how does mutation lead to change in species and variation?

Answer 1

Here is how speciation mutation works (creating new species):

In the simple case one species is split into two groups who are unable to interbreed due to some barrier like a large river splitting up the habitat mice.

Mice in group A live in an area that is warmer, dryer and is abundant with soft fruit. Mice in group B live in a cooler area that is wetter and has lots of seeds.

Over time the mice will adapt to the area they live in by survival of the fittest. This is achieved because in each population there is variation in genes so some mice in a population would be better adapt to the new climates.

After a many generations:
The mice in group A will have shorter fir to keep them cool and conserve water and they would adapt their teeth to be come more efficient to eat fruit. Group B will have thicker fir to keep them warm and dry and their teeth would be better at eating seeds.

Over time the 2 groups may become too dissimilar to interbreed and then they can be considered two separate species. If they can still interbreed then you simply have variation in the species.

Answer 2

A mutation Happens when a problem occurs in the copying of DNA. These can help a species because for example with the peppered moth story (http://en.wikipedia.org/wiki/Peppered_moth_evolution) moths where being easily spotted when the trees changed, but becuase of a mutation that made them a different colour tmore survived becasue they were easily camaflagued. the lighter coloured moths that could be spotted died out because of being eaten by birds.But darker ones survived and then bred.

They then changed to darker coloured moths.

Hope this explains it a bit.

Answer 3

It involves switching one or turning off certain gene thus creating a difference in the protein that needs to be synthesize. Eg, certain animals have more gene like dogs but because certain genes are turn off, they cannot be on par with humans.