Question

Population geneticists are interested in the genetic variation in populations. The most common type of genetic change that causes polymorphism in a population is a a deletion of a gene sequence. b. a duplication of a region of a gene. c. a rearrangement of a gene sequence. d. a single-nucleotide substitution. e. an inversion of a segment of a chromosome,

Short answer

The most common type of genetic change that causes polymorphism in a population is a single-nucleotide substitution

Step-by-step solution

Understanding the Types of Genetic Changes

Firstly, the various types of genetic changes that can occur should be familiarized. These include deletions, duplications, rearrangements, single-nucleotide substitutions, and inversions within the DNA structure.

Identify the Most Common Genetic Change

After understanding the diverse types of genetic changes, it's necessary to recognize which is the most common one causing polymorphism in populations. By referencing a range of scientific research resources, it is found that a single-nucleotide substitution is often the most common cause.

Select the Correct Answer

On basis of the conclusion made in the second step, the correct answer amongst the options is identified. In this case, it is option 'd - a single-nucleotide substitution.'

Key concepts

Genetic Variation

Genetic variation is the foundation of evolution and natural selection. It refers to the differences in the genetic makeup among individuals within a population. These differences arise due to changes or mutations in the DNA sequence.
This variation is crucial because it provides the material for natural selection to act upon. Without genetic variation, all individuals would be genetically identical, eliminating the potential for adaptation to environmental changes.

• Genetic variation contributes to the diversity of traits that can be seen in features such as height, skin color, and resistance to diseases.
• It is typically caused by mutations, gene flow, and sexual reproduction, which shuffles alleles in offspring.

Understanding genetic variation is essential for fields like conservation biology, agriculture, and medicine, as it helps predict potential future changes and challenges within populations.

Polymorphism

Polymorphism in a population occurs when two or more clearly different phenotypes exist within the same species. This term is often used to describe genetic differences among individuals.
Polymorphic traits are usually the result of genetic variation and are commonly studied by population geneticists to understand evolution and disease resistance.

• An example of polymorphism in humans is the ABO blood group system.
• It serves as a practical way of evaluating how natural selection and genetic drift affect populations.

Polymorphism is significant as it reveals the adaptability of populations and the direction of evolutionary pressures.

Single-Nucleotide Substitution

A single-nucleotide substitution, also known as a point mutation, is a change at a single position in the DNA sequence. It is one of the most common types of genetic mutations.
This tiny change can have various outcomes. Sometimes it doesn't affect the organism at all, while other times, it can lead to significant changes in phenotype, such as disease susceptibility or resistance.

• These substitutions can occur through transitions (a purine replaces a purine or a pyrimidine replaces a pyrimidine) or transversions (a purine replaces a pyrimidine, or vice versa).
• Single-nucleotide substitutions can be used as markers to study genetic variation and understand evolutionary processes.

Despite being small changes, their effects can be profound, influencing everything from protein functions to entire evolutionary pathways.

Genetic Changes

Genetic changes refer to alterations in the DNA sequence that can affect an organism's genome. These include a variety of changes such as deletions, duplications, rearrangements, inversions, and single-nucleotide substitutions.
Such changes can occur naturally and are a source of genetic diversity within populations. They can lead to variations in traits that might provide survival advantages under certain conditions.

• While some genetic changes can be beneficial, others might result in disorders or diseases if they disrupt important functional sequences.
• Genetic changes play a crucial role in adaptation and speciation, ultimately driving evolutionary processes.

Understanding these changes helps scientists in fields such as genetics, biology, and medicine to unravel complexities in genetics and develop strategies to address various genetic disorders.