It was getting long for a comment: A species that was originally parasitic, but then evolved to survive independently of its host by independently evolving the same metabolic functions A predator that originally relied on its prey to synthesise some vital metabolite, but later evolved the ability to produce the missing metabolite for itself through a similar pathway A parasite is generally evolved from a free living form. It has a reduced genome and cannot synthesize many vital nutrients. It is unlikely that it would acquire a gene that would enable it to live freely. A parasite, in general does not require to synthesize nutrients; so it is not under any pressure to acquire that function as long as its host is surplus. Same is in the case of predators. Basically, in higher organisms it is difficult to conjure a new gene; it is a slow process and happens via gene modification. However, in evolution - Are there known examples where an evolved mechanism "echoes" one originally provided by the environment? - Biology Stack Exchange By using our site, you acknowledge that you have read and understand our Cookie Policy , Privacy Policy , and our Terms of Service . Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It only takes a minute to sign up. Sign up to join this community Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top Are there known examples where an evolved mechanism “echoes” one originally provided by the environment? post-LUCA) cell were originally provided by an external mechanism, in the form of abiotic chemical processes that took place in some very specific microenvironment, and evolution eventually provided a solution that very closely echoed the one that had originally been provided by the environment. Point (1) seems relatively easy to satisfy in an evolutionary scenario; it's point (2) that I'm specifically interested in. The two most popular hypotheses in the field both have this form: Some forms of the The RNA-World hypothesis hold that originally, RNA nucleotides were produced by purely chemical processes in the environment, and that life evolved from self-replicating RNA molecules made up from these abiotically-produced monomers. Later, life evolved a cellular metabolism by which it could construct its own RNA monomers. This satisfies point (2) because it says that the environment provided RNA rather than some other heteropolymer with catalytic properties; the evolutionary solution echoes the environmental one in that it uses the same complex molecule. Wächterschäuser's Iron-Sulphur World theory, and many of its descendants, including Russel's alkaline vent theory , hold that the reductive tricarbolic acid cycle (rTCA cycle, aka reverse citric acid cycle) was originally catalysed by mineral surfaces. This enabled the formation of the first cells, which eventually evolved enzymes that could be used to catalyse the rTCA cycle without the mineral catalysts. This satisfies point (2) because it says that the first evolved solution used essentially the same chemical pathway as the one provided by the environment, just with different catalysts. (Not all hypotheses in origins of life have this form. For example, although the treehopper Cyphonia clavata mimics the outward appearance of an ant, it does so not by being anatomically similar to an ant but by having a face on its butt .) Consequently I'm looking for known examples from evolutionary biology that satisfy both point (1) and point (2). That is, I'm looking for examples where a species originally relied on some relatively complex process in its environment, and became less dependent on its environment by evolving a mechanism that closely echoes the one originally provided by the environment . An example that might fit the bill would be a species that was originally unable to produce a key metabolite (e.g. I'm asking for examples (if they exist, which they may well not) of metabolic functions which at one time were provided by the environment but which are now performed by the organism using a similar molecular mechanism. It's not a particularly easy thing to make clear, but I will have a think about how to do it better. $\endgroup$ – Nathaniel Dec 30 '14 at 13:16 $\begingroup$ @Nathaniel well, by pathway I meant that a newly acquired function plugs itself in the network an expands the pathways. But by endosymbiosis new networks can also be incorporated (thats what I meant there). But for your question I guess the answer is - almost every gene. I'm not just asking for examples of the evolution of metabolic pathways. I'm asking for examples (if they exist, which they may well not) of metabolic functions which at one time were provided by the environment but which are now performed by the organism using a similar molecular mechanism. Examples would likely come from phylogenetics, rather than direct experimental observation. $\endgroup$ – Nathaniel Dec 30 '14 at 13:17 add a comment | 2 $\begingroup$ See this more as a comment than an answer, since it became too long for a comment. However, I think some of the examples should be relevant to refine your question. This could maybe also help explain why the " ...evolved solution 'echoes' the one provided by the environment ". At the moment I don't understand at all why this should be the case in general. Adaptive evolution happen because of selection that acts on differences in fitness, and it is indifferent to whether the mechanism echoes a previous solution to a similar problem (except for the fact that evolution is constrained by the evolutionary history of organisms). share | improve this answer | follow | answered Jan 4 '15 at 23:03 fileunderwater fileunderwater 15.7k 3 3 gold badges 45 45 silver badges 86 86 bronze badges $\endgroup$ $\begingroup$ Thank you for the answer.