U Study Finds That Increased Temperatures Reduce Toxin Tolerance of Some Animals


Research conducted by U Ph.D. student Patrice Kurnath finds that at warmer temperatures the toxin tolerance of certain mammals is reduced — adding yet another problem to the growing list of environmental complications due to global warming.

Plants often generate toxins as a natural defense. Desert woodrats, the plant-eating species used by Kurnath and chair of the U’s biology department Denise Dearing in the study, generate certain enzymes to counteract the effects of these toxins that are ingested when consuming the plants.

“We’re answering the big question of how warmer temperatures might be affecting animals that eat plants and how they deal with the toxins produced by those plants,” Kurnath said.

The diet of desert woodrats, which are common in Utah and western North America, consists mainly of creosote bush, which produces so many toxins in its resin that laboratory rats often die eating the same amount as the desert woodrats.

The idea behind the experiments hypothesized that as woodrat toxin tolerance levels decreased with temperature increases, that they would reduce food intake and lose weight. Woodrats were removed from the experiment if they lost more than 10 percent of their body weight.

“[Kurnath] really pushed the envelope with this work and expanded knowledge from a different study,” Dearing said. “Not only did she work with different species and a different toxin, she did processes and experiments we have never done before.”

Desert woodrats were able to eat more food at cooler temperatures in both experiments at the end of the research, while almost all of the woodrats in higher temperature climates were removed due to weight loss.

“The most recent study found that warmer temperatures resulted in reduced tolerance in rats,” Kurnath said.

This research adds another dimension to the problems associated with global warming for these species as they deal with an increasingly more toxic diet.

“Not only are surface temperatures increasing, severe weather storms, this is another obstacle that these woodrats and other species are going to have to face,” Kurnath said.

Kurnath plans to extend the study by “digging deeper” into the liver functions and genetic structure of these mammals consuming a highly toxic diet and by “stepping back” and examining their behavior in lab settings. Dearing is working on studying this same trend in marsupials and expects to see results by next year.

Dearing said, “We hope that it will inspire research in other species of mammals.”

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