How can evolution be defined and measured by the frequency of alleles in a gene pool?

Answer 1

It's not gene pools that have a frequency, but allelesthat have a frequency in the gene pool.

Alleles are "rival" variants for the same gene. For instance, if hair colour is coded by one gene, then brown hair may be allele A for that gene, while blonde hair is allele B for the same gene.

Imagine people as being packages of genes, each containing two full sets of genes (humans are diploid, so we contain two copies of genes in all our cells - but they may be two different alleles for the same gene). Now put the contents of all those people-packages together in one pool: that's your gene pool.

The more people have some trait T, coded for by allele A of gene G, the higher the number of copies of allele A will be in the gene pool. That's what's called the allele frequency.

Answer 2

There are four ways I know of that the frequency of alleles in a gene pool can change over time.

1. natural selection - If one organism has an allele that is beneficial to the survival of the population it will become selected for and will be mated with. Over time the amount of offspring with this gene/allele will increase while other genes that were not selected for because may decrease.

2. genetic drift - By chance one organism may not mate during the mating season or they die. For whatever reason the organism doesn't pass on their gene and so, especially if this gene is rare, it may decrease the frequency of this allele in the gene pool or make it extinct all together. Smaller populations are more susceptible to genetic drift as it causes their allele frequencies to fluctuate more dramatically.

3. population bottleneck - Due to some chance occurrence such as an environmental change a large majority of the population dies. The alleles from those that survive may not necessarily represent the alleles from the larger population and some alleles could have been wiped from the gene pool resulting in a change in the allele frequency.

4. - Founder effect - A small portion of a larger population is removed and repopulates itself in a different environment. The alleles of the small population don't necessarily represent the alleles of the larger population and so may not have alleles that were present in the larger population. This also changes the allele frequency

Answer 3

Evolution is a change in the ratio of dominant to recessive alleles (for a trait) from generation to generation.

Answer 4

Relative frequency describes the number of times a particular allele for a gene occurs in a gene pool.

Answer 5

By sampling the population and testing whether or not the allele is present for each individual within your sample space. The larger the sample, the more accurate your estimate will be.