Wikipedia:Reference desk/Archives/Science/2022 August 18

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August 18

Climate

Moved from Wikipedia:Teahouse § Klima

Ist die aktuelle Klimaveränderung natürlichen Ursprungs oder / und Folge der Industrialusierung. 2.247.248.83 (talk) 03:00, 18 August 2022 (UTC)

Bitte versuchen Sie es mit dem Referenzschalter.

Original post translated through Google Translate: Climate / Is the current climate change of natural origin or / and the result of industrialization. 🐶 EpicPupper ^{(he/him | talk)} 03:05, 18 August 2022 (UTC)

The answer is "Yes". ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:45, 18 August 2022 (UTC)

The climate has a "natural" change component responsible for ice ages and interglacials, which is discussed in the article Milankovitch cycles. Overlaid on that process there can now be little doubt there is also a human-induced climate change. So the answer is "und nich oder". Were it not for global warming on a 50-year timescale which rightly worries most people, we might be worrying about global cooling on a couple-of-century timescale: i.e. when we might expect the current interglacial to end. Mike Turnbull (talk) 14:20, 18 August 2022 (UTC)

Disproportionate toxicity of small animals

Why did some small animals, such as Irukandji jellyfish, evolved disproportionately potent toxins relative to the size of their prey which can also kill much larger animals, such as humans? One may think that from an evolutionary standpoint, evolving such excessively toxic substances would be costly and their evolution would stop at a point sufficient to kill typically sized prey, yet they exist. Why is that? 212.180.235.46 (talk) 13:05, 18 August 2022 (UTC)

"Researchers conjecture that the venom possesses such potency to enable it to quickly stun its prey, which consists of small and fast fish". In other words, just one or two stingers will quickly stop the fish. I doubt that humans enter into it's evolution! Martin of Sheffield (talk) 13:12, 18 August 2022 (UTC)

One thing to consider; such toxins are also deadly to predators as well... Many of which may be considerably larger. --Jayron32 13:15, 18 August 2022 (UTC)

I did consider that, but the article doesn't mention predation so I didn't mention it. Maybe not deadly for something the size of a baleen whale, but unpleasant enough to diswade feeding perhaps? Martin of Sheffield (talk) 14:05, 18 August 2022 (UTC)

Animals that are toxic to dissuade predators usually advertise so with bright colours (some frogs, salamanders, fish, insects). This jellyfish is almost invisible; there's no way a filter-feeding baleen whale would see it before crushing it in its mouth. Large non-filterfeeding hunters wouldn't target such a small prey, so the toxins only help against predators up to maybe 5 kg. PiusImpavidus (talk) 09:11, 19 August 2022 (UTC)

Often if a prey species uses some chemical deterrent in some way against predators it's accompanied with aposematism: distinctive (often bright) marking coloration or other signaling that they are unpalatable or dangerous. This strategy relies on either predators surviving contact with unpleasant effects (and thus learning to avoid the colors and teaching others to do the same), or being seriously wounded or dying and thus selective pressures encouraging future generations to avoid the species. (The prey need not survive the encounters for this to be effective. Often both strategies are working against a range of predators. And of course with mimicry other species can copy the coloration, get the benefits of the credible warning, but not the bear the cost of producing deterrent chemicals). A species -- especially hunters in the middle of the food chain -- might also find it beneficial to have a mixed strategy of camouflage and chemical deterrent depending on their environment.

So the jellyfish you bring up seems to tick none of those boxes, which would likely indicate it's using the venom mostly to catch its own prey as the article suggests. However, there are plenty of other evolutionary phenomena: consider the famous case of the mongoose versus the cobra (among other small predatory mammals and snakes), in which the mongoose has evolved significant natural resistance to its prey snake's venom. This could well have been (or be an ongoing) evolutionary arms race in which the snake species upped its venom potency and/or dosage while the predator upped its resistance and/or strategy. The result in isolation may be a snake whose venom is significantly overpowered for defeating its own prey and most other predators. It is possible a similar phenomenon (or a completely different one -- biology is enormous) happens with some jellyfish. One problem though with studying jellyfish evolution of any kind is that the fossil record is minuscule. SamuelRiv (talk) 16:48, 19 August 2022 (UTC)

There is something about this question that seems counter-intuitive, given my very incomplete understanding of biology and evolution. The toxin in question seems to be a sodium channel activator. Ion channels are a diverse class of membrane proteins that play critical roles in cellular physiology...it is not surprising many toxins have evolved to block or activate ion channels, often with exquisite potency and selectivity...venoms provide a virtually untapped reservoir of millions of bioactive peptides with highly diverse sequences and structures, including many that target ion channels of clinical importance.[1] Isn't it enough to say that given we have evolved in a way that these ion channels are so critical to our physiology, and that targeting them is a very successful strategy for venomous species? Evolution has created a huge reservoir of toxins and it seems hardly surprising that we have an example of one that is particularly deadly. Trying to go beyond that to a more exacting explanation according to the fitness of the organism seem to somehow deny the huge diversity and chance underlying evolution. Is there some principle used to decide when you try to explain such mechanisms using an argument based on the "fitness" of the organism, and when you just shrug and say that nature had lots of chances and this is just the way things worked out? fiveby(zero) 18:14, 19 August 2022 (UTC)

