After World War II, a few snakes reached Guam; they now number up to 30,000 per square mile, and scientists found 19,000 hidden genetic changes

Brown tree snake (Photo: Canva) After World War II, a small number of brown tree snakes somehow made it to Guam, likely hidden in cargo, and the island has been dealing with the consequences ever since. Today, the snakes are so widespread that in some parts of the U.S. territory they reach densities of up to 30,000 per square mile, driving native birds to local extinction and causing hundreds of power outages every year.For decades, that scale of success puzzled biologists. The invasion started from a tiny founding population, so the snakes should have faced severe inbreeding and limited genetic flexibility. Instead, they adapted, spread, and became one of the most notorious invasive species in the world.A new study led by the University at Buffalo helps explain how they managed it. Using advanced long-read genome sequencing, researchers uncovered thousands of hidden DNA changes that had not been visible with older genetic methods. The surprising result: these snakes may be much more genetically versatile than scientists once believed.A famous invasion storyBrown tree snakes are native to Australia and parts of the South Pacific, but Guam offered them the perfect opportunity to thr...