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Imagine a planet with the same climate all on the surface.

There is only one living creature on this planet (let's say a plant to avoid food problem). It is perfectly adapted for the climate. And as there is no herbivorous animals, there is no reason to evolve for defense systems.

In this case, would this plant evolve at all? There is virtually nothing to adapt or even to improve.

On the other way, if it doesn't evolve, would it lose its evolution capacity? In that case, if there is a change on the planet itself (a crisis like a meteor, or an orbit variation, etc), would it be condemned to extinction where an evolved creature would survive?

UPDATE:

I didn't think that how this situation came to exist matter, but it seems to be the case.

So let's say an alien civilization prepared this planet for this plant and implement it everywhere on the planet surface at the same time. They do it as an experience to see if the plant would evolve at all.

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    $\begingroup$ Evolution is all about changes be it good or bad, organisms thrive to mate, reproduce and pass down some of their genes to the next generation. Often stress is the driving factor to push evolution to take a specific path different from others and stress can come in many ways and forms. What you describe is a fantasy world much different from our dynamic world therefore feel free to omit evolution as you pleased. $\endgroup$ – user6760 Sep 22 '15 at 4:43
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    $\begingroup$ Does "single creature" mean "only one individual"? Does this single creature reproduce? If yes, there would be more than one. If no, how could evolution happen? (In fact, if it doesn't grow or reproduce, are we sure it's a life form?) $\endgroup$ – nikie Sep 22 '15 at 6:51
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    $\begingroup$ Your question doesn't make sense. Most definitions of life involve it reproducing, and anything that doesn't reproduce will quickly be outcompeted by others that do reproduce. Once you have reproduction and scarcity, evolution kicks in no matter how well adapted they are for the environment. $\endgroup$ – March Ho Sep 22 '15 at 9:10
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    $\begingroup$ You can see microevolution in a single beaker with a single strain of yeast (all cells clones) in the course of a few days. You will certainly have evolution in your planet. $\endgroup$ – Davidmh Sep 22 '15 at 10:23
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    $\begingroup$ I think an interesting counter-question would then be "What circumstances would be required so that evolution does not naturally occur?" $\endgroup$ – David K Sep 22 '15 at 16:32

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First off, notice that there would still be evolution if there's only a single species of plant on a planet.

For one, we have determined that the plant is perfectly suited for its environment. But what about in-species competition? A taller plant would have more access to sunlight. No? So if there's a genetic mutation in one plant that makes it slightly taller than the others, this plant would have more chances of survival and a long life span, which would make it more successful than the others and this useful trait would be carried on in its seeds' DNA and its offsprings' would be more successful than the next generation of other plants. And so on.

And then there is always some genetic variation present in a gene pool. Means that even within the same species, there is a slight difference of genetic information. For example, take us, humans as an example. There are humans living in the western hemisphere who are resistant to digestive disorders but are prone to respiratory diseases (like flu). In the eastern hemisphere we have humans who don't succumb to respiratory diseases easily but are very prone to digestive issues. So if (God forbid) a universal calamity hits the earth, only the people who are more resistant to it, will survive and the next generation would consist of only their children. Then, in the course of time, there would be some variation in their gene pool and ...

So yes, evolution is a constant process (at least in the current state of universe) and so far there is no way we can safely assume it will stop under any circumstances.

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    $\begingroup$ @Zack Thanks to random mutation, I'd think there would still be some variation. It would at first be much less common than you'd see in a typical crop, but it would still happen. $\endgroup$ – thanby - reinstate Monica Sep 23 '15 at 14:22
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    $\begingroup$ One big source of mutations is simple copying errors in DNA. Mistakes happen, and when they happen in germ cells (egg & sperm), they get passed on to offspring. $\endgroup$ – Kryten Sep 23 '15 at 14:28
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    $\begingroup$ I think this answer misses the point of the question: whether evolution depends on non-perfection. The answer is yes. If a system is already "perfect", then the mechanisms of evolution would be a waste, and if they existed, they'd be evolved out. Any mutation in a perfect organism is bad, so fitness would select against even the presence of mutable genetics. No sex. The scenario is not realistic, but... $\endgroup$ – markhahn Sep 23 '15 at 14:36
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    $\begingroup$ @MikeNichols The world may be perfect, and the plant may be what we would consider to be perfectly adapted for that perfect world, but the DNA copying errors would still possibly happen, which would make some plants have mutations. The world can be as perfect as you want it to be, but the plants could still "evolve" through these mutations because they have no control over what those mutations will be. $\endgroup$ – Zack Sep 23 '15 at 15:50
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    $\begingroup$ @Zack Yes, I'm aware that genetic drift fits under the former definition of "evolution" because it is a change in the DNA. But, the question didn't ask for the plant's DNA to be immutable. The question is clearly intended to address adaptive evolution and the role of natural selection. For the purposes of the question a definition of evolution that encompasses mutation and genetic drift is meaningless as all biological systems will have mutations. So, yes, the plant will change over time no matter what simply due to random chance, but selection will make sure those changes are meaningless. $\endgroup$ – Mike Nichols Sep 23 '15 at 20:07
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There's always something to improve. Every organism has two major concerns: the need for energy and the need for reproduction. If two organisms, even of the same species, are competing for the same resource (e.g., sunlight, food, water, land), then the more successful one will succeed.

