genetic mutation

[vincentfromyay]

...generation to the next?

 

i understand, in principle at least, how the eye might have evolved from something that very slightly resembled an eye, such as a tiny light sensitive area on a single-celled organism; but i'm struggling to imagine how the said organism could have gone from having no eye at all to having the 'proto-eye' in the first place.

 

i believe that this came about due to random genetic mutation; but am i right in thinking it came about in just one generation? isn't the 'proto-eye', the tiny light sensitive area (or whatever the proto-eye may be) itself vastly complex, relatively speaking? and isn't it a lot to believe that this could come about due to the mutation or mutations occuring as the result of one organism "giving birth" to another

 

(if even this early process was the result of lots of mutation over lots of generations, then the first mutation/s would have to be advantageous, so i'm guessin that this first mutation/s is considered as the one/s that led to the 'proto-eye', yeah?)

 

i haven't studied biology formally, so please bear with any glaring errors here. thanks.

[DevilSolution]

 

(if even this early process was the result of lots of mutation over lots of generations, then the first mutation/s would have to be advantageous, so i'm guessin that this first mutation/s is considered as the one/s that led to the 'proto-eye', yeah?)

 

 

 

nah man, its very improbable to be the first mutation, other mutations which arent advantageous would die off so the given species which evolved an eye had a greater chance at survival.....i imagine life itself has some intricate connection to the electro magnetic spectrum so thats how life evolved to have senses. without them life in all its forms would be pretty pointless

 

i believe evolution is backwards though, the mutations subtract genetic material not add...... i have no proof other than the observable

[Halucigenia]

how significant can a mutation or mutations be from only [one] generation to the next?

Mutations only have to occurr for them to be able to be passed from one generation to the next. However, they only have to be significant enough to give some kind of survival or reproductive advantage to enable them to increase in frequency within the gene pool to facilitate evolutionary change if that is what you are getting at.

 

i understand, in principle at least, how the eye might have evolved from something that very slightly resembled an eye, such as a tiny light sensitive area on a single-celled organism; but i'm struggling to imagine how the said organism could have gone from having no eye at all to having the 'proto-eye' in the first place.

As you stated, it only had to be initiated by a tiny light sensitive area. For organisms to function successfully within an environment they have to be able to react to their environment in some way or other, the ones that react successfully survive and go on to reproduce. Any slight advantage in being able to detect electromagnetic radiation - heat and light for instance, that enables them to gain more nutrients, avoid predators etc. will be promoted by evolution. To go from having no eye to having an eye may seem like a large leap but thinking about having no sensory capability to having a slight sensory capability effected by a small molecular change that gives a large advantage to survival or reproduction would seem, to me, to be a small enough step to be much more probable.

 

i believe that this came about due to random genetic mutation; but am i right in thinking it came about in just one generation? isn't the 'proto-eye', the tiny light sensitive area (or whatever the proto-eye may be) itself vastly complex, relatively speaking? and isn't it a lot to believe that this could come about due to the mutation or mutations occuring as the result of one organism "giving birth" to another

All a mutation is, is a small change to the genetic material of an organism from one generation to the next so in that respect mutations are always effected in one generation. However, it is better to think of evolution as a population phenomenon i.e. those mutations that arise between generations need to spread within a population over many generations of organisms for evolution to proceed. Evolution is about fixation of mutations in the gene pool within a population.

That change from less sensitive to more sensitive detection of electromagnetic radiation being of slight benefit to the individuals that possess the mutation compared to those that don't is all it takes for this mutation to increase in frequency toward fixation over the generations. It does not have to be "vastly complex" as many molecules are photosensitive to some degree all it takes is for them to undergo a chemical reaction in the presence of light and that this chemical reaction be detectable by the chemistry going on within the cell(s) of an organism.

 

(if even this early process was the result of lots of mutation over lots of generations, then the first mutation/s would have to be advantageous, so i'm guessin that this first mutation/s is considered as the one/s that led to the 'proto-eye', yeah?)

Well, everything starts with the first step. Individual steps are small but all that is necessary is for these small steps to be possible to be able to travel long distances.

 

i haven't studied biology formally, so please bear with any glaring errors here. thanks.

