Question of the Week- 1/20/2016

Jan 19, 2016

This week’s question comes from Mark C who asks, “[Hypothetically] if a group of scientists conducted artificial selection over millions of years, could they take an organism and selectively breed it into any other organism? A question of genetic potential (a cat to dog, yeast to chimp), are there any limits to the ‘direction’ evolution could take? Are there circumstances in the evolution where no further genetic adaptation is possible?”

Our winner will receive a copy of Richard Dawkins’ “An Appetite for Wonder”!

21 comments on “Question of the Week- 1/20/2016

  • here we go again 🙂

    “Is there an evolutionary explanation as to why some groups seem more particularly prone to take life and give their own lives in deference to their religion?”

    “some groups seem [] prone”

    the key word here is “seem” – It is the person(s) to whom it seems that you should be looking at – who is perceiving this? On what sort of scale are we to measure this? Are we to accept that someone who hardly has any education or background knowledge of these “groups” and who gets all their information from Fox News is justified in making such an assumption?

    These groups you allude to – are they doing these actions they are “prone” to in isolation? Are they people living a happy secular life with their kids at university and they and their friends enjoying a BBQ suddenly likely to say “I know, let’s go and kill a bunch of people for our God!” Maybe they are in the middle of some hell-hole that we created where our high-tech soldiers and mercenaries on huge budgets patrol and indiscriminately kill and abuse people? Maybe they are children of people who have lost everything in years and years of war and abuse? Who exactly are these people “prone” to doing these things?

    “prone” you suggest? Prone? You mean that’s built into them and not built into us?

    I think the question is horrid – it’s racist, it’s reinforcing a disgusting meme that has become part of the world view of far too many people.

    It’s lending “scientific” legitimacy to the wrong question for the wrong reasons.

    Better to ask: “is there an evolutionary explanation for why an arbitrary group of humans attacks and destroys another group of humans?

    or

    “is there an evolutionary explanation for why some ape species exhibit violence both within and between groups”

    or

    “is there an evolutionary explanation for why animals kill?”

    pop



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  • @OP – if a group of scientists conducted artificial selection over millions of years, could they take an organism and selectively breed them into any to any other organism?

    They could probably NOT breed it into a pre-existing organism, but parallel and convergent evolution, and repeated independent re-evolving of similar organs, (eg. multiple versions of the eye), or similar forms, indicate that similar but not identical paths are possible.

    https://en.wikipedia.org/wiki/Evolution_of_the_eye
    The evolution of the eye has been a subject of significant study, as a distinctive example of an analogous organ present in a wide variety of taxa. Complex, image-forming eyes have evolved independently some 50 to 100 times.[1]

    Complex eyes appear to have first evolved within a few million years, in the rapid burst of evolution known as the Cambrian explosion.

    In extremophile plants, many body forms closely resemble each other in the Cactacae, Euphorbiacae, Stapeliae and Pachypodiums. Several individual species closely resemble each other across the groups which are not closely related.
    http://davesgarden.com/guides/articles/view/2149/

    A question of genetic potential (a cat to dog, yeast to chimp), are there any limits to the ‘direction’ evolution could take.

    Within the vertebrates the variation is body form is considerable.
    http://www.shsu.edu/~bio_mlt/Chapter3.html
    Even challenges of radical differences, such as internal V external skeleton can be met in for example, turtles!

    yeast to chimp,

    Fungi and Primates and both from the Eukaryotic branch of the tree of life, but that goes a very long way back.

    Are there circumstances in the evolution where no further genetic adaptation is possible?”

    Isolated island ecosystems, illustrate evolutionary radiating branching diversity where the opportunity presents itself, but some forms of cloned asexual reproduction or parthenogenesis, may lack the adaptive mechanisms https://en.wikipedia.org/wiki/Parthenogenesis on which selection pressures can act.



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  • Hey PoP, you seem to be stuck on a previous question.

    This one looks just as silly, though. Yeah, let’s breed a crocoduck. But to answer it, look at what’s actually happened: breeding from wolves to dogs of all kinds, from the Irish Wolfhound down to the Pekinese. That was all artificial selection, and didn’t take all that long on the evolutionary timescale.

