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Author Topic:   Evolution of poisonous vs. non-poisonous snakes
Burnerjack
Junior Member (Idle past 4988 days)
Posts: 1
Joined: 07-31-2010


Message 1 of 13 (571472)
07-31-2010 8:54 PM


Open question : " I can understand Natural Selection as well as mutation through cosmic ray DNA damage/modification. My problem is both of the above mechanisms seem predominately subtractive ( but certainly not always).
Evolution in general is a gradual process of modification right?
Can someone explain why some snakes are not poisonous while others have a most elaborate tool box with behavioral procedures for target identification et. al. Although not a philosophical question, I just have trouble surmising a simultaneous evolution of all the subsystems as well as why would some snakes have this capability and lose it. It would always be useful for enhanced species proppagation, would it not?
Edited by Adminnemooseus, : Add a couple of blank lines.
Edited by Adminnemooseus, : Changed topic title from "mechanisms of evolution" to "Evolution of poisonous vs. non-poisonous snakes"

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Adminnemooseus
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Posts: 3974
Joined: 09-26-2002


Message 2 of 13 (571540)
08-01-2010 2:59 AM


Thread Copied to Forum
Thread copied to the Evolution of poisonous vs. non-poisonous snakes thread in the The Bible: Accuracy and Inerrancy forum, this copy of the thread has been closed.
I have taken the liberty of changing the topic title to make the topic specific to snake evolution.
Edited by Adminnemooseus, : Add post promotion note.

  
Adminnemooseus
Administrator
Posts: 3974
Joined: 09-26-2002


Message 3 of 13 (571542)
08-01-2010 3:04 AM


Thread Copied from Proposed New Topics Forum
Thread copied here from the Evolution of poisonous vs. non-poisonous snakes thread in the Proposed New Topics forum.

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 4 of 13 (571562)
08-01-2010 8:03 AM
Reply to: Message 1 by Burnerjack
07-31-2010 8:54 PM


Hi Burnerjack, and welcome to the fray.
Open question : " I can understand Natural Selection as well as mutation through cosmic ray DNA damage/modification. My problem is both of the above mechanisms seem predominately subtractive ( but certainly not always).
What you are talking about are (generally) point mutations in somatic (body) cells. These mutations are not passed from parent to offspring, and thus do not affect evolution of species, just the bodies of individuals.
In biology, evolution is the change in frequency and character of hereditary traits in breeding populations from generation to generation.
Thus we would be talking about mutations in (male/female) germ cells - the cells that are used in reproduction to make new individuals.
Mutations in these cells can arise from "cosmic ray DNA damage/modification" however a more common source is due to the fact that the DNA replication process is imperfect, so the new DNA strands for the new offspring are not perfect copies of the parent DNA.
My problem is both of the above mechanisms seem predominately subtractive ( but certainly not always).
Subtractive from what?
In evolution we see change in the DNA, that change can either be point replacements, deletions of sections, additions of extra copies of sections, and flip-flop reversals of sections of DNA. These can change the proteins that are produced during the gestation process of offspring, sometimes with lethal results (accounting for the high number of failed conceptions), sometimes with beneficial results, often with little noticeable results (most mutations in offspring that survive to gestation are neutral).
The process of selection then determines whether new mutations add (are beneficial to the individuals survival and reproduction), subtract (are deleterious to the individuals survival and reproduction), or cause no apparent change (are neutral to the individuals survival and reproduction).
Certainly an individual that becomes better at survival or reproduction due to a mutation, and thus produces more offspring during their lifetime than other individuals of a species has had an additive benefit, yes?
Evolution in general is a gradual process of modification right?
Generally yes, however there are some mutations that can cause more rapid observable change than others, particularly if they occur in the parts of DNA that control the sequence of growth and the proteins that are produced during the gestation process of offspring.
Can someone explain why some snakes are not poisonous while others have a most elaborate tool box with behavioral procedures for target identification et. al. Although not a philosophical question, I just have trouble surmising a simultaneous evolution of all the subsystems as well as why would some snakes have this capability and lose it. It would always be useful for enhanced species proppagation, would it not?
Poisonous systems have evolved in a number of species. Usually a poisonous species evolves from a non-poisonous one, however it is possible for such a trait to be lost if there is no survival benefit to it (say on an island with no predators that are affected by the poisons, and plentiful food that can be caught without needing to be immobilized).
Generally speaking, these systems evolve from existing systems with a change in the proteins produced such that a venomous substance is produced instead of a previous non-venomous substance.
And yes, evolving such a system would likely result in increased survival, and as long as it does not affect reproduction, would be generally beneficial.
Does that answer your questions?
Enjoy.
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This message is a reply to:
 Message 1 by Burnerjack, posted 07-31-2010 8:54 PM Burnerjack has not replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


