HOW does one species of animal split into two species without evolving in isolation for thousands of years? The problem has vexed biologists since Darwin, but now the curly shells of snails have suggested an answer.
Speciation is easy if two populations become separated and evolve in isolation for millions of years. But sometimes the split happens without a physical barrier. For instance, some crater lakes in East Africa are full of thousands of species of cichlid fish that evolved from a single ancestral species.
Now Mats Björklund and Jonathan Stone at Uppsala University in Sweden have found a quick…