    But “yeast to chimp”, seems a bit overambitious.

    First off, recognise that all currently existing lifeforms are like distinct leaves on the one tree, the Tree of Life, let’s call it. So you’re not going to get from one of them to another by any kind of breeding programme, selective or otherwise. What you are going to get, if you try, is a bunch of new and different leaves that never existed before.

    Look back in time, that is, follow the twigs, branches, boughs, back towards the trunk of the Tree of Life, and where these meet (moving backwards) you find the common ancestors of different sub-branches.

    Somewhere in there is the common ancestor of all mammals, including cows and cats, dogs and dolphins, but not chickens, that’s a different branch, and a much earlier common ancestor. From that perspective, there is no theoretical reason why you could not start with any existing species of mammal and selectively breed their offspring for different conditions, over millions of generations, and get a dolphin-like branch as well as a cow-like, cat-like and dog-like branch. After all, the overlap in DNA between all mammals is a very high percentage (which someone, maybe Alan, can quote quite accurately).

    If you look at mammals, there are indeed more similarities than differences. The skeletal structure is one example, all have four limbs, each made of one bone, two bones, lots of little bones, digits. As do the skeletons of every animal descended from the fish that came ashore – crocodiles and ducks too.

    I suppose crocoduck is a possible outcome from genetic manipulation, though what you’d get from editing together genes from these species might be hard to predict. Crocs with feathers, perhaps, but also lots and lots of nonviable creatures. You’d need a good deal of patience, and a detailed understanding of which genes do what, to “create” a duck with some crocodile features, or a crocodile with some duck features.

    At least, whatever they were, they’d still have the common skeletal layout of their common ancestor.

    Stranger than the crocoduck is the recent work to insert spider genes into goats. You might imagine the result as something far scarier than the spiders in The Hobbit, but it turns out to be just goats that have some spider silk in their milk, very useful.



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  • [Hypothetically] if a group of scientists conducted artificial selection over millions of years, could they take an organism and selectively breed [it] into any… other organism?

    Hypothetically, yes.

    …are there any limits to the ‘direction’ evolution could take[?]

    Only those imposed by the laws of physics.

    Are there circumstances in the evolution where no further genetic adaptation is possible?”

    If conditions are favorable to life, and mutation can occur, then no.



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  • If scientists were to breed an intelligent life-form which was adapted for space travel, there are many examples of organisms on Earth which are already much better adapted and more resilient than humans.
    Many are more tolerant of impacts and high G-forces, while others are much more resistant to radiation.
    Yet more have capabilities such as hibernating or remaining dormant (as individuals or eggs) for extended periods, which would permit extended flight times without heavy demands on life support systems.



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  • Hi Mark,

    Given that you allow for millions of years, and artificial selection – which in today’s World must surely include genetic modification – it seems obvious that we could produce all sorts of organisms. In principal we could, therefore, produce new species that are, in all important respects, just like another existing species.

    What a colossal waste of time.

    In the future (as you envisage humans living for millions of years) we will probably, occasionally, produce organisms without using an existing one as our starting point. The science on this advanced greatly in recent years. The reason we won’t always start anew is that genetic engineering from an existing organism gives us things like protection from diseases and auto-breeding. If it ain’t broke, don’t fix it.

    The idea anyone would want to use cats to breed dogs is fantastical nonsense. It seems to me that this is a creationist’s question?

    … are there any limits to the direction evolution could take.

    For evolution via selective breeding, many: Funding (incl. questioning likely returns on investment), moral objections, safety concerns, time constraints, resource limits and probably others …

    Example: Evolution via artificial selection is limited by the genetic starting point. Without genetic engineering we have to pressurise the breeding subjects repeatedly (and if they go extinct, which is likely to happen many times, start again) until suitable genetic changes arise (descent with modification) and to do this seems likely to cause great distress. Such experiments with animals are unlikely to pass an ethical review.