No worries, hopefully I can help you think it through.

 

nah man, its very improbable to be the first mutation, other mutations which arent advantageous would die off so the given species which evolved an eye had a greater chance at survival.....i imagine life itself has some intricate connection to the electro magnetic spectrum so thats how life evolved to have senses. without them life in all its forms would be pretty pointless.

I'm not quite sure what you mean by "its very improbable to be the first mutation" but see my explanation above. Your statement "other mutations which arent advantageous would die off so the given species which evolved an eye had a greater chance at survival", however, is not a bad summary of how evolution is proposed to proceed.

 

i believe evolution is backwards though, the mutations subtract genetic material not add...... i have no proof other than the observable

You are, however, way off base with this statement. It is in fact observable that mutations, other than deletions and substitutions, actually add genetic material. As mutation is defined as a change in genetic material any change other than a deletion or substitution is by definition is an addition.

Also, even though a a mutation may subtract genetic material this subtraction can affect the genome into producing novel adaptations which can then effect evolution.

So your assertion that evolution is backwards (whatever that is supposed to mean) is not supported by your claim that genetic material is subtracted not added by mutation.

[DevilSolution]

I'm not quite sure what you mean by "its very improbable to be the first mutation" but see my explanation above. Your statement "other mutations which arent advantageous would die off so the given species which evolved an eye had a greater chance at survival", however, is not a bad summary of how evolution is proposed to proceed.

 

You are, however, way off base with this statement. It is in fact observable that mutations, other than deletions and substitutions, actually add genetic material. As mutation is defined as a change in genetic material any change other than a deletion or substitution is by definition is an addition.

Also, even though a a mutation may subtract genetic material this subtraction can affect the genome into producing novel adaptations which can then effect evolution.

So your assertion that evolution is backwards (whatever that is supposed to mean) is not supported by your claim that genetic material is subtracted not added by mutation.

 

well its just unlikely that the first of any mutation will be beneficial, this is what i meant by "its very improbable to be the first mutation", hence why dinosaurs pre-date humans...

 

 

its quite simple what it means, we dont evolve we devolve.

[Halucigenia]

well its just unlikely that the first of any mutation will be beneficial, this is what i meant by "its very improbable to be the first mutation", hence why dinosaurs pre-date humans...

I think that you are misunderstanding the context of the point about the "first mutation" there.

vincentfromyay stated:-

(if even this early process was the result of lots of mutation over lots of generations, then the first mutation/s would have to be advantageous, so i'm guessin that this first mutation/s is considered as the one/s that led to the 'proto-eye', yeah?)

Clearly meaning the first mutation in a sequence of mutations that lead to the development of the eye.

Not what you seem to be alluding to - the very first mutation ever. Is that in fact what you mean?

If any prior mutation to that first mutation in the sequence was not beneficial in that respect it it is not what vincentfromyay, I think, is alluding to. However, see below.

 

Anyhow, whether any mutation is beneficial or not depends on the environment that the organism that it finds itself in is in. So there is no clear cut definition of a beneficial mutation. It is quite true that the majority of mutations are not beneficial but neutral and a lot are also detrimental. However, even neutral and detrimental ones can go on to be increased in frequency within a population especially if you consider dominance and recessiveness between alleles. So if circumstances change these less than beneficial mutations can go on to become beneficial under different circumstances.

Also, the first mutational step towards any novel trait need not be immediately associated with that trait itself, it could be something that gives benefit in one way that then is co-opted for another use later in the evolutionary sequence.

 

its quite simple what it means, we dont evolve we devolve.

You still have nothing to back this often repeated (by creationist types) claim up.

[Edtharan]

well its just unlikely that the first of any mutation will be beneficial, this is what i meant by "its very improbable to be the first mutation", hence why dinosaurs pre-date humans...

 

 

its quite simple what it means, we dont evolve we devolve.

If you only look at a single mutation, then yes, it is extremely improbably that it will be beneficial. But, if a single mutation is beneficial, then it is more likely to be passed on (because that organism will be better at surviving).

