Natural Selection in Sticklebacks

Catherine Peichel at the Fred Hutchinson cancer research center made an interesting discovery while studying the stickleback fish in Lake Washington. Over the last 40 years, the fish changed from a freshwater morphology, to a more marine one. This change is linked to a particular gene. She hypothesizes that pollution in the lake has selected for the marine allele, which causes the fish to have more bony armor and may help protect the fish from chemicals in the water.

Link: PDF and also a nice write up by the discovery channel.