    For evolution via natural selection: The limits are in the environment. This is why more than 99% of species that have ever lived are now extinct. When we think of biological evolution the environment, the ever-changing environment, is the unforgiving master. Any creature that cannot deal with an environmental change is doomed. Those that can handle change thrive.

    Of course, descent with modification may not evolve the experimental subjects in the desired way. Just like natural selection, artificial selection produces many blind alleys.

    Are there circumstances in the [sic] evolution where no further genetic adaptation is possible?

    No; at least, I’m not aware of any.

    Evolution happens whether we intervene or not, all the time. Attempting to breed for a certain trait cannot control for natural selection or genetic drift. These things can and will really mess with your experiment – constantly. Millions of years may not be enough, and the main reason is that you have a specific end result in mind.

    Yeasts, cats and apes are the way they are due to environments that drove the evolution of their ancestors. Those environments no longer exist, and would have to be created / simulated. In effect, even using artificial selection would require that you build an ecology and selectively breed a very large number of species in parallel (including things like viruses) in order to achieve the necessary selection pressures. This is not a practical proposition.

    From the above we can see that, although it is possible in principal to selectively breed from yeast to an ape-like species, in practice it is exceedingly improbable because natural selection will continue to do its own thing, because of the huge resource requirements and because nature is chaotic.

    It is such a highly improbable scenario that, practically, it’s impossible – even given millions of years.

    Peace.



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  • If a group of scientists conducted artificial selection over millions of years, could they take an organism and selectively breed it into any other organism?
    Part 1: No, the current species are an expression of millions of years of evolution. We could produce parallel species and see how they fare.
    Part 2: Yes, if DNA building could be started up from the eukariote cell with synthetic DNA. Seems an enormous waste of time and resources to replicate what nature has already done
    Part 3: Who can determnine what would be desirable in species millions of years from now? I can’t even predict what will happen tomorrow
    A question of genetic potential (a cat to dog, yeast to chimp), are there any limits to the ‘direction’ evolution could take?
    If you work with current species, then there are limits imposed by the current DNA, but the genus offers lots of possibilities

    Are there circumstances in the evolution where no further genetic adaptation is possible?”
    I don’t think so; it’s not just the species evolving, but also the environment, which, in turn, drives further evolution, artificial or not.



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  • Very unlikely, a cat cannot be turned into a dog by selective breeding. Selective breeding selects certain characteristics which are in the gene pool already and which suit a domestic purpose instead of survival in nature. For example in nature a strong dog with an aggressive temperament might have better chances of survival and reproduction than a timid dog. He might lose his life in a silly action, but dogs are herd animals and hunt together. In mating he certainly will be superior and therefore he will be more likely to pass on his genes than the timid dog.

    In artificial selection for the purpose of breeding a pet dog good for children, the timid dog would be preferred and measures would be taken to give him the chance to procreate. Out of his litter the most timid dog might be selected again for further breeding and so on until these dogs become very different from their wild forefathers and mothers. This process uses genes which are in the gene pool already. Significant achievements are possible over just a couple of generations.

    However, to breed cats from dogs would involve mutations (unless, of course all cat genes are already present in dogs and just have not found expression in the phenotype yet, which I believe is extremely unlikely). In other words to achieve this genetic engineering is required. The genes of the dog must be changed, and then selected in a second step. Today scientists can implant genes into other organisms. For example it is possible to implant the gene for the production of insulin into bacteria, which is very useful in fighting diabetes. These bacteria are a new species with a different gene pool than their parent cells.

    To replace the dog genes by cat genes would be very difficult and at present impossible using the above mentioned method. However, one could try to just expose dogs to nuclear radiation and change their genes that way. It would be pretty cruel, but thus is nature. Most dogs would probably just die of cancer, many others would just become infertile and an extremely tiny amount would produce changed living offspring. Even amongst those it is very unlikely that the new gene thus produced is actually a cat gene. Now this is just for one gene, think of all the genes that are different between cats and dogs. So the answer is most likely not and if yes, it would probably take millions of years to achieve this.