(1)
Message 5 of 13 (571567)
08-01-2010 8:42 AM
Reply to: Message 1 by Burnerjack
07-31-2010 8:54 PM


Venom
Can someone explain why some snakes are not poisonous while others have a most elaborate tool box with behavioral procedures for target identification et. al. Although not a philosophical question, I just have trouble surmising a simultaneous evolution of all the subsystems as well as why would some snakes have this capability and lose it.
As far as I can find out, once venom had evolved at the base of the advanced snakes (Colubroidea), they've all retained venomous saliva, so that there really are no non-venomous Colubroidea, just Colubroidea that wouldn't cause severe symptoms in humans if one bit us in the leg. See here for some discussion.
You are right to think that all the subsystems wouldn't evolve simultaneously. But they didn't need to. The first step was the evolution of venomous saliva. Then you get grooved teeth, which give the snakes an improved delivery system; then true hypodermic fangs. From the link above:
Some non-venomous snakes have been previously thought to have only mild 'toxic saliva' but these results shown that they actually possess true venoms. This makes perfect evolutionary sense, there cannot be a strong selection pressure for the development of advanced pieces of architecture like fangs unless there was already a potent venom worth delivering. Therefore, venom preceeded the fang.
This page has interesting information on the various form of delivery system. As you can see, the simplest system involves: no specially adapted teeth; no muscle specially adapted to pump the venom into the prey; no mobility of the fangs; and the toxins being produced in the salivary glands rather than a specialized venom gland. So clearly it isn't necessary for all subsystems to be present in order for snake toxins to be useful; consequently they didn't all need to evolve at once.

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Tupinambis
Junior Member (Idle past 4655 days)
Posts: 18
Joined: 12-12-2010


Message 6 of 13 (596022)
12-12-2010 12:53 PM


Venomous common denominator
Sorry for the ultra-necropost.
There is some belief that ALL snakes share a common ancestor with Monitor Lizards, Beaded Lizards, and the Bornean Earless Monitor... or at least they're all reasonably close to each other. Both species of beaded lizard are venomous and some of the monitors are (like the Lace monitor and Komodo). With that in mind the first snakes to ever appear were probably venomous or at least had the ability to create venom locked in their DNA somewhere.
Why some snakes are lethally venomous and others aren't I speculate has to do with their life styles. I honestly have no idea what good venom does for a lace monitor, but "non-venomous" snakes don't need venom because they can tackle their prey easily enough without it. A kingsnake can take out a rattlesnake with no venom, an anaconda can take down a caiman with no venom, etc. As for its defensive purposes All nonvenomous snakes probably benefit from batesian mimicry. People sure as hell can't tell the difference between a venomous and non-venomous snake. It is probably easier for most animals to beware of snakes in general opposed to specific individual species.
The venom in beaded lizards serves as a pain augmenter and pretty much nothing else. They certainly don't need it when hunting small rodents and bird eggs.

  
wolfwing
Junior Member (Idle past 4818 days)
Posts: 9
Joined: 12-27-2010


Message 7 of 13 (598031)
12-27-2010 7:09 AM


I had looked this up recently last year due to a creationist asking this question, and from what I learnt, have to look up more specific details in morning but the venom's found in snakes, is actually simular to something else already in snakes in another part of the body some other proteins that has a few mutations and differences in it.
Link here The Evolution Project: 276: Snake venom evolution
I know it's a simular case with the platypus venom, it's simular and likly co-opt'd from proteins found within the platypus imune system link here.
Page not found
Doesnt' say how they safly or such evolved but does show they are modifications of whats already in the body.
PS just joined :> And read this and remembered my previous reserach so had to join and add my two cents.

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 8 of 13 (598033)
12-27-2010 8:39 AM
Reply to: Message 7 by wolfwing
12-27-2010 7:09 AM


Welcome to the fray wolfwing, nice post.
2 sense like this always welcome.
Enjoy

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Blue Jay
Member (Idle past 2698 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 9 of 13 (598042)
12-27-2010 11:52 AM


Pet peeve
A pet peeve of mine is the use of the term "poisonous" when the word "venomous" is intended.
Venom is an offensive weapon that is actively injected directly into the body, and attacks either the nerves or the blood (or both). The term "venomous" implies that it will attack it you and cause major pain and/or paralysis.
Poison is a substance that is taken up by the victim, e.g., through the digestive or respiratory system. In the context of ecology, it is a defensive weapon. The term "poisonous" implies that it will make you sick or kill you if you eat it or inhale it.
So, snakes, spiders, wasps and sea anemones are venomous.
And, poison-dart frogs, millipedes and poison ivy are poisonous.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

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New Cat's Eye
Inactive Member


Message 10 of 13 (598044)
12-27-2010 12:37 PM
Reply to: Message 9 by Blue Jay
12-27-2010 11:52 AM


Re: Pet peeve
Its like The Caustic in D&D...
They're caustic but they deal ACID damage!?

