Assistant Professor of Biology Bradley Cosentino recently co-authored an article in the journal Conservation Biology. The article, “Effects of Urbanization on the Population Structure of Freshwater Turtles Across the United States,” discusses hypotheses tested by undergraduate students at institutions across 11 states, including those in Cosentino’s “Evolutionary Genetics” class. The project was coordinated through the Ecological Research as Education Network (EREN).
“The goal [of EREN] is to establish a network of researchers and students primarily at undergraduate institutions to engage in collaborative research projects in ecology,” says Cosentino. By working with institutions across the country, he says, it’s possible to draw conclusions that hold true across a wider area.
The students in Cosentino’s class sampled turtles in Odell’s Pond on campus and analyzed the data they collected. They combined their results with data from other participating institutions to test whether sex ratio differed between urban and rural areas. “It was a great project to engage students with fundamental ideas in conservation biology, field research, and the basics of statistical analysis,” says Cosentino.
The project revealed an unexpected phenomenon. “We predicted that populations of painted turtles would be biased towards males in urban areas because females have to make movements onto land to create a nest and lay eggs,” says Cosentino—the suggestion being that this made the females more likely to succumb to common sources of mortality such as vehicular collisions.
Instead, the research showed an increased number of females in urban areas, confirming that urbanization does impact turtle populations, but not in the way expected. “The bottom line is that it seems likely that urbanization is affecting turtle sex ratios, but more work is needed to confirm the mechanism. Biological sex is determined by temperature in freshwater turtles, and it’s possible that nests are exposed to higher temperatures in urban areas leading to the production of more females than males ” Cosentino says.
Since completing research with the EREN project, Cosentino has continued to use the topic as a teaching tool. “Having my class continue to sample Odell’s Pond has turned out to be helpful to confirm that sex ratios estimated from a single season of sampling are precise,” he says.
The project was not Cosentino’s first collaborative effort with EREN. In 2017, he led a project on bird-window collisions that received national attention related to proposed federal laws that could limit bird deaths due to collisions with windows in large buildings. A newly tenured faculty member, Cosentino has published more than a dozen journal articles since joining the Colleges in 2012.