Genetic diversity refers to the variability within the genetic pool of the organisms. It’s the sum of all genetic characteristics in the species’ makeup. It includes not only the wide range of species but also the diversity within one species.
Each species consisted of individuals that possess their unique genetic composition. Genetic diversity has different populations with each population having different genetic makeup. Genetic diversity within a species helps to ensure that species’ long-term survival.
Each of the individual species has genes that are the source of its unique characteristics and features. For instance, genetic diversity is the reason why human beings look different from one another even though they’re from the same family, culture, or race.
There are several hypotheses and theories about genetic diversity in the population genetics field. The theory of evolution deems diversity as the result of the cumulative process of neutral exchange. The higher rate of neutral exchange within a population can contribute to a more heterogeneous genetic diversity.
Why is genetic diversity important?
Genetic diversity acts as a way for populations to adapt and respond to changing conditions and environments. All species on Earth thrive through survival and adaptation.
Some individuals within a population may have higher tolerance toward damage and pollutants in the environment, while some may suffer and die. The different levels of tolerance are due to the different types of genes within the individual.
The huge variety of gene sets allow different individuals to thrive and survive in the same environmental conditions. The greater the variety, the better chances a species has to survive even though many of its individuals may not.
With more variations in the genetic pool, individuals are more likely to possess different types of alleles that are suitable for the environment around them. Through this, the species is more likely to survive and in turn, produce offspring with similar alleles.
The ability of a population to respond, react, and adapt to the changing environment depends on the presence of the necessary and required genetic diversity. Genetic diversity ensures the longevity of a species on Earth.
It allows their species to continue for many generations because they possess higher tolerance to the stress from the environment.
How does crossing over contribute to genetic diversity?
Crossing over is the swapping of chromosome segments. It creates new combinations in the gene makeup of the gametes, the reproductive cells of organisms, which are not present in either parent. This process is also known as recombination.
An individual in each species possesses body cells made up of pairs of each chromosome. In each pair, one part comes from the mother, and another part is from the father. The formation of each gene is called alleles. These alleles may be different in each pair of chromosomes.
By crossing over or recombining these chromosome segments, scientists can contribute to genetic diversity. Since this process alters the gene makeup, it creates more variations within the gene pool.
Crossing over aims to maintain genetic diversity within a population by allowing nearly infinite gene combinations and recombination possibilities. This helps to maintain and encourage a population’s genetic diversity.
The higher the genetic diversity within a species is, the better chance it has for long-term survival. If a population reproduce among its members only, negative traits such as disorders or inherited diseases will become widespread within that population, causing it to go extinct sooner or later.
Crossing over doesn’t just ensure the variability of individuals within a species. It contributes to the evolutionary importance of said species. It allows a species to adapt better to changing environments and it also helps to allow small populations to grow and thrive.
A larger population may have a better chance of survival since they have a higher rate of genetic diversity. Small populations may become extinct because they experience a higher loss of diversity. Crossing over helps to enrich the diversity within small populations so they too have a chance at long-term survival.
Furthermore, genetic crossing over also contributes to agriculture genetic diversity.
As human relies on crops for food, crossing over can help farmers grow better and healthier crops. Agriculture selective breeding allows farmers to pass on valuable traits of the crops while removing the unwanted ones.
The new crossed over crops yield better produces and thus allowing humans and animals to consume better food that contributes to their overall health. Crops are more susceptible to diseases and bacterial growth if there is genetic diversity in agriculture.
Not just in crops, crossing over in genetic diversity in livestock is also important. Many farmers rely on animal husbandry for livelihood. It’s the care and management of farm animals where genetic diversity plays an important role and is highly advantageous in agriculture.
Crossovers can shuffle the alleles combination so each pair of chromosomes will have both good alleles. When the good pair competes with a pair that has bad alleles, the good pair will win over in the genetic diversity in future generations.
Since the environment is always changing, both naturally and due to human activities, species constantly need to thrive to survive. By crossing over genetics, the good alleles in the chromosomes allow the species to adapt better and be healthier. Even though some of the offspring will die, genetic crossovers increase the chance of a species’ survival.
How does having a diverse gene pool help a species survive?
As mentioned, when a species is extinct, it’s almost impossible for it to come back. While there are scientific processes that try to make this possible, extinction is the ultimate end for many species.
Since biodiversity is crucial for the survival of all species on Earth, having a diverse gene pool can help a species survive. The offspring of that species has better chances of living longer life and fight off inherited diseases.
Species with a limited range of phenotypes where all individuals of the species are genetically similar to one another have a poorer chance of dealing with changes in the environment. Conversely, a species with a wide range of phenotypes can adapt better and thus increase their survival rate.
This is why the survival and longevity of their progeny can be compromised if a population chooses to reproduce among its own members only. There is no diversity to help the good genes survive. Genetic diversity is not just about the species’ ability to adapt to changing environments. It’s also about the quality of life it produces.
Even in a situation where a species has been living for a long time and seems to adapt well to the environment, it doesn’t mean the environment will remain stable. Any sudden changes can still happen, and these changes greatly affect a species’ ability to survive.
A population will modify itself to adapt to these environmental changes. If there’s limited genetic diversity within that population, it will restrict its ability to adapt or evolve. Sooner or later this failure will lead to the extinction of that population and by extension, its species.
This Genetic Diversity article is part of our Biodiversity Series.