 

Also, the chain of mutations that lead to a specific trait don't only effect that trait. They often have many other effects with the organism. One such is light sensitivity. This can be the by-product of other traits. The chemicals in our eyes are similar to many other chemicals that are used for other tasks, such a chlorophyll (and other too).

 

So the leap from no eye to proto-eye was not such a big leap as the chemicals used in the proto-eye would have had some other function, but then a slight mutation caused the organism to produce a slightly different chemical (which became refined over millions of years to more efficient chemicals).

[Halucigenia]

well its just unlikely that the first of any mutation will be beneficial, this is what i meant by "its very improbable to be the first mutation", hence why dinosaurs pre-date humans... its quite simple what it means, we dont evolve we devolve.

Thinking again about what you posted I will have another go at understanding what you are implying (never mind that fact that I think that you are misunderstanding the context of the point about the "first mutation").

 

By “the first mutation” do you mean that from an arbitrary starting point in time the first mutation to arise in a population from that point in time will be unlikely to be beneficial?

If so, then, yes, that is obviously true as beneficial mutations occur less frequently than detrimental or neutral types of mutations. It’s just that the beneficial ones are the ones that tend to get promoted due to natural selection. However, (and this has really been puzzling me hence the return to this comment) even if that is true why would you think that this has anything to do with dinosaurs pre-dating humans and why would you think that this means that organisms are devolving?

 

According to my understanding of what evolutionary theory proposes dinosaurs pre-date humans because evolution from the dinosaur’s common ancestor predates the evolution of all mammalian forms from the mammalian common ancestor .

 

While mammals and dinosaurs do have a common ancestor, that is even further back in time than both of their respective common ancestors.

 

The respective lineages will have generated different mutations and these different mutations will have been promoted due to natural selection acting on the different mutations that were beneficial in different ways under different circumstances in the separated gene pools. Therefore the mutations that arose and have remained in the respective lineages over time since that original common ancestor of both dinosaurs and mammals are mainly those that have been beneficial within those respective lineages. There is no definitive reason why dinosaurs should have had to pre-date humans, it’s just that the contingencies of these different lineage’s different mutations appearing at different times resulted in the dinosaur common ancestor evolving before resulting in the evolution of the mammalian common ancestor, that’s all.

 

Furthermore, these mutations, because of the many splits and divergences along the way, constitute an accumulation of genetic differences through time. This accumulation of genetic difference through time is what we term evolution and goes to show that organisms are evolving not devolving (whatever you intend that to mean).

 

If this bears any relation to what you are claiming and aids your understanding of the apparent misunderstandings you have of what evolutionary theory proposes please let me know.

Edited February 13, 2012 by Halucigenia

[questionposter]

well its just unlikely that the first of any mutation will be beneficial, this is what i meant by "its very improbable to be the first mutation", hence why dinosaurs pre-date humans...

 

 

its quite simple what it means, we dont evolve we devolve.

 

Exactly. The first step most likely isn't a step forward, that's why evolution takes millions of years and why we have these eyes only after millions of years.

[Xittenn]

Just a quick note to the OP, I think the evolution of phototaxis is an emergent property of early photosynthetic Prokaryote and Protist algal species. This makes sense in terms of researching the evolutionary pathways--as mentioned earlier--as photosynthetic species both require light to function as well as are already equipped to harness light in some fashion. An interesting point here is that the proto-eye that I believe you are referring to occurs in Prokaryote species in a region of their structure that connects to their flagella; the butt end. This sensor enables motor function in the relevant direction towards light in what is termed phototaxis. In terms of evolution of animals phototaxis is already an observable emergent property of organisms and cells in particular, so incorporating this into their makeup would simply be a matter of it's continued use as an adventigious property. The development of the eyeball would simply be an ongoing set of mutations that occurred during cephalization that would protect the eye, broaden sensitivity of spectrum, as well as increasing resolution, focus and restriction. Interestingly enough, I believe the Rotifer has the same adaptation of a proto-eye attached to their flagella as does the Prokaryote species'. These are microorganisms that are classified within the Kingdom Animalia and not Kingdom Prokaryote and an example can be seen in the picture that is my avatar. I am however making conclusions on the matter based on small pieces of information I have picked up here and there and will have to at some point complete a more in-depth study on the subject.