Surviving the Deadliest Diet: The Power of Extra Gene Copies

As per studies affiliated with the U.S. National Science Foundation, the preference for gene duplications throughout evolutionary periods—rather than the specialization of particular enzymes—enables wood rats to consume the creosote bush, a highly poisonous shrub in desert areas. These discoveries could enhance our comprehension of genetic adaptations to harmful foods in various mammals and potentially explain why some humans process medications differently.

At the close of the ice age, two species of wood rats in particular regions had to alter their diet from juniper to creosote bush following the extinction of juniper in their native areas and the encroachment of creosote. The investigative team, led by Denise Dearing, a notable professor at the School of Biological Sciences at the University of Utah, aimed to uncover how these wood rats adapted to consume the toxic shrub while many other local animals could not. They discovered that natural selection promoted genetic modifications that resulted in the duplication of genes increasing levels of pre-existing detoxification enzymes to eliminate creosote toxins, rather than adapting those enzymes for faster breakdown of the toxic creosote.

“Instead of developing new mechanisms specifically designed to metabolize this toxin, evolution utilized pre-existing systems—merely by increasing their quantity,” remarked Dearing. “However, this doesn’t imply it wasn’t a significant transformation. There wasn’t just an augmentation in the quantity of a singular gene; numerous genes were duplicated across several categories recognized for their involvement in detoxification.”

Humans also demonstrate variability in the number of detoxification-related genes, potentially influenced by certain populations consuming toxic plants. “It’s conceivable that the differences we observe in human detoxification gene counts were stimulated by a similar need to consume toxic vegetation,” Dearing remarked. “These genes additionally facilitate the breakdown of drugs and medications, thus this variability might lead to disparities in how swiftly individuals metabolize drugs.”

The adaptations seen in wood rats also comprised the enhancement of the expression of at least one protein correlated with one of the genes. Moreover, the researchers noted that the transformation, which happened independently in two distinct wood rat species, occurred over a brief period considering the evolutionary timeline of the species. This research was published in the journal Science.