KEY WEST, Fla. - The Florida Keys, already dealing with invasive exotics from melaleuca to iguanas, have added another to the list of unwanted newcomers: the African Gambian pouch rat. Biologists and conservationists in the Keys say the rodent needs to be eradicated, before it increases its range and harms native species that live in natural areas of the Keys. Although it is unclear how or why the rat — which can grow as big as a raccoon — was released on Grassy Key, biologists are saying the animal could be devastating to the Florida Keys' ecological system. The omnivores,...