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Taz
Member (Idle past 3291 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 11 of 13 (598049)
12-27-2010 2:20 PM
Reply to: Message 1 by Burnerjack
07-31-2010 8:54 PM


Burnerjack writes:
Can someone explain why some snakes are not poisonous while others have a most elaborate tool box with behavioral procedures for target identification et. al. Although not a philosophical question, I just have trouble surmising a simultaneous evolution of all the subsystems as well as why would some snakes have this capability and lose it. It would always be useful for enhanced species proppagation, would it not?
A long time ago, a member known as nemesis juggernaut pointed out while arguing against evolution that if natural selection was real then we would see species with a lot more beneficial characteristics. For instance, humans could always use wings to fly around when need be.
I suspect that what you're thinking of is along the line of why don't non-venomous snakes retain their venom because it's always useful, oui? I don't blame you for thinking this way.
I'm a backpacker, and sometimes I would spend days and weeks in the wild with my buddy. It's always a pleasant thought to have many things with me just in cases of emergency. I'd love to have at least a hand gun with me along with radios, meal packs, etc. There are at least a dozen things that I'd like to take with me. But you see, when you wander in the wild like I do, weight becomes an issue. Every little ounce counts. Why? Because every little extra ounce means I have to carry that much more weight on me while we climb the rockies or crossing the desert. Therefore, it is in every backpacker's interest to go through several times the stuff they will take with them to weed out all non-essential things. And even then, when I start my trek, I'd still have about 70-80 pounds of stuff on my back even after I've cut myself down to the bare minimum.
Now, try to apply this concept to biological systems. Every bio-chemical process costs energy. Having an extra pair of wings just for the sake of convenience costs energy! Having a bio-chemical process to produce venomous saliva costs energy! That's this much more energy the snake has to spend. Now, if the snake doesn't really need the venom, then wouldn't you say that it's wasted energy to try to keep producing the venomous saliva?
That's why we don't have a pair of wings or a tail. That's all just wasting energy.
Added by edit.
We see the same concern in engineering as well. Idealistically, we'd like a plane that could lift off vertically and fly horizontally once up at a certain altitude. When they first started drawing up engineering plans for such a plane, the biggest draw back to the engineers was the fact that the engine responsible for vertical ascend would be doing nothing but sitting there and waste precious fuel while the plane is flying horizontally. Why? Because it costs energy for the vertical ascend engine to be there even though it's not doing anything most of the time.
Idealistically, I'd like to see a plane that could go straight up, go horizontally, and also be able to dive into water and manuver about like a submarine. And I'm sure with enough mental exercises engineers can design such a vehicle. Why don't they make these very convenient flying/diving vehicles? Because large parts of the vehicle would be doing absolutely nothing but wasting energy most of the time. It will be extremely fuel inefficient.
Biological units go by the same general principles. Why have venom if it's just going to sit there most of the time wasting energy?
Edited by Taz, : No reason given.
Edited by Taz, : Changed day to they and larges to large in my sleep deprived state.

This message is a reply to:
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Taz
Member (Idle past 3291 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 12 of 13 (598060)
12-27-2010 4:00 PM
Reply to: Message 9 by Blue Jay
12-27-2010 11:52 AM


Re: Pet peeve
Bluejay writes:
So, snakes, spiders, wasps and sea anemones are venomous.
And, poison-dart frogs, millipedes and poison ivy are poisonous.
Speaking as an arachnid collector, I know what you mean. I frequently have to correct people on this as well. The most common question I always get from visitors is "are those tarantulas poisonous?" My answer's always "no, but they are venomous..."

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Omnivorous
Member
Posts: 3978
From: Adirondackia
Joined: 07-21-2005
Member Rating: 7.3


Message 13 of 13 (598074)
12-27-2010 7:42 PM
Reply to: Message 9 by Blue Jay
12-27-2010 11:52 AM


Re: Pet peeve
Thanks, bluejay.
I've always thought of snakes as venomous, things ingested as poisons, but I'd never thought about it in a rigorous way across all species--so I'm probably guilty of using them interchangeably.
My wife is an English professor. I shared your post with her, and she was equally delighted to learn this clear distinction in usage.
Now you have recruited two enemies of your pet peeve, one an agent inside the educational complex.

I know there's a balance, I see it when I swing past.
-J. Mellencamp
Real things always push back.
-William James

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