Question

Which of the following evolutionary mechanisms acts to slow down or prevent the evolution of reproductive isolation? a. natural selection b. gene flow c. mutation d. genetic drift

Short answer

Gene flow

Step-by-step solution

Understand the Evolutionary Mechanisms

Examine each of the given evolutionary mechanisms: natural selection, gene flow, mutation, and genetic drift. Understand how each mechanism influences genetic variation and reproductive isolation.

Evaluate Natural Selection

Natural selection tends to favor individuals with advantageous traits, leading to adaptation. It can increase reproductive isolation by selecting for traits that are beneficial in a particular environment, potentially causing populations to diverge.

Assess Gene Flow

Gene flow involves the transfer of genetic material between populations. This mixing of genes can homogenize differences between populations, thus acting to prevent the evolution of reproductive isolation by reducing genetic divergence.

Analyze Mutation

Mutations introduce new genetic variations into a population. While mutation itself does not directly prevent reproductive isolation, it contributes to genetic diversity, which can lead to evolutionary changes.

Consider Genetic Drift

Genetic drift is the random change in allele frequencies in a population. Especially in small populations, genetic drift can lead to random divergence and potentially increase reproductive isolation.

Identify the Correct Mechanism

Based on the steps above, gene flow is the mechanism that slows down or prevents the evolution of reproductive isolation by introducing genetic material between populations, decreasing divergence.

Key concepts

natural selection

Natural selection is a fundamental mechanism of evolution. It works on the principle that individuals with traits better suited to their environment are more likely to survive and reproduce.
Over time, these advantageous traits become more common in the population.
This process can lead to adaptation, where species evolve traits that make them better suited to their environment.
It's essential to note that natural selection can contribute to reproductive isolation when different populations adapt to different environments.

• It increases reproductive isolation as beneficial traits become prevalent in specific environments.
• Populations may diverge, creating new species.

Natural selection plays a vital role in the diversity of life as we see it today.

gene flow

Gene flow involves the movement of genes or alleles between populations.
This occurs when individuals from one population breed with individuals from another, introducing new genetic material.
Gene flow tends to decrease genetic differences between populations and can slow or prevent reproductive isolation.

• By mixing genetic material, it keeps populations similar.
• It prevents divergence, making it a counteracting force against speciation.

In essence, gene flow homogenizes genetic differences, maintaining genetic unity across populations.

reproductive isolation

Reproductive isolation refers to mechanisms that prevent different species from interbreeding.
These barriers can be prezygotic or postzygotic.
Prezygotic barriers occur before fertilization, such as differences in mating rituals or physical incompatibility.

• Postzygotic barriers occur after fertilization, leading to reduced viability or sterility of hybrids.
• Reproductive isolation is crucial for speciation, as it prevents gene pools from mixing.

Understanding reproductive isolation helps explain how new species arise and maintain their distinct genetic identities.

genetic drift

Genetic drift refers to random changes in allele frequencies within a population.
Unlike natural selection, genetic drift is random and has a more significant effect in small populations.
It can lead to the fixation or loss of alleles over time.

• In small populations, genetic drift can cause significant changes quickly.
• It can contribute to reproductive isolation by causing random divergence.

Although genetic drift is a less predictable force, it is an essential part of the evolutionary process, contributing to the diversity of life.

mutation

Mutations are changes in the DNA sequence of an organism.
They can introduce new genetic variations into a population.
While most mutations are neutral or harmful, some can provide advantageous traits.

• Mutations are the raw material for evolution, creating genetic diversity.
• They can lead to evolutionary changes over time.

Although mutation alone does not directly prevent reproductive isolation, it is a crucial driver of genetic variation, enabling other evolutionary mechanisms to act.