Convergent evolution is the process by which different lineages have evolved similar traits independently (Liu, et al., 2010). Evidence of this can be seen in the evolution of flight among birds and insects.
Convergent evolution of echolocation
Liu et al., (2010) has found evidence of convergence of the Prestin gene, which is responsible for echolcation in bats and dolphins. This discovery is unprecedented, as evidence for two highly divergent groups sharing a complex phenotype, is rare.
Liu, Y., Cotton, J. A., Shen, B., Han, X., Rossiter, S. J., & Zhang, S. (2010). Convergent sequence evolution between echolocating bats and dolphins.Current Biology, 20(2), R53-R54.