Warm Weather Gives Pack Rats a Leg Up on Rattlesnakes

The secret to surviving a rattlesnake bite may lie not just in genetics, but in the temperature outside: New research reveals that weather and diet can shape how well desert wood rats, a form of pack rat, resist deadly venom. In a new study published Wednesday in Biology Letters, researchers discovered that wood rats acclimated to an environment kept at 85 degrees Fahrenheit produced blood serum that better neutralized rattlesnake venom than wood rats acclimated to a 70-degree environment. Scientists also found that blood serum from wood rats that were fed their natural diet of creosote, a toxic plant, was less effective at combating venom than serum from rats fed standard chow, per a release.

Desert wood rats, or Neotoma lepida, can survive 500 to 1,000 times the venom dosage that would kill a lab mouse, as their blood contains proteins that neutralize rattlesnake venom. The serum samples were originally collected in 2014 in southwest Utah by study co-authors Patrice Kurnath Connors, a professor of biology at the Colorado Mesa University, and Denise Dearing, a professor of biology at the University of Utah. "We figured the rattlesnake resistance would be the same whether they were in the cool or the warm [environments], and that when we fed them creosote in either temperature, the rattlesnake resistance would drop," says Dearing. "We weren't really thinking about the effect of temperature on rattlesnake resistance, so we were pretty surprised by the results."

The study's lead author, Matthew Holding, an evolutionary biologist at the University of Michigan Life Sciences Institute, says, "Even across different populations of the same snake species, eating the same prey, we see evolutionary differences in their venoms." He adds, "With this study, we really wanted to dig into what drives these differences in the natural coevolutionary arms races between the snakes and their prey." Science notes that "the findings demonstrate the complexity of predator-prey interactions and underscore the many factors that can be in play when it comes to the evolution of venoms and resistance." (This content was created with the help of AI. Read our AI policy.)