In the case of photosynthetic plants, the organism that acquires more solar energy will succeed over the others. It has two good options: either grow taller than the other plants or grow larger leaves. In both cases, less successful plants find themselves in the shade with a diminished capacity to acquire the needed energy for their continued survival.

The successful plants remain around to reproduce, which passes on the successful trait to later generations and the unsuccessful trait fades away. Over time, the species evolves into broad-leaf and tall subspecies, eventually splitting away to form two new species that each fill a specific niche.

And the process continues...

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    $\begingroup$ “There's always something to improve.” Your whole answer hinges on this assumption. But the question asks about a perfect world i.e. nothing to improve. There are physical limits after all. At some point the only option are trade-offs. E.g. trading speed for reproduction. And I think those will hover around a stable point. $\endgroup$ – Michael Sep 22 '15 at 9:17
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    $\begingroup$ @Michael First of all, there is no such thing as a perfect anything in nature, so the question is a little incorrect to begin with. Second, nature doesn't maintain a status quot for long. Show me a "perfect" world and I will show you a world devoid of life. $\endgroup$ – Frostfyre Sep 22 '15 at 12:11
  • $\begingroup$ Downvoter: Care to explain? $\endgroup$ – Frostfyre Sep 22 '15 at 16:34
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    $\begingroup$ Evolution tends to find local maximums (optimums) and needs randomness (mutations) of various degrees to get out of them. After a long enough time (i.e. going through even the most improbable mutation if necessary) it will find the absolute maximum (perfection). Just play around with evolutionary optimization algorithms. On Earth environments (and thus criteria for perfection) change too fast, but “living fossils” apparently are so close to perfection for their environment that they haven’t changed over millions of years. $\endgroup$ – Michael Sep 22 '15 at 17:44
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    $\begingroup$ @Michael There's a difference to be made between an optimized specimen and a perfect specimen. An optimized specimen is ideal for its environment, but may fail to propagate. A perfect specimen is ideal for its environment and will never fail to propagate. $\endgroup$ – Frostfyre Sep 22 '15 at 18:10
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I find the question strange and am not sure if you fully understand how evolution works.

In this case, would this plant evolve at all? There is virtually nothing to adapt or even to improve.

Evolution doesn't happen with a goal or planned, it is a random process.

Every time the DNA of any living thing is recreated, when cells split etc. there is a small chance that errors happen. With a even smaller chance, this errors have effects. Reasons why the DNA mutates are numerous: Radiation, Toxines, Viruses, ...

If you define a perfect world as a world where such mutations don't happen, then there won't be any evolution.

If you say in your perfect world such errors happen, then there will be evolution.

As I said, evolution is a random process. You can't sit in front of your PC and decide "hell yeah, I am going to evolve today!" and suddenly you have three arms.

Evolution works this way:

  1. random errors happen and change parts of an organism
  2. this changes either give the organism some advantage or disadvantage in certain areas (usually a mix of both)
  3. if there is a disadvantage, the specimens with that mutation wont be able to compete with the "normal" rest and die after some generations
  4. if there is an advantage, they might take resources from the "normal" other plants without that mutation and maybe the others won't exist after some generations
  5. maybe there is a change that doesn't give any advantage or disadvantage, so both will continue to exist.

So for example, let's say there are different mutations that change the height to which the plant will grow. We have our "normal" plant A that is on your planet. Suddenly, two random mutations appear in two different plants. One, A+ will grow to 1.5 times the normal size. The other, A- will grow to 0.5 times the size.

