Francis Quang-Hai Dinh spent his first summer at McGill University exploring Montreal’s parks on his bicycle, tracking down squirrels. He visited nearly 200 green spaces, documenting over 800 grey and black squirrels. What began as a simple undergraduate task evolved into a passionate endeavor to understand how the city’s layout and water systems influence evolution quietly.
Dinh, who is now pursuing integrative biology at the University of Illinois Urbana-Champaign, relied on his bike for transportation due to limited public transit options in suburban areas. He became the sole researcher known to conduct manual squirrel surveys park by park across the region.
His research revealed that approximately 12% of squirrels in Montreal are black on average. As he ventured further north, the prevalence of black squirrels increased. In areas north of Laval, he found up to 40% of squirrels were black. The percentage decreased to around 20% on the island of Laval, 15% on the island of Montreal, and dropped to 2-3% on the south shore of Montreal. The study attributed these variations primarily to temperature, with black squirrels benefiting from better heat absorption due to their darker coloration.
Additionally, the density of forest cover played a role in squirrel coloration variations, as black squirrels are better camouflaged in areas with a denser tree canopy.
The study’s senior author, Allison Roth, highlighted that the research uses squirrels as a model to explore how urban environments drive evolutionary changes. Montreal’s diverse neighborhoods, varying tree cover levels, and natural boundaries like the St. Lawrence River create unique environmental conditions that can lead to genetic and physical adaptations within animal populations.
While previous studies typically compared urban and rural environments broadly, this research delves into neighborhood-specific changes in wildlife. It challenges the notion that human development alone drives evolutionary shifts, emphasizing that cities are just one component of a complex ecological puzzle. Urbanization indirectly influences melanism in squirrels through factors like vegetation structure and winter microclimate.
The study, “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” underscores the importance of understanding how evolution occurs in response to urbanization. It is part of a special feature by five ecology journals examining how researchers collaborate to address significant ecological questions.
For Dinh, this experience has transformed his perspective on wildlife, blurring the distinction between city life and nature. Despite human modifications, wildlife continues to adapt and thrive in diverse environments.