Francis Quang-Hai Dinh’s initial summer at McGill University was spent riding his bicycle around Montreal’s parks in search of squirrels. He visited nearly 200 green spaces spanning from Mirabel to Saint-Bruno, meticulously observing and documenting over 800 grey and black squirrels. What began as a university assignment soon evolved into a personal project driven by his fascination with how the city’s geography and meandering water systems influence evolution.
Dinh, who is currently pursuing integrative biology at the University of Illinois Urbana-Champaign, conducted the unique research without a car, relying solely on his bicycle due to limited public transportation options in suburban areas. This made him the sole researcher known to manually survey squirrels park by park across the region.
His findings revealed that approximately 12% of squirrels in Montreal have black coats, with the prevalence of black squirrels increasing as he moved further north. In regions just north of Laval, up to 40% of squirrels exhibited black coloring, compared to around 20% on the island of Laval, 15% on the island of Montreal, and a mere 2-3% on the south shore of Montreal. The study attributed this variation primarily to temperature, as black squirrels, with their better heat-absorbing properties, thrive in cooler climates.
Additionally, the density of forest cover played a significant role in the prevalence of black squirrels. Areas with a denser tree canopy provided a darker backdrop where black squirrels could blend in better, showcasing a form of natural camouflage.
The research, led by Allison Roth, an assistant professor at the University of Missouri and former McGill postdoctoral fellow, focuses on using squirrels as a model to study how urban environments drive evolutionary changes. Roth highlighted that Montreal’s unique urban layout, segmented by waterways like the St. Lawrence River, creates micro-environmental variations that lead to diverse genetic and physical adaptations within the same animal population.
Contrary to previous beliefs that human development was the primary driver of evolutionary changes in city animals, the study emphasized that cities are just one piece of the puzzle. Urbanization alters local temperature and vegetation cover, while natural barriers like riverways also influence wildlife adaptations indirectly through environmental factors.
The research, titled “Fine-scale spatial variation in eastern grey squirrel melanism across a complex urban landscape,” delves into the intricate changes in wildlife on a neighborhood-by-neighborhood basis, providing valuable insights into how urban environments shape evolutionary processes. This study forms part of a special feature by five ecology journals exploring how collaboration and data analysis can address significant ecological questions.
Reflecting on his research, Dinh expressed a newfound perspective on wildlife, noting the coexistence of urban development and nature. He emphasized that despite human modifications to the environment, wildlife will continue to adapt and endure, challenging the notion that cities and nature are separate entities.