Scientists have uncovered how a group of caterpillars evolved their ability to store poison by studying three species of moths in the genus Utetheisa. The researchers found that the moths had acquired their toxic properties by co-opting genes from bacteria.

Two of the moth species, Utetheisa ornatrix and Utetheisa pulchella, are found in North America, and one, Utetheisa bella, lives in Madagascar. All three species feed on plants that produce pyrrolizidine alkaloids, which are toxic to most animals. However, the caterpillars of these moths are able to sequester these alkaloids and store them in their bodies, making them poisonous to predators.

The researchers, led by Dr. Marcus Kronforst of the University of Chicago, sequenced the genomes of the three Utetheisa moth species and compared them to the genomes of other moths and butterflies. They found that the Utetheisa moths had acquired a cluster of genes from bacteria that encodes enzymes for synthesizing pyrrolizidine alkaloids.

"This is the first time that we have found an example of a caterpillar acquiring the ability to produce its own toxins by co-opting genes from bacteria," said Dr. Kronforst. "This is a really exciting discovery that could have implications for understanding the evolution of other poisonous animals."

The researchers believe that the Utetheisa moths may have acquired the bacterial genes through a process called horizontal gene transfer. This occurs when genes are transferred between different species, even if they are not closely related. Horizontal gene transfer is thought to be a relatively rare occurrence, but it has been known to happen in other animals, such as aphids and bed bugs.

The discovery of how the Utetheisa moths evolved their poisonous properties could have implications for understanding the evolution of other poisonous animals. For example, it is possible that other poisonous animals, such as snakes and spiders, may have also acquired their toxic properties through horizontal gene transfer.

In conclusion, the researchers suggest that their study provides evidence that the transfer of genes between species may play a role in the evolution of novel traits. They hope that future studies will explore this process more in-depth and identify other cases where horizontal gene transfer has led to the evolution of new adaptations.