Natural selection and speciation

[gracy]

How natural selection leads to speciation?Speciation is a process of making a new species ,right? Natural selection just select one organism from a bunch of organisms of the same species to survive ,so how does it leads to creation of a new species?For example in an area covered with snow ,white rabbits from a bunch of rabbits(brown,as well as white rabbits)are more likely to survive and therefore reproduce ,so after some time white rabbits will be more in numbers but how this lead to a creation of new species?White rabbits were present even before this natural selection ,natural selection has not created any new species.How natural selection can change DNA ?As different species can only be created if DNA is changed enough that it can't interbreed with previous species to produce fertile offspring.

 

[Bystander]

For example in an area covered with snow ,white rabbits from a bunch of rabbits(brown,as well as white rabbits)are more likely to survive and therefore reproduce ,so after some time white rabbits will be more in numbers

Overlap the high snow area with an area of less snow cover and let the total of the two areas be the range of the original single rabbit species. Then let 3,000 generations of rabbits select for white rabbit survival in the high snow area, and for brown rabbits in the low snow area. You eventually get enough accumulated difference that there are now two species occupying the range formerly occupied by one; one, white, more suited to high snow cover, and the other, brown, better fit for survival in the portion of the original range with low snow cover.

 

[gracy]

White rabbit and brown rabbit are members of same species ,right?

 

[Bystander]

After 3,000 or so generations selecting between high and low snow cover, they are no longer the same.

 

[gracy]

let the total of the two areas be the range of the original single rabbit species.

original single rabbit species,including both brown and white rabbit,right?

 

[Bystander]

Yes.

 

[gracy]

white, more suited to high snow cover,

That means initially only because of white color (no other characters different from those of brown rabbits)white rabbits survived in that area which was covered with snow but after 3,000 or so generation we will get completely different different enough to be called as of different species .Because the white rabbit would now develop very much other characters different from that of brown rabbit or even different from initial white rabbit foe eg it my develop more hair i.e it may become more hairy to adapt according to snowy environment.Right?

 

[Bystander]

You've got the idea. None of us live long enough to actually see it happen, but that's one of the speciation mechanisms.

 

[gracy]

OK.Can you please explain how white rabbits develop characters that are better suited for snow areas?There Should be mechanism for this .In which sideheading(topic) we learn this in biology?

 

[Bystander]

That should be hiding in the index somewhere under "chance or random mutation." Beyond that, there's not a whole lot that's known.

 

[gracy]

That should be hiding in the index somewhere under "chance or random mutation." Beyond that, there's not a whole lot that's known.

So only because of random mutation,i suspect this.Because why would random mutation would be so well targeted,i mean how these mutations because of which white rabbits develop characters that are better suited for snow areas can be called as random mutations.As these mutations are not random it appears to have a purpose of providing characters that are better suited for snowy areas.

 

[Bystander]

There are as many mutations that are unfavorable to survival as there are favorable. The unfavorable cases don't survive. "Targeted" mutation is NOT a factor. You can look up Lysenko, or Lysenkoism as examples. Bottom line is that just because you want to be taller, you can't make yourself taller, or able to digest cellulose, or become photosynthetic. It's just sheer dumb luck that your ancestors mutated the directions they did, and that those mutations didn't kill their descendants.

 

[gracy]

I am asking
white rabbits became new species because it was more adapted /showed characters which suited for snowy areas.How they showed characters which suited for snowy areas?
Your answer -Random mutation
My objection-How this can be random ?As this mutation appears to have a purpose of providing characters that are better suited for snowy areas.
Your answer on this ?

 

[Ophiolite]

Rabbits are prolific breeders. In every generation of rabbits there will be many mutations. Most of these will be neutral, many will be harmful, but one or two may confer a benefit. These are then more likely to be passed to the next generation and potentially spread throughout the population.

Thus, there is no targeting, except that the environment targets and tests every mutation. It ignores the neutral ones, discourages the negative ones and selects the positive ones.

 

[gracy]

There are as many mutations that are unfavorable to survival as there are favorable. The unfavorable cases don't survive. "Targeted" mutation is NOT a factor. You can look up Lysenko, or Lysenkoism as examples. Bottom line is that just because you want to be taller, you can't make yourself taller, or able to digest cellulose, or become photosynthetic. It's just sheer dumb luck that your ancestors mutated the directions they did, and that those mutations didn't kill their descendants.

Oh!I got your point after reading ophiolite post.Thanks again.

 

[gracy]

Rabbits are prolific breeders. In every generation of rabbits there will be many mutations. Most of these will be neutral, many will be harmful, but one or two may confer a benefit. These are then more likely to be passed to the next generation and potentially spread throughout the population.

Thus, there is no targeting, except that the environment targets and tests every mutation. It ignores the neutral ones, discourages the negative ones and selects the positive ones.

Thanks.

 

[Medicol]

There are rabbits with some special genes on to expose their endurance to cold winters. These will mate randomly with others to create a new population that also has these "enduring" genes. Other less enduring animals do not necessarily die out as what the phrase "selection of the fittest" may suggest, they may i.e migrate or move gradually to other areas and mate with dark or brown rabbits to produce new generations of warmer blood and pigments on their body parts to exhibit the specialties of tropical beauties. Overtime, a whole new species which best matches with surrounding conditions appears. That is also when a new branch on the tree of life comes into being.

 

[mfb]

You've got the idea. None of us live long enough to actually see it happen, but that's one of the speciation mechanisms.

We don't live long enough for the rabbits, but for E. Coli (in an artificial environment) we do.

 

[Doug Huffman]

You've got the idea. None of us live long enough to actually see it happen, but that's one of the speciation mechanisms.

See the Hardy-Weinberg Law and genetic drift rate.