Question

Which of the following is an assumption of the Hardy-Weinberg model? A. Mating between populations occurs at a set rate. B. Mutation occurs at a set frequency. C. Positive selection for certain genotypes occurs but does not eliminate any genes. D. The population being studied is large and stable.

Short answer

Option D

Step-by-step solution

Understand the Hardy-Weinberg Model

The Hardy-Weinberg model is a principle in genetics that describes the genetic equilibrium within a large, randomly mating population where allele and genotype frequencies remain constant from generation to generation in the absence of other evolutionary influences.

Identify the Assumptions

The Hardy-Weinberg model makes several assumptions to hold true: no mutation, random mating, no gene flow, infinite population size (which can be approximated with a large population), and no selection.

Analyze the Given Options

Option A mentions 'Mating between populations occurs at a set rate', which is incorrect as the model assumes no gene flow between populations.Option B states 'Mutation occurs at a set frequency', which is incorrect because the model assumes no mutations.Option C indicates 'Positive selection for certain genotypes occurs but does not eliminate any genes', which is incorrect as the model assumes no selection.Option D mentions 'The population being studied is large and stable', which aligns with the infinite population size assumption of the model.

Choose the Correct Option

After analyzing all given options, Option D ('The population being studied is large and stable') is the only one that correctly represents an assumption of the Hardy-Weinberg model.

Key concepts

genetic equilibrium

Genetic equilibrium is a key concept in population genetics. It refers to the condition where the allele frequencies in a population remain constant over generations. This is described well by the Hardy-Weinberg model.

For genetic equilibrium to occur, the population must meet specific criteria. The Hardy-Weinberg model requires the absence of evolutionary influences such as mutation, selection, gene flow, genetic drift, and non-random mating.

Maintaining genetic equilibrium allows scientists to predict how genetic variation is distributed within a population in an ideal state. Any deviation from this equilibrium suggests the influence of one or more evolutionary forces.

Understanding genetic equilibrium helps researchers determine whether a population is evolving and, if so, what factors are causing the change in genetic diversity.

random mating

Random mating is another critical assumption of the Hardy-Weinberg model. It means that all individuals in the population are equally likely to mate with each other, without preference for any specific genotype or phenotype.

In a randomly mating population, the alleles have an equal chance of pairing up in the next generation, ensuring that all genotype frequencies are in proportion to allele frequencies. This is crucial to maintaining genetic equilibrium.

The importance of random mating lies in its role in preventing deviations from expected genotype frequencies. If non-random mating occurs, certain alleles can become overrepresented or underrepresented in the gene pool, leading to evolutionary changes.

Thus, random mating helps maintain the genetic structure of a population by ensuring that allele frequencies remain stable across generations.

population genetics

Population genetics is the study of how genetic variation is distributed and changes over time in populations.

It focuses on the genetic makeup of populations and how it evolves under the influence of various evolutionary forces. Population genetics combines Mendelian genetics with Darwinian evolution and uses mathematical models to understand genetic structure.

The Hardy-Weinberg model is a cornerstone of population genetics. By setting a theoretical framework for genetic equilibrium, it allows researchers to study deviations caused by evolutionary influences such as mutation, selection, genetic drift, and gene flow.

This field is critical for understanding biological diversity, adaptation, and the evolutionary history of populations. It has practical applications in conservation biology, medicine, and agriculture, helping us manage and preserve genetic resources.

evolutionary influences

Evolutionary influences are forces that affect allele frequencies in populations, driving evolutionary change. These include:

• Mutation: Random changes in DNA sequences introducing new genetic variants.
• Selection: Differential survival and reproduction of individuals based on their genetic traits.
• Genetic Drift: Random fluctuations in allele frequencies due to chance events, particularly in small populations.
• Gene Flow: Movement of genes between populations through migration.
• Non-Random Mating: Preference for mating with specific individuals, altering allele frequencies.

Each of these factors can disrupt genetic equilibrium predicted by the Hardy-Weinberg model. Understanding these forces helps illustrate why natural populations rarely meet all the model's assumptions. They highlight the complexity and dynamic nature of genetic variation in real-world populations.

By studying evolutionary influences, scientists can trace the pathways of genetic change and understand the mechanisms driving evolution and adaptation.