You're absolutely correct that many descriptions in evolutionary biology can be teleological, that is: "the animal is this way because that is what's best, and that is what's best because this animal is currently optimally adapted to its environment" or something along those lines. However, teleological language can be a useful shorthand in biology and also fields like economics to describe the importance of constant selective (or market) pressures. Venom production in an animal is expensive: the venom has to be produced and stored (short-term only) in specialized structures kept segregated from bloodstream, and the production often requires specific nutrients that the animal must seek outside its ordinary diet. If the intent is to use venom to deter predators, an effective deterrent strategy could potentially be massively favored by selection despite the cost, while an ineffective one can make the animal less successful than one that foregoes venom production entirely. Balancing strategies in deterring predators can be difficult, as one must be able to potentially defeat/deter a wide range of different weights, health conditions, and even families of species with the same basic tool and *possibly* the ability to somewhat control dosage. In the end you want to deter the predators that either kill you the most or otherwise compete with you the most, and the quickest way to deter predators is to keep them alive for the poisoning so that avoidance is learnt and taught in one or two encounters, rather than relying solely on thousands of generations of selection to get the message across. And with large amounts of the evolutionary timeline of jellyfish being completely unknown, I imagine one has to rely more on math and chemistry and the evolution of other species in its food web to hypothesize about the origins and purpose of its venom.

Again, to emphasize, this isn't like an argument by population bottleneck or genetic drift in which random phenotypes may emerge that wouldn't have been selected for otherwise, that nonetheless prove suitable or sustainable. Venom use in jellies is so universal that that's not really the scope here -- at issue is why such a tiny, barely visible jelly has so potent of a venom (and by extension why do many small animals have potent venoms -- but the examples given are all cases in which venom is widespread in the family, so it's again a matter of why spend the money on higher doses of more potent venom if your prey is small and it may be overkill even on your largest predators?). SamuelRiv (talk) 18:51, 19 August 2022 (UTC)

Thanks for the Stanford link, tho it's quite a bit of reading. I'll return the favor with "Chironex fleckeri (Box Jellyfish) Venom Proteins" and "Phylogenetic and Selection Analysis of an Expanded Family of Putatively Pore-Forming Jellyfish Toxins". The first has a phylogenetic tree grouping two toxins with with widely different properties, but if i am reading correctly both types have been seen in Malo kingi. Variation within the species has very different toxicity and mechanism. The second has a quote i liked: "...JFTs have evolved in interesting and previously underappreciated ways across Medusozoa. Furthermore, these toxins may possess many diverse functional roles within the venom repertoires across other medusozoan species, given that the group displays significant developmental (polyp vs. medusa, coloniality vs. solitary, etc.) and ecological diversity (variation is size and habitat, prey type and predation, symbiosis, etc.)

Biologists observing a large number of species might identify an evolutionary phenomenon and describe with such a teleological narrative of development, but it's difficult for a layperson (or at least for me) to see how useful or applicable they intend the description to be. For instance, there is reason to doubt your argument (or observation we should keep in mind) based on "cost". Toxin effects are complicated and species specific. Looking at the Price equation or Lewontin’s principles suggest a few different ways to construct something called "cost", is it well defined or well enough understood and agreed shorthand? 11,000 species somehow paid the "price" of nematocytes and there is now a large variation in both size and toxicity. I don't know if these are valid objections or stretching a useful observation beyond its intent. I'd suggest that maybe M. kingi didn't pay a "price" for something highly toxic to large vertebrates, because of the variation in toxicity within the species. But then i don't think we should be looking at species, but populations within an environment so you tell me!

These descriptive narratives of applications in evolution and natural selection are really all the casual reader sees, up to and including involving human behavior, cognition, or psychology. Even explaining social issues or advocating an outcome: lobster hierarchies giving insights into the workplace. It's "evolution" at work. Teleological language aside, I am just wary of explanations of evolution by default. Also every explanation seems to exclude possible histories and variations and if applied beyond intention to deny some part of your "biology is enormous". fiveby(zero) 00:18, 22 August 2022 (UTC)

"Deadly Innovations: Unraveling the Molecular Evolution of Animal Venoms" might be useful. fiveby(zero) 16:07, 22 August 2022 (UTC)

"Sea anemone toxins affecting voltage-gated sodium channels - molecular and evolutionary features" suggests concerted evolution for rapid toxin production and a "dosage effect" and maybe other relevant discussion. fiveby(zero) 17:33, 22 August 2022 (UTC)

Lina Medina

Is very easy to find photo and images of Lina Medina, but it seems there is not video footage existent. Have you noticed that? It is possible to find? 62.18.1.163 (talk) 14:10, 18 August 2022 (UTC)

Lina Medina is not a public figure, and as such, it is not surprising that there does not exist any video footage. Prior to the widespread adoption of smartphones since the turn of the 21st century, most people lived their entire lives without being filmed. --Jayron32 14:18, 18 August 2022 (UTC)

The article says films were made. Abductive (reasoning) 02:48, 19 August 2022 (UTC)

Not everything that exists is publicly accessible. While the Internet makes it feel like it should be, there is still a LOT of such things that have never been made so. --Jayron32 13:43, 19 August 2022 (UTC)

Also that some of them were lost, and the remainder never published. They are medical records of a 5-y-o child, presumably naked, illustrating aspects of her pregnancy, and the person is still alive – medical confidentiality obviously applies to them. {The poster formerly known as 87.81.230.195} 90.209.121.96 (talk) 04:04, 19 August 2022 (UTC)

Well, if Wikipedia somehow gets its hands on the pictures / films, it is not bound by rules that apply to medical professionals. But we still have Wikipedia:Image_use_policy#Moral_issues that would clearly forbid the use of such stuff. Tigraan^{Click here for my talk page ("private" contact)} 09:11, 19 August 2022 (UTC)

Wikipedia would be bound by American laws. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:28, 19 August 2022 (UTC)