Cool Garter Snake Research From Utah State University

[Cazador]

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 (http://www.usu.edu/prm/newshighlights/gartersnake/)

[Stefan-A]

So instead of just building up a tolerance and the newt responding with higher quantities, T. s. concinnus has built up a complete immunity to that type of toxin?

Oh, and I came across this blog a few hours before this thread came along: Deadly newt no match for highly evolved garter snake | Science Blog (http://www.scienceblog.com/cms/node/7478). What a coincidence.

[Sid]

Thanks for sharing Rick. Really interesting:) .

Sid

[Gijs & Sabine]

Very interesting indeed ! So if I understand it correctly only the red spotted have this immunity. Maybe other garters develop the same immunity as well in the future.....
Thanks for sharing Rick!!

Sabine

[abcat1993]

A few questions.
If you breed that mutated snake with other ones, for example an eastern, would that mutation go into the offspring? (we studied all this last year and I already forgot it all)
And, Do all red spotted garters have the mutation? Sorry, I didn't watch the video yet.

[Thamnophis]

Interesting information Rick. Thanks for sharing.

[Elliot]

That is pretty neat.

[Cazador]

That's right, Stefan. Even the newborns would be immune.

Sabine,
I've read papers that say there is a correlation between the amount of red on garter snakes and their ability to eat toxic species. I know that the California red-sided garter has a degree of immunity to toxic newts and salamanders in its diet, but I don't know if it has the same mechanism. I suspect it does, though. I wouldn't be surprised if this mutation is more widespread than we know among other species and subspecies.

Matt,
If the mutation happened in a germ cell (sperm or egg), then the immunity would be heritable. This obviously happened in this case, since the phenomenon is so widespread. Since the mutation exists in germ cells, then you could interbreed with an eastern, giving the eastern's offspring immunity. It may not occur in one generation, though. If the mutation is a dominant trait, then all of the offspring would have immunity. If it's a recessive trait, then none of the first generation of offspring would be immune. If the offspring mated among themselves, then statistically speaking, only 1 in 4 would would be immune. This is probably a dominant trait, though, so all of the offspring would be immune. Any red spots that aren't immune would die if they ate these toxic newts, so I suspect that practically all have the mutation (and immunity).

Rick

[abcat1993]

I guess a punnett square would help (one thing I did remember :D). Yeah, thanks for the biology lesson.

[ssssnakeluvr]

not sure if the red color has anything to do with the immunity...wandering garters eat salamanders and toads on a regular basis, they have no red...I have seen them eat frogs, toads, and salamander with their skin secretions and have no problems.... Many different garters may hae that type of immunity...red siders in Kansas eat a lot of toads...these toads secrete a nasty milky stuff when getting munched...doesn't bother the snakes, but dogs sure can't stand it!

[Cazador]

That's one problem with correlations. They help to identify general patterns, but exceptions are tolerable in their model. Still, there are a lot of examples (with exceptions) of brightly colored species being either toxic or resistant to the toxins of noxious species.

[Stefan-A]

Is that red coloration "intended" as a warning to birds in particular, or are there other predators that can see color?

[Snaky]

A very interesting video.

[Cazador]

Evolution works by chance mutations that result in appearances (phenotypes) or functions (physiology) that give the affected individual a competative advantage and allow them to survive and reproduce more efficiently that those lacking the beneficial mutation. Mutations that aren't beneficial can either be neutral or harmful, but there is no "intent" in it... only chance events that may have beneficial, neutral, or harmful outcomes. If birds use the red coloration as a warning signal, then there is a second (perhaps linked) advantage that comes with the change in the ion transporter's mutation. Beyond that, I don't know if other predators, like dogs, cats, coyotes, raccoons, etc. use the red coloration as a visual cue.

[Stefan-A]

Evolution works by chance mutations that result in appearances (phenotypes) or functions (physiology) that give the affected individual a competative advantage and allow them to survive and reproduce more efficiently that those lacking the beneficial mutation. Mutations that aren't beneficial can either be neutral or harmful, but there is no "intent" in it... only chance events that may have beneficial, neutral, or harmful outcomes.
Yes, I know that already, hence the "" around the word "intended". The word is often used in this kind of context even when the writer knows that there is no actual intention behind a mutation or other occurrence. The difference here was that I, in my opinion, acknowledged that "intention" wasn't the right word to use.


If birds use the red coloration as a warning signal, then there is a second (perhaps linked) advantage that comes with the change in the ion transporter's mutation. Beyond that, I don't know if other predators, like dogs, cats, coyotes, raccoons, etc. use the red coloration as a visual cue.And that's what I was wondering.

[Cazador]

Hi Stefan,
Here in the U.S. there are huge misconceptions about evolution (a topic near and dear to me), so I took the opportunity to pontificate a bit. Hope you don't mind.
Rick

[Stefan-A]

No, I don't mind.

[Brian]

A couple of other fun facts about the studies at Utah State university.
1. They have bred Valley Garters (t.s.fitchi) from Utah to Red spotted garters (t.s.concinnus) from Oregon creating integrades to test how well these snakes could withstand the newt toxins. One might expect that they would have less immunity since the Valley garters throughout most of their range aren't sympatric (don't exist with) the newts. What they found was the opposite. The integrades had more immunity. One person I talked to hypothesized this may be because the valley garters eat a lot of toads (woodhouse and boreal) which both have toxins which the Valley garters are immune to and the red spotted garters have the immunity to the newts.

2. They have also produced a paper about how the garters not only are imune to this toxin but actually store it in their livers and if a bird or other predator were to eat them (and their liver) they would likely die from the toxins. They hypothesized that because of this the red may be a warning for birds. You would think then that snakes with more red would be more successfull but their are many areas in Utah and Idaho where valley garters don't have a lot of red. Perhaps these populations aren't eating the toxic toads and newts which would reinforce selective predation on the less red animals. There is no evidence that toxins are anyway related to the red on the snakes.

[Cazador]

Thanks for the update, Brian :). Very cool research.