteristically live in urban areas."

Toward this goal, the study, which is a collaborative effort with researchers at Hobart and William Smith Colleges and Yale University, will test several hypotheses, including whether the color difference between gray and melanic squirrels is caused by natural selection or genetic drift; novel selection pressures introduced by urbanization; or landscape features that select for altered gene flow and generate region-specific coloration patterns.

The project, which will begin in January 2021, will use tens of thousands of data points already collected by school-aged citizen scientists across the country, using squirrelmapper.org, an online app developed by Gibbs and recognized as one of the "Top 19" citizen science projects of 2019 by SciStarter. The app, integrated with iNaturalist.org, enables participants to record squirrels in the field, classifying them by coat color.

"Apps like squirrelmapper.org and projects like this allow teachers across the country to overcome obstacles associated with field trips to natural areas," said Gibbs. "Teachers increasingly use inquiry-based projects to teach ecology in the schoolyard and have expressed a desire to have the data that is collected through squirrelmapper.org to be used to improve evolution education. This grant will help us respond to this request. K-12 students will be at the center of the Squirrelmapper curriculum, and we will provide them with opportunities to connect and contribute to the global scientific community."