As we know, plants mate and mix up their genes. So if two plants create a seed, we now say the resulting plant will have the height of both averaged.

After some generations, there will be plants in all sizes from 0.5 to 1.5.

But now think about this: All this plants need sunlight. But the larger plants will get more sunlight, while the smaller ones will stay in the shadow of the large plants. So the larger plants get more energy from the sun to grow even larger and "steal" more sunlight from the smaller plants. Also they can generate more blossoms and thus generate even more large plants stealing the light from the smaller ones.

So after some time, there probably won't be any smaller plants left and all plants "evolved" to be larger.

But maybe some plant has another mutation, that changes the colour of its blossoms. In this world, there is no difference at all between this two colours, so after some time there will be plants with both colours on the planet.

Also I don't see how a plant could lose its evolution capacity.

If you say your plant is perfect adapted, there can still be changes which make no difference like the different blossom colours. Even ignoring that, there will always be plants with mutations. If they are less adapted, they will just stop existing after some time, but at any given time there will be mutated plants on the planet.

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    $\begingroup$ You mean the resulting plants will have the height of both averaged? Surely not multiplied? Explain? $\endgroup$ – DSKekaha Sep 22 '15 at 18:43
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    $\begingroup$ "You can't sit in front of your PC and decide "hell yeah, I am going to evolve today!" and suddenly you have three arms." - of course that won't work, I can't change my own DNA and then force it to carry out the changes. But today I'm going to tell the Mrs, "Hell yeah, we are going to give our children superpowers!" I'm pretty confident it will work. $\endgroup$ – DoubleDouble Sep 22 '15 at 20:55
  • $\begingroup$ @DSKekaha yes, my mistake $\endgroup$ – Josef Sep 23 '15 at 6:36
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Both yes and no. As others have pointed out, even if there is only one species, they would still compete against each other. This would lead to some evolution.

I originally wrote: "However, it would be slow. What is driving most evolution on Earth is predator-prey and victim-parasite relationships." This turned out to be incorrect. After looking at various articles on Wikipedia, it seems that there are many other mechanisms that are more important. Some of these would be present on this planet, some would not. So, the rest of this answer should be taken with a grain of healthy sceptism. It is one possible scenario, but not the only one.

Plants would strive to be taller than the neighbours, but there are limits to that.

I would expect the species to find a local maximum and get stuck there. Very very rarely, some individual would get some combination of mutations that was better than this. This would make for a new burst of evolution until a new maximum was found. See Punctuated Equilibrium but with far fewer punctuations than is common on Earth.

It is possible that the new mutant would become a new species without out-competing the original, but not very probable. As long as it is only one climate on the whole planet, one variant would simply be best and win the whole world.

No species can lose the ability to evolve. As long as there are imperfections in the reproduction, evolution will happen.

However, species on Earth are to some extent "evolved to evolve better". This would be lost or never happen in the first place.

This sounds like bad news if there is a disaster of some sort.

It doesn't have to be. If there is a climate-related disaster, the species would be badly adapted, but as long as there are no competitors they would still be the "fittest". As long as everybody doesn't get utterly killed, survivors would still breed and reclaim the planet.

A biological disaster on the other hand would be much worse. I am thinking of a spaceship landing, bringing other species to the world. These are likely to kill off the natives in short order.

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  • $\begingroup$ Seems to me that the idea of "competition" requires a situation where there is some sort of struggle, or needs of multiple organisms whose situation puts them both wanting to take what the other needs at the same time/place, or something. That conflict of interest might or might not exist in a situation. Not every living thing is in conflict. In fact, most things aren't. Even animals in predator/prey relationships are rarely in survival competitions at a species level - it's usually more of a symbiotic relationship (q.v.) where if either out performs the other, both populations are in danger. $\endgroup$ – Dronz Sep 23 '15 at 16:59
  • $\begingroup$ " What is driving most evolution on Earth is predator-prey and victim-parasite relationships." - Citation needed. $\endgroup$ – Taemyr Sep 23 '15 at 21:23
  • $\begingroup$ I started looking for citations... and found that I was wrong. Sorry about that. Will edit. $\endgroup$ – Stig Hemmer Sep 24 '15 at 7:15
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There couldn't be just that plant alive - at least not without a major catastrophe. The plant itself exists because of evolution.

