By Carl Zimmer
Monarch butterflies eat only milkweed, a poisonous plant that should kill them. The butterflies thrive on it, even storing milkweed toxins in their bodies as a defense against hungry birds.
For decades, scientists have marveled at this adaptation. On Thursday, a team of researchers announced they had pinpointed the key evolutionary steps that led to it.
Only three genetic mutations were necessary to turn the butterflies from vulnerable to resistant, the researchers reported in the journal Nature. They were able to introduce these mutations into fruit flies, and suddenly they were able to eat milkweed, too.
Biologists hailed it as a tour-de-force that harnessed gene-editing technology to unscramble a series of mutations evolving in some species and then test them in yet another.
Continue reading by clicking the name of the source below.