Gene Pool

The gene pool of a particular species means the set of the diversity of the entire genes present in that population is called the gene pool of that population. The gene pool gives information about the total genetic diversity of a particular population.

Gene Pool Centers

Gene pool centres refers to areas on the earth where important crop plants and domestic animals originated. They have an extraordinary range of the wild counterparts of cultivated plant species and useful tropical plants. Gene pool centres also contain different sub-tropical and temperate region species.

Major Gene Centres:

Russian Biogeographer “Valvilov” identified the following major gene pool centers on the earth:

The following centers are :

South American Gene Center : ( 7000 Bc-3000 BC):
- Starch-rich plants originated such as Sugarcane, tomato, cotton, cocoa, tobacco, etc are believed to be originated here.
- Centre: Peru, Chile, Brazil, Paraguay.
South Mexican and Central North American Gene Centre :( 3500 BC):
- Areas: Mexico, Panama, Coastal Rica,
- Plants: Cocoa, Pumpkin, cotton, sweet potato, tomato, etc are believed to be originated here.
Mediterraneab Gene Center : ( 4000 BC);
- Wheat, lagune, algae, and cabbage are believed to be originated here.
South West and Middle East Asian Gene Center : ( 8000-6000 BC):
- Oats, apples, Wild barley, and wild wheat are believed to be originated here.
- Greece, Egypt, West Asia.
African Gene Center : ( 5000 BC):
- Areas around Nile valley.
- Animal: Sheep, Goats, Swine are believed to be originated here.
- Plants: Legume, Barley, Millet, Indigo, etc are believed to be originated here.
Indian Gene Center : ( 9000BC)
- It has two parts:
  - Indus valley gene center
  - South and South Asia gene center:
    - It spreads from Pakistan to Southeast Asian countries.
Central Asian Gene Center : ( 4000 Bc -3000 BC)
East Asian Gene Center : ( 6000-5000 BC) or Chinese and Japanese gene Center.
- Cucumber, Cabbage, pea, walnut, sugarcane, etc are believed to be originated here.

Importance of preserving Gene Pool:

Gene pool represents the total number of genes found within a population, those populations with larger gene pools tend to have more genes, and hence, more genetic diversity.
Each gene has a specific purpose, such as giving the plant/animal a particular characteristic, resistance to a disease, tolerance to harsh climate, and so on. Therefore, a population with a larger genetic diversity will be better prepared to deal with disease outbreaks or extreme environmental changes, because they will, most likely, have those genes that protect them from such adverse changes.
On the other hand, populations with a lesser number of genes in their gene pool will be susceptible to such problems, which may cause them to become endangered or even perish altogether, i.e., become extinct. Therefore, populations with a large gene pool will have more chances of survival, while those with small gene pools are in danger of acquiring genetic diseases, deformities, and infertility.
FAO estimates that in the last century, about 75 percent of crop genetic diversity was lost as farmers worldwide switched to genetically uniform, high-yielding varieties and abandoned multiple local varieties.

Examples

Humans

As a single species, humans can interbreed anywhere on Earth. Therefore, every allele of the roughly 19,000–20,000 human genes in our DNA contributes to the human gene pool.

Butterflies

At locus one, there are two alleles in a population of butterflies. Homozygous individuals (two copies of the same gene) for the recessive allele lack eyespots, but those with the dominant allele possess eyespots on their wings.
If an allele that produces eyespots mutates and is favoured by natural selection, eyespots may reappear in the population. Alternately, if members of the original butterfly population mate with members of another butterfly population that carries the trait for eyespots, eyespots can reappear through gene flow.