When life appeared, Earth was covered with purple bacteria. Then something happened, and one such bacteria found a way to produce energy from sunlight - that bacteria was green, and soon (ish) the Earth was covered with it: the genome of this green bacteria lives on to this day, billions of years later, in every single green plant that produces energy from sunlight.

For there to be a plant, there needs to be evolution. And in the time it takes for that bacteria to evolve into that plant, a gazillion other species have seen the light of day.

A planet with only a single species of a plant and no other life form whatsoever is unrealistic, I'm not buying it.

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  • $\begingroup$ I'm not obviously asking for a reality check, so how this situation happened is not really a concern... But if you insist: let's say an alien civilization prepared this planet and inserted this plant on all the surface in order to make an experience, $\endgroup$ – Aracthor Sep 22 '15 at 5:48
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    $\begingroup$ You tagged with evolution - I'm saying a single species and evolution contradict each other. $\endgroup$ – Mathieu Guindon Sep 22 '15 at 5:50
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    $\begingroup$ my question is precisely about the existence of a contradiction... If you think so, so just answer why. $\endgroup$ – Aracthor Sep 22 '15 at 5:52
  • $\begingroup$ Mat's Mug: Man this is a world-building site, so you are free to twist and turn the principles of our world and create a world that fits your desired phenomenon. So it's all right if there's a planet with just one plant type. You can read the question title as "Let there be a planet x, where only one species of plant exists. Will it undergo evolution or not?" It might help you focus on the scenario after the presence of this plant, not how that plant came into being. $\endgroup$ – Youstay Igo Sep 22 '15 at 6:12
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    $\begingroup$ A single species is not a stable situation anyway - any minor variations in environment (including the particular instances of same-species plants around you and their positioning) will have different suitability criteria, and we would expect any slight random genetic differences to get amplified over time, eventually resulting in speciation of the plant. Also, since these niches are empty and have no predators, we would expect some random cancer-like cell groups of the plant's own cells to eventually become a migrating parasite/disease; which can then evolve into various other microorganisms. $\endgroup$ – Peteris Sep 22 '15 at 8:12
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You don't have predators? Why wouldn't new predators evolve? As long as you can get more energy by attacking your neighbor than by playing the normal game being a predator pays off.

Your plants, as many have pointed out, are going to be evolving to out-grow each other. Trying to shade those around them so that they'll die and become extra soil nutrients or trying to smother them.

Imagine a gene which causes carriers to grow roots from branches touching other plants like ivy, now you have something which can use those around it for support to grow higher.

vine roots

Those genes become common but if they're too common in an area all the plants suffer because they need other normal plants to climb.

Now in the real world we have things like the vampire plant. Plants which can shove their roots/tendrils into other plants and feed on them directly.

http://www.pri.org/stories/2014-08-22/vampire-plant-even-more-nefarious-scientists-thought

Vampire plant

Now imagine that a new mutant gene in your ivy-like plant changes the roots to burrow into the flesh of the other plants to feed like they would into soil.

So now you have a world with a parasite/predator which feeds on your original species but is still closely related to it and can probably breed with it.

Which sets things up for a nice set of rounds of adaptions and competition for the parasites and the prey.

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1/ It seems possible to stop evolution !

There are lots of examples of earthlings species which evolution has stopped at a certain point, for example this bacteria living in the deep ocean has not changed since 2 billions years.

enter image description here

Add crocodiles, trilobites and other species. They found a place in nature that fits them so perfectly they (quite) stopped their evolution.

You could imagine a specie that stop evolving while finding the perfect balance, like my very old bacteria.

2/ Except it is not possible.

In fact, some species did evolve from these, but the original specie was not extincted as the new one did not replace them. These species seems freezed in evolution, but if they are so perfect, why don't they rule the world ?

They have a very specific place and climate they are adapted to. They don't spread worldwide. If they become too numerous, they die (from hunger and lack of vital resources).

I'm not sure how a unique plant could evolve and how climate could be the same everywhere, but let's assume that the case, you have the same plant everywhere, and the climate is... perfectly perfect. The plant grows. And grows. It spreads worldwide. Wow.

If nothing threatens your plant, then nothing stop it from growing. Your plant become its own ennemy : the nutrient the plant needs to grow will lack. The shadow from the grown-up plants will hide the sun from the youngs. Or, if it's perfectly flat, the place will lack for the youngs and nothing will replace an old dying plant on a ground without the essential nutrients (as the old plant has already deeply used it to grow)

As a result, the young plants will die, except the ones with a small mutation allowing them to accept another kind of nutrient, or less sunlight, or growing above the other. A new specie is born. Evolution strikes agains.

