Cold weather weakens Woodrath’s snake venom defense

For Desert Woodrats, survival against rattlesnake bites may boil down to something as simple as a weather forecast, according to a study published Tuesday by the Biology Letter.

Scientists have found that these excellent rodents are well-known for their impressive impression of toxins, and when temperatures drop, their natural immunity to snakes loses their natural immunity to snakes – a discovery that reveals new complexity in the evolutionary weapon race between predators and prey.

Studies have shown that wood resistance maintained in a colder environment (70°F) is significantly weaker than maintaining in warmer conditions (85°F), suggesting that changes in seasonal temperatures may greatly affect their survival during snake encounters.

“We didn’t really think about the effect of temperature on rattlesnake resistance, so our results surprised us very much,” said Denise Dearing, Distinguished Biology Professor and Senior Author of the Study at the University of Utah. “In cooler environments, the rattlesnake venom is really low. In warmer environments, it’s really high.”

“Study on venoms and animals that resist them have found some very effective pharmacologically active molecules and have led to the development of anticoagulants and even drugs such as Ozempic,”

Desert Woodrats, also known as packaging rats, have evolved extraordinary resistance to toxins. These modest herbivores can survive rattlesnake venom, 500 to 1,000 times higher than rattlesnake venom that killed lab mice. This resistance comes from the deadly components of specialized proteins circulating in the blood that neutralize venom.

The team analyzed blood samples collected from Woodras in southwestern Utah in 2014. These samples have been drawn after the animals were adapted to a warm or cool captive environment. A few years later, when researchers melted and tested these samples, temperature-based differences based on venom resistance remained obvious.

“We can still see significant differences between rats from cold and warm groups,” explains Matthew Holding, an evolutionary biologist at the University of Michigan and lead author of the study. “This tells us that the actual content of their blood is changing due to the ambient temperature, which causes a very different ability of serum to inhibit snake venom.”

The study also reveals another surprising factor that undermines Woodras’ toxic resistance: their native diet. When the researchers compared Woodras to the mixed sugar shrubs consumed by Woodras, their main natural food source, which is rich in toxins, they found that rats on the diet showed the ability to reduce neutralizing snake venom.

This shows that Woodlas faces trade-offs when allocating his body’s resources. Dealing with one stress (whether it is cold temperatures or processing toxic food) seems to undermine their ability to deal with other threats.

“If animals are committed to staying warm or digesting a toxic diet, they may have less energy to produce these anti-toxic proteins,” Dearing notes. “And, turning on the internal heater to keep warm seems to impose a greater physiological cost in terms of anti-toxicity.”

These findings provide insight into why rattlesnake venom composition varies across habitats. Previous studies have shown that even if you prey on the same species, rattlesnakes produce different types of venom according to where they live.

“Even though we ate the same prey in different populations of the same snake species, we saw evolutionary differences in venom,” Holder said. “Through this study, we really want to dig out the reasons for these differences in the naturally co-evolved weapon race between snakes and prey.”

Researchers are now working to determine which specific protein in Woodrat’s blood responds to temperature. Revealing these mechanisms can improve our understanding of venom resistance and may lead to new medical applications.

“Studying the venom and animals that resist them has found some very effective pharmacologically active molecules and has led to the development of anticoagulants and even drugs like Ozempic,” Holdch said.

In addition to potential drug applications, studies have shown that changing climate patterns may undermine the delicate balance of predator predation relations that have evolved over thousands of years. If the warming trend continues, the rattlesnakes may face a more resistant woody that may trigger an evolutionary change in snake venom composition.

The research team included Alexandra Cocoa and Marjorie Madok of the University of Nevada, University of Reno, and Patrice Kurnath Connors, who is currently associate professor at the University of Colorado Mesa, Colorado, who collected the original samples as part of their PhD work.

Funded by the National Science Foundation, the study describes how environmental factors shape the ongoing evolutionary war between predators and prey—at least in the battles of Woodrats, staying warm may be as important as avoiding fangs.

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