Up in Arms

The Rough Skinned Newt- one of the most poisonous animals on the planet. Courtesy of the USGS

Last week, I mentioned that evolution is an ongoing process. In the case of germs and humans, bacteria may develop a more lethal strain, and humans develop genes more adept at avoiding this type of infection. This type of co-evolution is called the evolutionary arms race, and has been seen in many, many examples in nature.

For my first example, I would like to visit the rough-skinned newt. This amphibian is a smallish lizard like animal that lives around fresh water bodies in the Northwest coast. An interesting side note to them is that they are one of the most poisonous animals on earth.

A somewhat dubious story says that three men whom had gone camping were found dead, huddled around a coffee pot with one newt inside of it. What is known is that the poison produced by the newt’s skin is called a tetrodotoxin. This nasty toxin has no known antidote, and kills by stopping the heart’s muscles from contracting. It is 100 percent fatal.

Only one animal can eat this newt with few side effects; the garter snakes that live in the area. It is thought that both the newt’s extreme toxicity and the garter snake’s immunity are due to the evolutionary arms race.

The concept is quite similar to the cold war arms race of the 20th century. The snakes gain a gene that allows it an immunity to the poison of the newt . The newt’s offspring that have the most toxins are the least likely to be eaten by snakes- and pass those high toxicity genes to their offspring. The garter snake’s most successful offspring are subsequently the ones that are more likely to resist the tetrodotoxin.

The arms race keeps going until the newt is the most poisonous animal on earth, and the snake can consume enough tetrodotoxin to kill 20 full grown people. And then, it keeps going.

The concept of the evolutionary arms race has also been dubbed, “The Red Queen Hypothesis.” It is called this because of a line the Red Queen character has in the famous tale Alice in Wonderland, “You need to keep running just to keep up.”

This theory states that evolution is a constantly moving battle between those who need lunch and those that would be lunch. As long as both species survive, you will keep seeing camouflage getting better, teeth getting sharper, and running speeds going up. But that is a subject for next time.