One of the world’s rarest amphibians — the ancient, aquatic axolotl — has shown signs of adapting successfully to a new setting after scientists introduced it into man-made wetlands in Mexico. Offering a ray of optimism for the endangered species known as Ambystoma mexicanum, a group of researchers recently placed 18 axolotls bred in captivity into two specially constructed wetland habitats near Mexico City, an initiative aimed at reversing the trend of population decline caused by pollution