WHAT IS THE GENE POOL? - BIOLOGY - 2025

The gene pool is a term used in population genetics to describe the set of alleles carried by all the individuals that are part of the population. It is also called a gene pool or “gene pool”.

In the same way, each specific gene has its own gene pool, made up of each of the alleles of that gene. In a population, each individual is considered unique from the point of view of their genetic makeup.

Source: By Smihael, from Wikimedia Commons

Understanding the concept of gene pool is key to evolutionary biology, as the term is embedded in the definition of evolution. Thus, a population is in equilibrium when the gene pool does not vary; In contrast, we say that the population is evolving if there is a change in the gene pool from one generation to the next.

We can take an allele and determine its frequency - the gene frequency - and we can also express it in percentage terms as a representation of the abundance of the allele in question, compared to the rest of the alleles that we find in the population.

Definition

The gene pool is defined as the entire set of genes in a population. In biology, the definition of population refers to a grouping of individuals of the same species that share a physical space and can potentially reproduce.

The term was first used in 1920 by the Russian-born geneticist Aleksandr Sergeevich. Thus, the famous and influential evolutionary biologist Theodosius Dobzhansky, brought the term to the United States and translated it as "gene pool".

Each gene can come in various forms or variants, and each is considered an allele.

For example, let's take as a hypothetical example a gene that codes for the fur of a certain mammal. This mammal can have a white or black fur. The gene that codes for the color white is considered an allele, also for the other characteristic.

Consequences in the variation of gene pools

Each population has a gene pool that characterizes it, some are rich in different genes, while others have poor variation in all of their genes.

Populations that have abundant variation in their gene pools may present favorable variations that allow an increase in their frequency in the population.

It is necessary to remember that the variation in a population is an indispensable condition so that the mechanisms that give rise to the evolution can act - call it natural selection or genetic drift.

On the other hand, reduced gene pools can have serious consequences on the fate of the population - in the most serious cases it promotes extinction. In certain populations of felines, for example, genetic variation is extremely poor and therefore they are said to be in danger of extinction.

The gene pool in genetics and evolutionary biology

From the point of view of population genetics, microevolution is defined as the "change in allele frequencies in a population".

In population studies, geneticists often focus on the set of genes in a population at a given time. The gene pool is considered as the receptacle from which the offspring obtain their genes.

Genes have a physical location, known as loci, and this may be made up of two or more alleles in the gene pool. At each location, an individual can be homozygous or heterozygous. In the first case, the two alleles are identical, while a heterozygote has two different alleles.

Gene Pool in Spotted Moths

The typical example in evolutionary biology is that of the speckled moth. In this lepidopteran there are two alleles that determine the color of the body. One of them determines the light color and the other the dark color.

As time passes, the frequencies of both alleles can change in the population. Human action has had a prominent effect on the evolution of color in moths.

In uncontaminated areas, the allele that determines the light color will increase in frequency, since it gives a fitness advantage to the individual who possesses it. For example, it can act as camouflage in the light bark of trees in the area.

In contrast, polluted areas often darken the bark of trees. In these regions, the relative frequency of the allele for the dark color will increase.

In both cases, we are observing change in the relative frequencies of the alleles. This variation in the gene pool is what we know as microevolution.

The origin of the human gene pool

Pääbo (2015) gives us a look at the varied gene pool of our species. The origin of how modern humans emerged has always been of special interest to paleontologists and evolutionary biologists. Next we will make a summary of the author's work:

Does all of our gene pool come from Africa?

The best known theory is the origin of man in Africa, and subsequent dispersion throughout the world. Thus, our ancestors competitively displaced the rest of the hominids that inhabited the planet, without exchanging genes with them.

In contrast, another point of view argues that gene exchange did exist between hominid populations, forming a kind of “regional continuity”.

Both theories formulate different origins of how all the variation in our gene pool originated, whether all the variation we found came from Africa or has deeper roots and origins.

Current evidence

The evidence found in the genome of Neanderthal man (Homo neanderthalensis) allows us to conclude that none of the views raised is totally correct. In fact, our gene pool is more complex than we expected.

While it is true that the human gene pool originated in Africa, approximately 1 to 3% of the genome originated outside of sub-Saharan Africa, and shows ancestry from Neardental man.

About 5% of our gene pool seems to come from a group located in Oceania: Denisovans, a distant relative of the Neanderthals, whose sequence comes from a bone found in southern Siberia.

Current evidence supports at least three gene "movements": one from the Neandertals to the ancestor of Asians, another from the Neandertals to Denisovans, and a final flow from Denisovans to an unknown group of hominids that split off from the lineage about a million years ago.

References

1. Campbell, NA (2001). Biology: Concepts and relationships. Pearson Education.
2. Dawkins, R. (2010). Evolution: The Greatest Show on Earth. Grupo Planeta Spain.
3. Freeman, S., & Herron, JC (2002). Evolutionary analysis. Prentice Hall.
4. Monge-Nájera, J. (2002). General biology. EUNED.
5. Pääbo, S. (2015). The diverse origins of the human gene pool. Nature Reviews Genetics, 16 (6), 313-314.