how evolution occurs in a population?

Answer 1

Evolution depends on three things:
VARIATION, SELECTION and HEREDITY.

Variation means that not all of the individuals in a population are the same: some will be faster, some stronger, some will be better at conserving heat, some will be able to hold their breath longer ... and so on. This variation is introduced because of mutation.

Selection is what happens when some individuals in the population, because of their variations, are slightly better at surviving and at breeding. So in a cold environment, the ones with better heat conservation will be a little better off, and will have more offspring.

Heredity is the idea that offspring will inherit the traits of their parents. So the offspring of the individuals with better heat conservation will inherit this ability.

I'm sure you can see from this example, that after several generations, the proportion of the population with better heat conservation will rise, as they have more offspring, and the others have less. The population has *evolved*, as it is now different from how it was.

Answer 2

First off lets define evolution. Taking a common definition from various biology textbooks we can say that evolution is the change in the frequency of alleles in a given population over time. Now, with that definition we can add in natural selection. Just to broadly define natural selection we can say that in nature there are genes or alleles that are beneficial to the reproduction of those who posses it, thereby giving them an advantage over others. If there is allele X and Y, and Y gives the advantage, then the frequency of X should diminish given what we have defined. Since we have a change in the frequency of alleles in a given population over time, we have observed evolution due to natural selection.

Answer 3

If you have a homozygous recessive gene and say, you mate with someone who has a homozygous recessive gene. Your kids will all be homozygous recessive for the gene. If all of your kids do the same thing you did.... and their kids did the same... your entire family tree would be homozygous recessive for that gene. You can apply this to populations too. Population can evolve simply by mating patterns like I just mentioned. You could compare it to how often irish people have red hair. There is a good chance that they all have red hair because that was just he mating pattern many years ago. Red hair mated with red hair for generations.

Answer 4

Evolution occurs because of mutation, and is also effected by natural selection, geographic and reproductive isolation and other factors.

Answer 5

Mutations, natural selection and eons of time.

...however, evolution never did and doesn't occur although most people beg to differ. Evolution simply didn't happen, not enough evidence supporting it and too much contradicting it. Evolution = bull malarky.
However, my answer up there is what most evolutionists would tell you.