    Regarding the second question, is there a final stage where no further adaptation is possible, the answer is a conditional yes. Yes under the condition that there is no change in the environment and most likely it will concern just few genes. For example an animal might be able to very convincingly have the same colour and pattern as the bark of the tree on which it lives. Then there can be no further improvement in the genes involved in producing this for as long as there is no environmental change.



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  • 10
    petermetric says:

    A cat and a dog have a common ancestor. So to produce a dog from a cat one would need to “devolve” the cat back to the common ancestor and then, of course, producing a dog is clearly possible by natural evolution, which could in principle be simulated.

    The question remains is “devolution” possible, i.e. can devolution be controlled by evolutionary means. I think, ultimately, this makes the process untenable in general, even given millions of years. On the other hand Inverting the principle of survival of the fittest, which is clearly evident in dog breed selection, gives one paws for thought.



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  • Since we are talking about artificial selection, the only factor that we should consider is the probability of all genetic differences from both living beings be overcome by mutations that will be transmitted to their descendents.
    This probability is not null, but is very small. So it can happen, but it will probably take a long time.

    Evolution has no limits, and there is also no perfect or completely evolved creature. Selection only dictates whom is able to live long enougth to make descendents. For nature no crature is better then other, as long as a individual can survive and reproduce it’s species is adapted



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  • can devolution be controlled by evolutionary means

    Bear in mind, the question involves evolution by artificial selection. If the proposed hypothetical were possible, what you refer to as “devolution” (as a reversal of evolution) would (might) not be necessary, and in a sense is conceptually nonsensical. The common ancestor of cats and dogs can be thought of as a “devolutionary” product, in hindsight, only because evolution into cats and dogs actually happened. A shorter (or longer, but at least different) path from dog to (effectively) cat is certainly conceivable.



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  • 14
    petermetric says:

    Hi Luisa and Doug, you may well both be right – no limits. But I have a reservation based on entropy. It is possible that all the molecules in a room could spontaneously end up in within one cubic cm but essentially with a probability of practically zero. Entropy can fluctuate but on average it always increases. I feel that a similar principle may well apply in evolutionary processes and I would hazard a guess that to evolve a dog FROM its common ancestor with a cat would take far shorter a time than to evolve a dog TO this common ancestor. If I am corrected on this then I would simply move the goal posts and talk about common ancestors further back. In brief I think there may well be a principle that inhibits significant devolution. I am happy to be corrected on this!



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  • Hi petermetric, I might have miss understand you, but it seems to me that you think that a dog, for example, has bigger entropy than its ancestor and I can’t see why. Looking for a dog and a amoeba, for example, I belive the ameba has a bigger entropy.The dog is much bigger and more complex.
    Any way, I still don’t agree with your argument, since the law you mention about entropy is only applied to closed systems, which is not the case.



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  • 16
    petermetric says:

    Hi Luisa, I do not mean to imply that entropy plays such a simple role in evolutionary processes (Dog=big entropy, amoeba=small entropy) – though it must be a key player. I agree with your comment about closed systems- the sun is a massive source of low entropy. However, I do suspect that “evolving” an ape into an amoeba is impossible, even in principle, as each phase of its “evolution” would have to be massively micro managed. If this is the case (any experts here?), my guess is that the second law of thermodynamics will lie at the heart of it.



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  • petermetric
    Jan 27, 2016 at 5:50 am

    However, I do suspect that “evolving” an ape into an amoeba is impossible, even in principle, as each phase of its “evolution” would have to be massively micro managed.

    It may not be as hard as you imagine!

    Apes, like all mammals, begin as single cells after fertilisation, so to evolve into an independent single celled organisms, they would have to switch off the genes for multicellular development, and restore any lost ancestral genes from their single celled distant ancestors which permitted life as single cells.



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  • 18
    petermetric says:

    ok, but to provide a sequence of environments that select this over and over again down to one cell – that is where the expensive micro management comes in.



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  • Are there circumstances in the evolution where no further genetic adaptation is possible?”

    I would say, “Yes”.

    I have an idea that during some period of creation in earth’s history a whole host of genetic blueprints were formed. This is a natural period of creation, not a God given one. It seems logical to me that when the conditions were right for the creation of life, a host of variations were created at the same time. There may well have been more than one location and more than one time when this occurred and the conditions for creation of life may have persisted for a long period.

