Recent Cornell research found that rattlesnakes, usually feared for their poisonous bites, can indicate negative influences of human activities on the environment. 

The research shows that roads, both large and small, can fragment rattlesnake populations, leading to a decrease in genetic diversity. The research was conducted by Prof. Kelly Zamudio, ecology and evolutionary biology, Rulon Clark, Ph.D. ’04, William Brown of Skidmore College and Randy Stechert, an environmental consultant for the New York State Department of Environmental Conservation, who tracked timber rattlesnakes in upstate New York.

In their paper, entitled “Roads, Interrupted Dispersal and Genetic Diversity in Timber Rattlesnakes,” the researchers state that “even anthropogenic habitat modifications that [do] not destroy a large amount of habitat can create significant barriers to gene flow.”

According to the University, the research team looked at rattlesnakes in 19 different shared wintering quarters — known as hibernacula — in four regions of upstate New York: the Adirondacks, Sterling Forest, Black Mountain and Chemung County. 

The researchers used microsatellite markers to follow these rattlesnakes in each area. The markers helped researchers track the snakes after they left their winter dens, understand the snake’s subsequent reproductive patterns and observe the ways in which the roads in the area altered gene flow. 

They observed the snakes’ behavioral ecology and analyzed their DNA using fine-scale molecular genetics. Tissue samples were retrieved from more than 500 individual snakes, revealing that rattlesnakes with the most closely-related genes came from the same side of the roads where they resided.

While the rattlesnakes differed in genetic makeup on a molecular scale, no physical differences have been observed yet. Zamudio said, “The markers [we chose] were neutral genetic markers. The genes were not specific to any phenotypes.”

Rattlesnakes were chosen as the object of the study for ecological reasons and for convenience. 

“The timber rattlesnake is already on the ‘threatened species’ list, and it is an easy animal to study,” Zamudio said. “Its population is widespread and already under observation in many areas.” 

Zamudio said she hopes that this research will encourage people to preserve wildlife habitats. The fragmentation caused by the roads can make populations genetically less diverse, making them more susceptible to illness or environmental changes that threaten their survival, she said. 

Zamudio cited one positive change that has already occurred due to the study. 

“There is an area in California where a specific breed of newt breeds on a certain road,” Zamudio said. “Opening this road would have caused habitat fragmentation and possibly killed the newts, and so the people of California decided to keep it closed. The newt population was saved.”

The study was funded by the National Science Foundation and the New York State Biodiversity Research Institute.