Francis Quang-Hai Dinh spent his first summer at McGill University exploring Montreal-area parks on his bicycle, in search of squirrels. He visited nearly 200 green spaces, from Mirabel to Saint-Bruno, where he meticulously observed and documented over 800 grey and black squirrels. What began as a simple undergraduate assignment evolved into a personal project driven by his fascination with how the city’s layout and waterways influence evolution.
Dinh, who now studies integrative biology at the University of Illinois Urbana-Champaign, relied on his bike to navigate suburban areas due to limited public transportation options. He became the sole researcher known to conduct manual squirrel surveys park-by-park throughout the region.
His findings revealed that approximately 12% of Montreal’s squirrels are black on average. The percentage of black squirrels increased as he ventured further north, reaching up to 40% in areas just beyond Laval. The study identified temperature as a significant factor, with cooler climates in northern regions favoring the prevalence of black squirrels due to their superior heat-absorbing black coloration.
Additionally, forest cover played a crucial role, as denser tree canopies provided a darker background that enhanced the camouflage of black squirrels. The research, led by Allison Roth, an assistant professor at the University of Missouri, aimed to use squirrels as a model to study how urban environments drive evolutionary changes.
Roth emphasized that cities like Montreal, characterized by diverse neighborhoods and distinct boundaries such as waterways, create fine-scale environmental variations that can lead to genetic and physical adaptations within animal populations. The study highlighted the intricate relationship between urban development, local temperature fluctuations, vegetation structure, and wildlife adaptations.
While most previous research compared urban and rural environments broadly, this study delved into neighborhood-specific variations in wildlife. It challenged the notion that human development alone dictates evolutionary shifts in animal populations, showcasing how urban sprawl, temperature changes, and natural barriers like riverways collectively shape wildlife adaptations.
The research, published as part of a special feature by ecology journals, underscores the importance of understanding how urbanization impacts wildlife evolution. Dinh reflected on his experience, noting that wildlife persists despite human modifications to their habitats, blurring the line between city and nature.