You could argue that the young plants can live from the dead old plants (That sounds creepy) but on earth, a lot of other species are needed to decompose a plant (worms, bacterias...). If the plant can "eat" herself still living or not decomposed, it will have a serious bad time with its "child", but that could be the one and only way your unique plant could rule the world, all alone.

And even with that solution, I'm not sure it's not already a new specie, as the first generation eats from the ground and the new generation eats froms the old plants, and might develop another way to absord nutrients.

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  • $\begingroup$ I can't find the latin or english name of the bacteria, it lives in the deep ocean nears sulphurous sources. $\endgroup$ – Tyrabel Sep 22 '15 at 15:28
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    $\begingroup$ If your bacteria (or other “living fossils”) can manage an equilibrium in their environment, why shouldn’t it be possible with a whole planet? $\endgroup$ – Michael Sep 22 '15 at 17:50
  • $\begingroup$ I'm not saying a specie have to evolve to survive on the whole planet, the plant I'm describing in my answer can colonize the whole world, but then ? When there is no place to grow anymore ? Even if the whole world has not a single change in climate, shadow or water sources, the plant will create inequality by growing, making shadow, eating the ground nutrients... And become a threat for itself that provoque an evolution. The plant might be dominant and unchanged, but not the only one specie in the world. $\endgroup$ – Tyrabel Sep 22 '15 at 20:01
  • $\begingroup$ Wikipedia suggests Desulfovibrio vulgaris is the best studied sulfer (or sulpher) "eating" bacteria $\endgroup$ – Foon Sep 22 '15 at 21:31
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Organisms make large sacrifices to their short term fitness to increase their long term, evolutionary fitness. The largest of these sacrifices is sexual reproduction. Sexual reproduction has long been a curiosity to evolutionary biologists because of how difficult it is. Plants go to great lengths, making flowers and fruits and buckets of pollen in hopes of reproducing. The predominant theory for why sexual reproduction is maintained is that it allows organisms to evolve and adapt more quickly through genetic recombination. A plant that didn’t require all of the extra organs and energy, and that could instead reproduce asexually, would be able to produce more offspring more quickly.

On your planet a plant that evolved to reproduce asexually would greatly outcompete its peers. On Earth such a plant would do well in the short run, but in the long run would lose out to its more adaptive competitors. But on a planet where the environment never changes and the plant is already optimized to a local maximum in fitness there would be no long term advantage to sexual reproduction. There are many plant species on Earth that have already taken this strategy. For most of these plants self-pollination has developed relatively recently, within the last few million years, which reinforces the theory that their strategy will lose out in the long run.

Based on the above I think it is possible that your plants may evolve to lose the ability to evolve to some extent. At the very least they are likely to at least stop devoting large amounts of time and energy to maintaining the ability to evolve. That isn’t to say the plants won’t still change over time. Geographic isolation and genetic drift will cause the plants to change and diverge very gradually. Even in different environments the plants will change in minute ways that won’t have any impact on their fitness, but will still make them different simply due to random chance. Eventually, unless the plants have some way of overcoming the reproductive isolation of having spread over an entire planet, speciation will occur.

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One thing that this question underestimates is the sheer massive size of planets.

Even if you seed a planet with a single species of plant perfectly engineered for the climate, even if the planet has the same climate on all the surface you still have to deal with things like topography and weather patterns.

A plant perfectly adapted for a particular climate still won't be adapted to different altitudes in the same climate. The plant won't do as well 10,000 ft up the side of the mountain as it will do at the base. Heck, just being on one side of a mountain, or in a valley, can make you have vastly different amounts of sunlight. Same climate, very different survival profiles for plants.

Weather patterns can and will cause different adaptations. If there is a prevailing westerly wind plants right near the coast would have their seeds blown out to sea, they wouldn't develop those helicopter styled seeds that get carried in the wind. They will develop heavier, sturdier seeds that ill either not fly away into the sea, or, that can survive the sea. OTOH, plants on the other side of the coast will have an advantage to having flying seeds.

Boom! That's speciation in the works.

In places like the rainforests, there are species who have filled a niche that is only several feet across. You take a couple of steps, and it can't survive in this new, different, environment. There is just no way to curate an entire planet to such a degree where there are no niches to fill with evolutionary advantages.