    The evolutionary idea of a sea creature lumbering on to dry land and developing lungs seems quite plausible but my argument does not see the sea creature as an animal that follows one line of evolution eventually ending up as homo sapien but as an animal that will follow the line of evolution determined by the particular genetic blueprint it carries. Yes, we all came from a sea creature like that, but only the ones that were genetically human to start with.

    The evolutionary tree, or evolutionary trees, that map the development of each species are probably quite correct and there is no need to worry about where the extra genetic coding came from as the animals change from one species to another. The genetic code was always there. It was just waiting for environmental conditions to be right for it to be able to move the animal further along on its evolutionary path.

    This idea provides a solution to Darwin’s dilemma, as the sudden appearance of complex life forms during the Cambrian explosion does not need an ancient history of Darwinian type evolution to get from simple life forms to the complex ones found in the fossil deposits. The genetic codes for the complex life forms already existed within the cells of the first simple animals and just needed the right conditions to be brought to expression. The fact that we are here at all needs a scientifically acceptable explanation.

    According to my hypothesis, Darwinian evolutionary trees are best interpreted in reverse. By selecting any animal, anywhere on the tree, we can track its developmental progress back to its simplest form. The backwards path will cross a junction at some point where it intersects with the backwards path of another animal. This does not mean that the animals are related even if some of their ancestors had a similar external morphology. They may have looked the same but they were different species and could not have produced any offspring. By following the evolutionary tree backwards it is possible to follow each animal along its own unbroken genetic line back to its cellular origins

    Two major things served to cement my ideas. First, the axolotl and its amazing ability to survive to reproductive maturity as an axolotl or to develop further and become a salamander when the environment is right for it to change. Second, the embryonic similarities of different species whereby you have the same looking embryos or ‘animals’ carrying different genetic blue prints and which go on to become completely different animals. Of course, this starts off at the cellular level where every cell is just a cell but each will develop only along the line determined by its genetic blueprint.



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  • @john-hamling

    It seems logical to me that when the conditions were right for the creation of life, a host of variations were created at the same time.

    There are only around 7 major life forms today. The Burgess Shale had over 30. Almost all of these lines went extinct.

    Cambrian explosion

    There was no sudden explosion during the Cambrian period. It’s a myth. This is more instructive of the time scales and that evolution continued at a slow and steady pace.

    [W]e now know that the “explosion” took place over an 80 m.y. time frame. Paleontologists are gradually abandoning the misleading and outdated term “Cambrian explosion” for a more accurate one, “Cambrian slow fuse” or “Cambrian diversification.” The entire diversification of life is now known to have gone through a number of distinct steps, from the first fossils of simple bacterial life 3.5 billion years old, to the first multicellular animals 700 m.y. ago (the Ediacara fauna), to the first evidence of skeletonized fossils (tiny fragments of small shells, nicknamed the “little shellies”) at the beginning of the Cambrian, 545 m.y. ago (the Nemakit-Daldynian and Tommotian stages of the Cambrian), to the third stage of the Cambrian (Atdabanian, 530 m.y. ago), when you find the first fossils of the larger animals with hard shells, such as trilobites.



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  • John Hamling #19
    Mar 1, 2016 at 4:54 am

    Are there circumstances in the evolution where no further genetic adaptation is possible?”

    I would say, “Yes”.

    The evidence from genetics says no! Evolution is an on-going process which can be observed, providing the correct time-scale is used. All organism throughout history have shown adaptation to changing conditions – or have died out as a result of failing to do so.

    I have an idea that during some period of creation in earth’s history a whole host of genetic blueprints were formed. This is a natural period of creation, not a God given one.

    There is no evidence of this in either the genetic or the fossil record.

    It seems logical to me that when the conditions were right for the creation of life, a host of variations were created at the same time.

