What is genetic evolution?

Sexual reproduction produces distinct population variations. Heredity determines the traits and qualities to be passed down to the progeny. Over time, this variation within-species is also affected by the process of human evolution. The study of how genetic variation leads to evolutionary changes is known as genetic evolution. If a trait helps an organism to survive and reproduce, it is more likely to be passed down the generations. It is rare that such traits result in a completely distinct set of traits in descendants than the ancestral population; this can result in the emergence of a new species.

Forces that drive genetic evolution

The modern synthesis theory of evolutionary changes describes human evolution as genetic variation within species that gives rise to the formation of new species. These microevolutionary changes in the population are caused by the combined action of evolutionary factors such as mutation, genetic drift, gene flow, and natural selection that evolve to noticeable macro changes in the population over time.

Mutation

DNA (Deoxy-ribonucleic acid) is the genomic material that determines a living organism's physiology, behavior, and appearance. Any alteration in an organism's DNA sequence results in the emergence of mutation, which is the most common cause of different genome traits in all living things. DNA replication can occur naturally, while mutation is produced as a result of DNA damage caused by environmental factors such as exposure to radiation and chemicals. The variation in the traits of the beta-globin gene family is another good example of mutation. Scientists analyzed many beta-globin genes from different species and determined that the gene developed over time from leghemoglobin in plants to hemoglobin and myoglobin in animals.

In an organism, mutation results in the production of a new DNA sequence that results in the formation of a new allele. In the course of reproduction, this new genome (allele) is passed on to the progeny. For instance, penicillin was discovered to be resistant to E. coli bacteria because of a genetic mutation that allowed the bacteria to hydrolyze penicillin by producing an enzyme known as penicillinase.

Genetic drift

Genetic drift is defined as a random fluctuation in a population's variability in the genome. It is a random occurrence that causes features to arise or vanish in a small population. It is a completely random process that usually takes one of two forms, the population bottleneck, and the founder effect. When a population is hunted to extinction or is wiped out due to natural disasters or habitat loss, the bottleneck effect occurs. As a result, there is a loss of population, which leads to the loss of alleles and genomic variety. When a portion of the population leaves the old population and relocates to a new site, this frequency-dependent process is known as the founder effect. This severely lowers the aging population's pool of genomes, resulting in a loss of genetic variation. Both the types of genetic drift untimely contribute to evolutionary changes in humans.

Gene flow

When a population migrates, genes from one group to the other are transferred. It can also happen without migration if some species travel to other areas and mate with the species of that area. Even if the migrated population returns, gene transfer occurs between the populations. The gene pool of the species is altered as a result of the gene transfer, resulting in evolutionary changes. Gene flow between species can also occur as a result of the crucial invasion when viruses transfer portions of DNA from one species to the other.

Natural selection

Mutation results in the survival of organisms in different environment and if favorable result in natural selection. Charles Darwin, the founder of modern theory of evolution, was the first to investigate this topic. He claimed that organisms that are better adapted to their environment have a better chance of surviving and passing on their genetic material. As a result, the species evolved and diversified over time. Giraffes, for example, have evolved long necks to allow them to eat tall vegetation that is difficult to reach for other animals. As a result, their chances of survival improved since they had easier access to food. Natural selection, which focuses on the survival of the fittest, has led to the evolution of millions of species on the planet.

Natural selection can also include non-genetic selection, such as phenotypic plasticity, or an organism's response to environmental changes through morphological, physiological, or behavioral traits. For instance, various generations of butterflies (such as Araschnia Levana) may acquire different color patterns on their wings, known as the spring and summer patterns, based on which season they emerge from the pupa. Phenotypic plasticity influences the ultimate result of diversity at the population level by influencing an organism's response to natural selection.

How do genetics support evolution?

Genetic diversity results in differences in an organism's DNA sequence or protein function, resulting in the production of distinct gene alleles. Different phenotypic features in an organism are caused by these alleles or genotypic differences. If these characteristics favor natural selection, they are more likely to be handed down to the next generation. As a result, gene diversity benefits the population because it increases the population's chances of survival and reproduction through natural selection. The SARS-CoV-2 virus (Severe acute respiratory syndrome coronavirus 2), which causes COVID-19 (CoronaVirus Disease 2019) in people and certain animals, is one of the clearest examples of how genetics aids evolution. The virus became more infectious as a result of genomic evolution in the form of the delta COVID-19 variation.

The application of Hardy-Weinberg law is one of the most effective methods used by scientists to discover how genetics supports evolutionary changes in organisms. In the absence of evolutionary forces such as mutation, natural selection, immigration, emigration, and so on, the law asserts that a population's genotypic frequencies within a species remain constant from generation to generation. However, it is known that the population is always changing, so the law cannot be applied to the population in the real world. However, it establishes a baseline against which scientists can compare the evolving populations to non-evolving populations.

Common Mistakes

Students frequently have trouble distinguishing between genetics, natural selection, and genetic evolution. Genetics is the study of a species' genome or genetic resources. Natural selection is the phenomenon of the fittest species being selected on the basis of the features passed down from generation to generation in response to well-adapted changes. Genetic evolution, on the other hand, is the result of genetics and natural selection, as well as other elements.

Context and Applications

This subject is important in professional exams for both undergraduate and graduate levels, particularly in biology, zoology, botany, and animal physiology.

Practice Problems

Question 1) Which of the following forces also drive genetic evolution along with mutation, genetic drift and gene flow?

1. Natural selection
2. DNA
3. Environmental factors
4. Migration

Answer: Option a.

Explanation: Natural selection favors the survival of the species that are better adapted to the environmental changes, these favorable genetic traits are then passed down from one generation to the other.

Question 2) Which of the following enzyme is produced by Escherichia coli to hydrolyze penicillin?

1. Penicillin
2. Penicillium
3. Penicillinase
4. Mutation

Answer- Option c.

Explanation- Escherichia coli bacteria produces a penicillin hydrolyzing enzyme called penicillinase by undergoing a point mutation in its DNA sequence.

Question 3) State the most effective methods used by scientists to discover how genetics supports evolutionary changes in organisms.

1. Hardy-Weinberg law
2. Hardy law
3. Weinberg law
4. Newton's law

Answer- Option a

Explanation- Hardy-Weinberg law establishes a baseline against which scientists can compare the evolving populations to non-evolving populations.

Question 4) What is the name given to an organism's response to environmental changes via morphological, physiological, or behavioral traits?

1. Phenotypic plasticity
2. Genotypic plasticity
3. Phenotype
4. Genotype

Answer- Option a

Explanation- Phenotypic plasticity is a subset of the natural selection process that results in phenotypic diversity at the population level based on their responses to the changes in the environment.

Question 5) Which genetic factor is responsible for the formation of long necks in giraffes?

1. Genetic drift
2. Gene flow
3. Natural selection
4. Mutation

Answer- Option c

Explanation- Natural selection is responsible for adaptations of long necks among giraffes as they allow them to eat tall vegetation that is difficult to reach for other animals.

Related concepts

• Evolution
• Population genetics
• Evolutionary biology