[atentaten]

Interestingly written article. Raises some questions:

>Newts with weaker poison? They get eaten. Snakes with less resistance? Have trouble finding newts they can choke down, and don’t get to steal their poison. So the arms race continues.

How does a snake know that the Newt has weaker/strong poison? Is it leaving some Newts along and eating others, or is it eating any Newt it runs across? Does a strong-poison newt survive snake consumption attempts?

[riffraff]

it was mentioned elsewhere on the article that the snake may spit out the newt of it's too strong, kinda like a human with chili peppers, I suppose.

[stevenwoo]

Maybe a better way to frame it is over time, there's some genetic sequence that gave the snake a preference for eating this newt in particular out of all potential prey and some other genetic sequence that gives them a bit of resistance so they can store the poison inside them. Those snakes that eat more of them with that genetic makeup, up to a point, are better able to reproduce. Run a few thousand years of iterations over this process, where the snake and newt are in a red queen situation, both running faster and faster just to keep up. It is possible to look at this as situation where neither the snake or newt is conscious of the choices or there is no ability to make decision, there is only following the built in behavior.

[calebkaiser]

I think the preceding sentence in that paragraph answers it. Important context here is that garter snakes tend to swallow prey whole. tldr: a strongly poisoned newt survives consumption attempts.

> And it explains why the newts keep evolving to be more toxic: the snake may want to eat newts generally, but if an individual newt packs enough of a wallop, the snake may just retch it up and go after a different one. Newts with weaker poison? They get eaten. Snakes with less resistance? Have trouble finding newts they can choke down, and don’t get to steal their poison. So the arms race continues.

[thaumasiotes]

> Snakes with less resistance? Have trouble finding newts they can choke down, and don’t get to steal their poison.

That's got to be an extremely weak effect. No snake gets an individual benefit from eating the newts. They get a collective benefit, that predators recognize the species as poisonous, in which all snakes, poisonous and delicious alike, share equally.

The problem is large enough that actually-poisonous animals routinely have delicious mimics of entirely different species who free-ride off of the work the originals do to be poisonous.

You can't explain why snakes apparently need to avoid sending a dishonest signal with a theory that predicts that mimics don't exist.

[calebkaiser]

Yeah that particular aspect of his claim feels like the weakest.

Here is a slightly more in-depth piece where a wildlife biologist mentions other possible forcing functions that cause the snakes to eat the newts: https://baynature.org/2022/04/06/the-bay-area-is-the-center-...

From the article:

> “When garter snakes are born in the late summer, they often live under mats of drying pond vegetation … That happens to be where the newly metamorphosed newts come out in the fall, and we suspect there could be a lot of interaction between predator and prey just because of this overlap in microenvironment. That could have led to strong selection in the past that resulted in such high levels of resistance.”

[the_af]

Interesting.

Let me see if I follow: once the snake population has the warning coloration, and predators know not to eat them, then individual snakes being successful at eating poisonous newts is unrelated to the snakes living long enough to pass their genes (i. e. being successful in terms of natural selection). So a snake which has the right colors will be successful, regardless of its diet.

I wonder, is there a point where mimicry can fail? Can predators at some point start to eat the mimics?

[thaumasiotes]

> Let me see if I follow: once the snake population has the warning coloration, and predators know not to eat them, then individual snakes being successful at eating poisonous newts is unrelated to the snakes living long enough to pass their genes (i. e. being successful in terms of natural selection). So a snake which has the right colors will be successful, regardless of its diet.

Sort of. Whether the snake is poisonous is unrelated to its success, because it dies upon being eaten whether there are consequences to its predator or not. (The article takes some pains to show that this is untrue of the newts, but not the snakes.)

However,

> the snakes living long enough to pass their genes (i. e. being successful in terms of natural selection)

This does not reflect a good understanding. Success means having more children, not having any children.

[the_af]

> This does not reflect a good understanding. Success means having more children, not having any children.

I never said "any children", so your remark doesn't reflect a good understanding of what I wrote.

Try not being pedantic for pedantry's sake, and engage with a question asked in good faith without playing games of one-upmanship.

[thaumasiotes]

You said that living long enough to reproduce constituted Darwinian success. That idea is (1) extremely common, and (2) dead wrong.

[dragonwriter]

> I wonder, is there a point where mimicry can fail? Can predators at some point start to eat the mimics?

The same sources of variation which provide the variety for evolution to work on to evolve avoid eating things with this appearance behavior will also provide variation that evolution can work on to evolve back to do eat things with this appearance behavior; the frequency with which eating causes death vs. the degree to which not-eating results in insufficient nutrition will decide which wins.

[thaumasiotes]

That's all true, but I should point out that there are finer grains of behavior, and some of them asymmetrically make it easier to learn that "actually it's OK to eat those". Predators could evolve the ability to tell the difference between mimics and originals (which is generally rare but extant; consider how human children are taught to tell the difference between coral snakes and king snakes, or how certain birds can reject eggs that they didn't personally lay, but most can't), or they could evolve the behavior of "don't eat things that look poisonous, unless you're really hungry" (which is not rare, and which doesn't work well in a low-mimic environment, but does work very well in a high-mimic environment).

As you note, the behavior you end up with is determined by how much stress the mimics place on you.

[catlifeonmars]

I suspect that as the number of mimics increases (either an individual species or convergent evolution of mimicry, like we see with the number of insects with bee or wasp-like coloration), the relative risk of consuming things that look poisonous drops to a level where it’s sustainable for a population of predators.

To your point I wonder if eventually some truly toxic species can become a victim of their own success

[darkerside]

> The problem is large enough that actually-poisonous animals routinely have delicious mimics of entirely different species who free-ride off of the work the originals do to be poisonous.

When cargo culting goes right.

[thaumasiotes]

Yes, if supply planes couldn't tell the difference between military runways and cult runways, cargo cultists could lure them in and... depending on their defenses... overpower the pilot and take all the stuff.

[kulahan]

I found this on Wikipedia, but tldr they taste test it.

> Successful predation of the rough-skinned newt by the common garter snake is made possible by the ability of individuals in a common garter snake population to gauge whether the newt's level of toxin is too high to feed on. T. sirtalis assays toxin levels of the rough-skinned newt and decides whether or not the levels are manageable by partially swallowing the newt, and either swallowing or releasing the newt.