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  • $\begingroup$ The question explicitly posits a planet with uniform climate. $\endgroup$ – markhahn Sep 23 '15 at 14:42
  • $\begingroup$ Even with a uniform climate, the rain may always fall on one side of the mountain. $\endgroup$ – Biff MaGriff Sep 23 '15 at 20:20
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The "No-Evolution-Case"

There might happen to be a "living creature" with a DNA-Code that is impossible to mutate. This would make accidental changes of the DNA-Code impossible. If there is no "other" DNA-Code around that could mess up the original code during the reproduction cycle, than there is no evolution.

Lets assume the DNA-information of the creature is hardcoded into a never changing material. This could have happen during some material mistake while teleportating. Or the creature could have been made by humanity! Or... the creature was incidentally created during the first moments of the universe, when there was this "Bang" that we all believe in. Lets further assume the rest of the Body of this creature is totally fine with not having DNA made of nucleic acid (see: DNA).

Wouldn't this still be a living creature -- eating, sweating, doing its thing?

The answer is YES.

even through reproduction there would be no change in the DNA, because all possible mates carry exactly the same data set!


But is evolution maybe the wrong concept for describing the change/development of a species? Could this described species possibly evolve from generation to generation, if it had the ability to think, feel and communicate, plus had a good memory? -even if it cannot change any DNA-Data?

The answer is YES - it must evolve, but this is apparently no "evolution".

"Evolution is change in the heritable traits of biological populations over successive generations." Wikipedia

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  • $\begingroup$ Even if you could somehow make immutable DNA, that doesn't preclude evolution. The creation of new cells is, by definition, a mutable process. So any change in that process can change the physical interpretation of the base code. $\endgroup$ – MichaelS Sep 23 '15 at 4:07
  • $\begingroup$ @MichaelS cells were not mentioned in this possibility, just DNA. Virus also have DNA and they reside inside cells. $\endgroup$ – Armfoot Sep 23 '15 at 17:25
  • $\begingroup$ It doesn't matter what you call it. Any kind of lifeform requires a mutable portion. If it can't change, it's not alive. The parts that change have to "read" the DNA in order to replicate. The parts that read the DNA can mutate even if the DNA can't. That mutation can cause the unchanged DNA to be interpreted differently, which is the same basic result as mutating the DNA itself. $\endgroup$ – MichaelS Sep 24 '15 at 1:47
  • $\begingroup$ @MichaelS you're trying to grasp another subject, but hey, here are some hypothesis to stop mutation. You may explain it throughly in there why mutation cannot be stopped in living beings, enjoy! $\endgroup$ – Armfoot Sep 24 '15 at 15:59
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Evolution is not a binary flag that either occurs or does not occur. It occurs in varying degrees, no matter how perfect the world is, until it is truly perfect. Not in the sense of "oh, there's no predators or climate," perfect in the sense of "no random noise, completely laminar airflow, and in general no unpredictability at all." If an individual or species can successfully predict the effect of every single molecular collision for all time, it can elect to escape evolution entirely. Otherwise, there is some unknown factor, and some regions of the species will naturally get selected over the others. For one thing, this involves a perfect method of reproducing any genetic material (however "genetic material" should be specified in such a case). This is only thermodynamically possible if the DNA is a crystal at absolute zero (which is impossible in the known universe).

However, one might be able to drive evolution asymptotically towards zero effect, but not zero. It may be possible to continuously increase the predictive capacity of the individual/species until you can ensure that any random perturbation will diminish in effect fast enough that the system can never leave a "basin" of perfection. This certainly would not look like anything you or I would call life.

What might it look like? Using the concept of "basins" in highly unpredictable systems, one can visualize it. The idea is that any perturbations must get distributed evenly across the entire planet fast enough to attenuate it before it causes a change. Mythbusters showed a beautiful effect with metronomes which I would argue does a good job of showing the kind of feel you should expect from a basin such as this. (N-Sync) (32 metronome synchronization)

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This species would be at a serious risk of dying out.

As others have pointed out, there's a good chance the species would slowly diversify by simple random changes, but if there's another option to consider: Genetic drift.

enter image description here

Consider a species with two traits for which there is no evolutionary pressure. Let's say they're colored blue or red, and the color has absolutely no effect on their lives in any way. In that case, the proportion of red or blue creatures in the population would be a simple random process. A simple random process like this will eventually, purely by chance, lead to a situation where the whole populatation is one color, at which point the other color will be dead. The ability to have the other trait is simply lost forever.

