Nature
Australia's invading cane toads evolved longer legs in 70 years — for a strange reason
Since cane toads were introduced to Australia in the 1930s, the leading edge of their spread has sped up roughly fivefold, and researchers found toads at that front have significantly longer legs than toads from older, settled populations. It isn't classic natural selection: it's 'spatial sorting' — the fastest-dispersing, longest-legged toads simply end up next to each other at the frontier and breed together there, concentrating long legs regardless of any survival advantage.