I came across this little video this evening where researchers from Utah State University found genetic mutations in the ion channels channels of Oregon red-spotted garter snakes. This mutation gives these snakes immunity to tetrodotoxin (the toxin in many salamanders, puffer fish, and so on that makes them deadly). Tetrodotoxin normally blocks sodium channels in nerves and muscles, and stops nervous signals and muscular contractions. Soon thereafter, the victim dies of respiratory paralysis. The mutated sodium channels have a different structure that isn't affected by the toxin, so these snakes can now take advantage of prey that was previously deadly to them. The snakes with this mutation can now take advantage of a new prey source, which gives them a competitive advantage over snakes that lack this mutation. As a result, these snakes have better survival rates to reproductive age (due to the increased food availability), and ultimately produce more offspring like themselves (with the inherited mutation). It's a recent example of evolution at its finest, using the garter snake as a model. Enjoy the video,
Rick

Garter Snake Research