It's in the Genes

scienceblogs.com:

The echolocation abilities of bats and whales, though different in their details, rely on the same changes to the same gene - Prestin. These changes have produced such similar proteins that if you drew a family tree based on their amino acid sequences, bats and toothed whales would end up in the same tight-knit group, to the exclusion of other bats and whales that don't use sonar.

This is one of the most dramatic examples yet of 'convergent evolution', where different groups of living things have independently evolved similar behaviours or body parts in response to similar evolutionary pressures.

It is one of a growing number of studies have shown that convergence on the surface - like having venom, being intelligent or lacking enamel - is borne of deeper genetic resemblance.