    None of the experiments or evidence on abiogenesis support this. All the evidence shows a gradual build up of complexity as adaptations to environmental changes and opportunities.

    https://www.youtube.com/watch?v=U6QYDdgP9eg
    The Origin of Life – Abiogenesis – Dr. Jack Szostak

    There may well have been more than one location and more than one time when this occurred and the conditions for creation of life may have persisted for a long period.

    Indeed there may have been many places, and could have been more than on example of abiogenesis, but only the descendants of LUCA survived to evolve into all the modern forms of life.

    https://en.wikipedia.org/wiki/Last_universal_ancestor

    The evolutionary idea of a sea creature lumbering on to dry land and developing lungs seems quite plausible

    Evolving branches of various groups of sea creatures made the transition to land via beaches or swamps. Some branched into prawns and insects, going their separate ways. Those with backbones evolved into fish, amphibians, reptiles and mammals.

    Some modern fish such as Mudskippers, Lungfish, Walking Catfish, and Eels can still come out of water on to land, demonstrating this transition.
    There are also plenty of fish walking around the sea-floor on fins!

    http://phenomena.nationalgeographic.com/2014/01/13/how-we-got-on-land-bone-by-bone/

    but my argument does not see the sea creature as an animal that follows one line of evolution eventually ending up as homo sapien but as an animal that will follow the line of evolution determined by the particular genetic blueprint it carries.

    There is no predetermined paths or objectives in evolution. Evolution takes small steps as opportunities present themselves.

    Yes, we all came from a sea creature like that, but only the ones that were genetically human to start with.

    There was no specifically human DNA in our fish ancestors. Geneticists have mapped the DNA which is shared with other organisms. It all starts with LUCA, but mutations and additions and deletions are accumulating all the time, as they have been for millions of years. Natural selection sees that there are small successful adaptations, with any damaging or less competitive variations dying.
    Only the successful survivors continue to produce offspring!

    http://genetics.thetech.org/online-exhibits/genes-common

    The genetic codes for the complex life forms already existed within the cells of the first simple animals and just needed the right conditions to be brought to expression. The fact that we are here at all needs a scientifically acceptable explanation.

    Only part of the expressed genetic code pre-exists, but is added to by accumulating unused random mutations. When these random mutations are later expressed, most will be damaging or fatal to the individual offspring, but most organisms produce many off-spring so a few fatalities simply weeds out expressed damaging mutations, while the beneficial ones become the successful breeders, increasing their numbers. The changes are unlikely to be identical in different locations so branching into new species occurs in separated populations.

    That is the scientific explanation Darwin found.

    According to my hypothesis, Darwinian evolutionary trees are best interpreted in reverse. By selecting any animal, anywhere on the tree, we can track its developmental progress back to its simplest form.

    This is a path showing progressive changes evolving as the expressed DNA changes branching an forming new species.

    The backwards path will cross a junction at some point where it intersects with the backwards path of another animal.

    That would be the point where shared DNA was in a common ancestor before the were branches separated. – perhaps separated geographically, as with species developing independently, when cut off from the original population on isolated islands.

    This does not mean that the animals are related even if some of their ancestors had a similar external morphology.

    The DNA analysis clearly shows that they are related.

    They may have looked the same but they were different species and could not have produced any offspring.

    “Species” is an arbitrary human system of classification. Evolution and evolutionary branching is a continuous process, so the inability to cross-breed is a progressive loss of ability to produce fertile offspring, NOT a sudden cut-off. Lions and Tigers have been on different continents for millennia, but can still produce cubs which are Ligers and Tigons!

    By following the evolutionary tree backwards it is possible to follow each animal along its own unbroken genetic line back to its cellular origins This leads to a long succession of common ancestors. For example, all animals with backbones have common ancestors. The closely related ones have more recent common ancestors.

    Second, the embryonic similarities of different species whereby you have the same looking embryos or ‘animals’ carrying different genetic blue prints and which go on to become completely different animals.

    The variations in “genetic blue-prints” are quite small in related species. Much of the variation in development, is just Hox genes switching on or off other genes, at different points in embryonic development.
    With the Axolotl it can survive as the juvenile form, similar to its ancestor, or switch on the genes which evolved later, to develop further and become a Salamander.



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