In your world, as you have painted it, there is pretty much no evolutionary pressure on any traits. If that situation is maintained, and the plants don't manage to diversify their own environment, they would converge towards a planet-wide monoculture. At that point the smallest microbe, solar flare, climate change etc would wipe the whole population out in no time.

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There is only one living creature on this planet.

Making the assumption that there is only one individual organism, and that perfect means that it is invincible (also from starvation).

Then you are basically describing a rock. ;) And since no reproduction is taking place there will be no evolution.

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Your scenario is talking about 1 single organism, not a species. Evolution is about species, descendants, etc. There cannot be evolution for an individual organism. The organism is either suited for the environment and lives or is not suited and dies.

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  • $\begingroup$ Yes, but over time, the organism may reproduce; evolution will decide how its descendants survive. $\endgroup$ – HDE 226868 Sep 22 '15 at 23:01
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Imagine a planet with the same climate all on the surface.

It would be extremely unlikely to have a planet whose surface was exactly the same everywhere. It certainly wouldn't be naturally occurring. There would have to be "sunlight" from every direction equally. There couldn't be any airflow or water currents, density variation in the planet, planetary rotation, elevation changes, lakes, rivers, clouds, or any number of other things. You'd also have to eliminate external factors, such as gamma ray bursts, meteorites, or just random dust from space.

There is only one living creature on this planet (let's say a plant to avoid food problem).

Does it reproduce? If so, there would quickly be more than one plant.

If not, there are a few problems. First, it's going to die if it's remotely like Earth-life. So it won't evolve, it will just go extinct.

Second, a plant isn't one living thing. It's trillions of them, called cells, that reproduce constantly. Supposing the plant has a naturally-indefinite lifespan, those cells would eventually evolve and either destroy the host plant (that's what cancer is), or turn it into something new. The cells could evolve into distinct microbes which could, in turn, spawn entirely new forms of life.

It is perfectly adapted for the climate.

Anything that survives in an environment is "perfectly adapted" if it's the only thing around. The plant could always adapt to get bigger and use more sunlight, or adapt to get smaller and waste less energy. Without other things putting selective pressure on it, no particular adaptation is more or less "perfect" than another.

Furthermore, that plant is changing its own environment. Metabolism creates waste products which will eventually alter the climate by significant amounts. The planet will eventually run out of geothermal energy. The energy source for the artificial sunlight will die. Nothing is forever. In a more plausible scenario, planetary changes will cause ice ages and global warming as a matter of course.

On the other way, if it doesn't evolve, would it lose its evolution capacity?

If it doesn't evolve, it doesn't evolve an inability to evolve.

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Over population of the species could be a reason that the environment is not perfect. There could be evolution of another species better fitted to this environment. Then even though the planet does not change more evolution can occur as the species compete with each other and with themselves. It may settle down but it could just keep changing for ever.

It may be that evolution does not occur. For example there could be something that keeps the population low (and any genetic changes do not confer any advantage so they do not propagate), so there is no competition between members of the one species. (But even if a genetic change has no advantage it could still spread through the population (on average to 50% but any change could spread more due to statistical variation)).

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I think it was in The Beginning of Infinity where David Deutsch gave an example illustrating how evolution can not converge to the ideal state. Take an island with a certain fruit growing on it and an animal that needs that food to survive. At a certain point in the seasonal cycle, the fruit is edible, but it is not ripe, so the animals won't get the most energy out of it. This is the only factor affecting population size, hence the population size is now at it's maximum (this is basically your perfect state).

Assume the animals have adopted to only eat the fruit when it is ripe. Now a genetic modification takes place in one animal which causes it to eat the fruit earlier. It will probably outperform the others because it gets to the fruit earlier and there is no population pressure. This means less food for the others, so the total population size will decrease.

So, after a couple of generations, those animals with the mutation will consume more to stay as healthy as the others which leads to less food for those without a mutation. The old population will die out over a couple of seasons. Note how the population size has decreased now because there is less energy available!

Now, another mutation turns up... and the whole process repeats.

This is all very theoretical, but it goes to show that evolution isn't quite survival of the fittest. You can change the story above a bit and even create nice loops where the end state is exactly the state you started with. Don't think of evolution as an end-of-the-line model, always converging. It is not.

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