John L. Bucksbaum Vice Chair, Facilities and Administrative Services Board of Trustees | Field Museum
John L. Bucksbaum Vice Chair, Facilities and Administrative Services Board of Trustees | Field Museum
The Field Museum in Chicago has conducted a study on how urbanization is influencing local wildlife, specifically focusing on rodents. The research, published in the journal Integrative and Comparative Biology, was co-authored by Stephanie Smith, a mammalogist and XCT laboratory manager at the museum. She emphasized the importance of natural history collections, saying, “Museum collections allow you to time travel.”
The museum's mammal collection contains over 245,000 specimens from around the world, with a significant number from Chicago. These specimens span more than a century, offering researchers insights into evolutionary changes over time. "We’ve got things that are over 100 years old," Smith noted.
Researchers focused on two species commonly found in Chicago: eastern chipmunks and eastern meadow voles. Anderson Feijó, assistant curator of mammals at the museum and co-author of the study, explained their selection: “We chose these two species because they have different biology.”
Field Museum Women in Science interns Alyssa Stringer and Luna Bian measured skulls from 132 chipmunks and 193 voles. They concentrated on skulls because they provide information about animals' sensory systems and diet. “From the skulls, we can tell a little bit about how animals are changing,” Smith stated.
The study used geometric morphometrics to analyze 3D scans of rodent skulls. This analysis revealed small but significant changes over the past century. Chipmunks' skulls increased in size while their teeth rows shortened. Voles showed reduced bony bumps related to hearing.
To understand these changes, researchers examined historical records of temperature and urbanization levels using satellite images dating back to 1940. They discovered that urbanization correlated with skull changes more than climate did.
Feijó remarked on chipmunks' adaptations: “Over the last century, chipmunks in Chicago have been getting bigger.” He attributed this to their consumption of human-related food rather than traditional nuts and seeds.
Smith suggested that voles' smaller auditory bullae might help them manage city noise better: “We think this may relate to the city being loud.”
Both researchers highlighted how human activity impacts wildlife evolution. Feijó stated: “These findings clearly show that interfering with the environment has a detectable effect on wildlife.” Smith added: “Change is probably happening under your nose.”
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