In this article, You will read Major Gene Pool Centres for UPSC (Biogeography Notes).
Gene: The gene is the basic physical unit of inheritance. Genes are passed from parents to offspring and contain the information needed to specify traits. Genes are arranged, one after another, on structures called chromosomes. A chromosome contains a single, long DNA molecule, only a portion of which corresponds to a single gene. Humans have approximately 20,000 genes arranged on their chromosomes.
Gene pool, the sum of a population’s genetic material at a given time. In simple terms, A gene pool is the collection of different genes within an interbreeding population. The term typically is used in reference to a population made up of individuals of the same species and includes all genes and combinations of genes (sum of the alleles) in the population.
It represents the complete genetic diversity found within a population or species.
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 subtropical and temperate region species.
- Population – All of the inhabitants of an interbreeding species, within a particular place at a particular time.
- Natural Selection – The process in which organisms that are able to adapt to their environment are able to survive and reproduce, while those which cannot adapt, do not survive or reproduce.
- Genotype – The genetic makeup of an individual organism.
- Phenotype – The observable characteristics of an individual, determined as a consequence of their genotype.
Major Gene Pool Centres
A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity can cause reduced biological fitness and an increased chance of extinction.
The centre of origin is a geographical area where a group of organisms, either domesticated or wild, first developed its distinctive properties. Many authorities believe centre of origin are also centers of diversity. But at the same time, many scientists argue that it is almost impossible to assemble meaningful information on the origin and evolution of certain crops as the evidence dims and fades away with each passing year.
The first person to pose the question of the geographic origin of cultivated plants was Alphonse de Candolle. Based on the evolutionary concepts of Darwin and taking the findings of Candolle as points of departure, the Russian scientist Nicolay Ivanovich Vavilov developed his hypotheses on the centers of origin of cultivated plants in the early 1920s.
Vavilov Gene Pool Centres
Vavilov assumed that most of the main agricultural species could be traced back to one particular region, which would be its centre of origin. Furthermore, he assumed that these centers would be common for a range of crops and that such regions could be universal centers of origin and of type formation, i.e. genetic diversification.
One of Vavilov’s first findings was that it was possible to distinguish between primary and secondary groups of cultivated plants. The primary crops were the basic ancient cultivated plants that were known to humanity only in their cultivated state (e.g. wheat, barley, rice, soybeans, flax, and cotton). The secondary crops comprised all the plants that were derived from weeds that infested the primary crop fields and were found to be useful on their own (e.g. rye, oats, and false flax).
The region of maximum variation, usually including endemic types and characteristics, could also be the centre of origin. The centers of origin would, as a rule, be characterized by many endemic variable traits and could comprise characteristics of entire genera. Within the centers of origin, Vavilov determined so-called foci of type formation of the most important cultivated plants i.e. hearts of the centers with regard to genetic diversification and type formation.
Whereas Vavilov’s principles were strengthened throughout the period of empirical investigations, the numbers and borders of the centers of origin of cultivated plants changed continuously. In the end, he suggested the following centers of origin of cultivated plants.
For crop plants, Nikolai Vavilov identified differing numbers of centers: three in 1924, five in 1926, six in 1929, seven in 1931, eight in 1935, and reduced to seven again in 1940.
Vavilov centers of origin:
In 1926 he published “Studies on the Origin of Cultivated Plants” which described his theories on the origins of crops. Vavilov concluded that each crop has a characteristic primary center of diversity which is also its center of origin. Eight areas were recognized and suggested as centers from which all of our major crops were domesticated. Later, he modified his theory to include “secondary centers of diversity” for some crops.
- (2A) Southern Chile,
- (2B) Paraguay-Southern Brazil,
- Middle East,
- Central Asia,
- China and Korea
World centers of origin of cultivated plants
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 disease, tolerance to the 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.
Having recourse to genetic material is however essential to adapt and improve agriculture in the face of threats, such as diseases or warming climate that can alter growing conditions. For example, a variety of Turkish wheat, collected and stored in a seed gene bank in 1948, was rediscovered in the 1980s, when it was found to carry genes resistant to many types of disease-causing fungi. Plant breeders now use those genes to develop wheat varieties that are resistant to a range of diseases.
Medicine: Many medicines are obtained from plants/animal sources like Neem oil, Quinine from Cinchona trees to prevent Malaria.
Thus gene pool conservation is important for sustainable development.