Microevolution - Key Drivers
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What are the three main drivers of population-level evolution?

  • Natural selection, artificial selection, and genetic drift
  • Natural selection, genetic drift, and gene flow (correct)
  • Genetic drift, gene flow, and selective breeding
  • Gene flow, natural selection, and adaptation

What is the term for the process by which a population's genetic makeup changes due to random chance, particularly affecting small populations?

  • Adaptation
  • Genetic drift (correct)
  • Gene flow
  • Natural selection

Which of the following describes the effect of gene flow on genetic diversity?

  • Gene flow always increases genetic diversity by introducing new alleles.
  • Gene flow has no effect on genetic diversity, as alleles are simply transferred between populations.
  • Gene flow always decreases genetic diversity by homogenizing populations.
  • Gene flow can either increase or decrease genetic diversity depending on the specific alleles involved. (correct)

What is a bottleneck in the context of population genetics?

<p>A sudden decrease in population size due to a catastrophic event (D)</p> Signup and view all the answers

What is the primary reason why genetic drift has a more pronounced effect on smaller populations?

<p>Smaller populations have less genetic variation, making random changes in allele frequencies more significant. (D)</p> Signup and view all the answers

What is the founder effect?

<p>The phenomenon where a small group of individuals colonize a new area and their genetic makeup becomes the foundation for the new population (A)</p> Signup and view all the answers

Which of the following is NOT a type of natural selection?

<p>Artificial selection (B)</p> Signup and view all the answers

Which of these is an example of human-induced genetic drift?

<p>The changes in allele frequencies in a population of fish due to overfishing. (A)</p> Signup and view all the answers

Which of the following statements is TRUE about the effects of genetic drift?

<p>Genetic drift can lead to the loss of beneficial alleles and the fixation of harmful alleles. (D)</p> Signup and view all the answers

What is the term for the ability of an organism to change its phenotype in response to environmental changes?

<p>Phenotypic plasticity (B)</p> Signup and view all the answers

What is the primary mechanism by which gene flow occurs?

<p>The transfer of alleles between populations through the movement of individuals or gametes. (D)</p> Signup and view all the answers

How does genetic drift differ from natural selection?

<p>Genetic drift is a random process, while natural selection is based on fitness differences (C)</p> Signup and view all the answers

Which of the following human activities can contribute to genetic drift?

<p>Overhunting or overfishing of certain species (A)</p> Signup and view all the answers

What is the main idea behind the concept of genetic drift?

<p>Evolutionary changes driven by random fluctuations in allele frequencies within a population. (A)</p> Signup and view all the answers

What is a key difference between genetic drift and natural selection?

<p>Genetic drift is random, while natural selection is driven by environmental pressures. (D)</p> Signup and view all the answers

Which of the following is an example of the founder effect?

<p>A small group of insects is accidentally transported to a new island. (B)</p> Signup and view all the answers

What is a potential consequence of genetic drift?

<p>Reduced fitness of a population. (A)</p> Signup and view all the answers

How does size-selective harvesting impact populations?

<p>It can lead to a decrease in the average size of individuals in the population. (D)</p> Signup and view all the answers

What is a potential consequence of trophy hunting?

<p>Favoring the survival of individuals with less desirable (for hunting) traits. (C)</p> Signup and view all the answers

How can genetic drift affect the long-term survival of a population?

<p>It can lead to an increase in the frequency of harmful alleles. (D)</p> Signup and view all the answers

In the example of the Tiburon Island desert bighorn sheep population, what is a likely factor that contributed to the increase in population size?

<p>A combination of factors including genetic drift and favorable environmental conditions. (A)</p> Signup and view all the answers

Flashcards

Genetic Drift

Random changes in allele frequencies in a population over time due to chance events.

Founder Effect

A phenomenon where a small group becomes isolated and establishes a new population with different allele frequencies.

Isolation

When a small group of individuals becomes separated from the larger parent population.

Desert Bighorn Sheep Example

A study showing how a small founder population increased significantly in size over time.

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Human-Induced Genetic Drift

Changes in allele frequencies caused by human activities, such as selective harvesting.

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Selective Harvesting

The practice of harvesting individuals based on specific traits, often size or attributes, affecting population genetics.

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Trophy Hunting

A hunting practice where individuals harvest animals for sport, often targeting individuals with desirable traits.

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Size-selective Fishing Example

Fishing methods that only catch larger individuals, impacting the overall genetic makeup of fish populations.

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Microevolution

Small-scale evolutionary changes within a population over time.

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Natural selection

Process where organisms better adapted to their environment tend to survive and produce more offspring.

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Bottleneck effect

Sharp reduction in population size due to environmental events or human activities, leading to decreased genetic diversity.

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Phenotypic plasticity

The ability of an organism to change its phenotype in response to environmental changes.

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Types of Natural Selection

Includes directional, disruptive, and stabilizing selection, mechanisms that drive evolution.

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Costs and Benefits of Gene flow

Movement of genes between populations can introduce new alleles but also can disrupt local adaptations.

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Effects of Genetic Drift

Can change allele frequencies randomly, reducing variation, and fixing harmful alleles.

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Gene Flow

Transfer of alleles between populations through movement of individuals or gametes.

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Beneficial Gene Flow

Increases genetic diversity by introducing new alleles into a population.

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Harmful Gene Flow

Potentially decreases local adaptation by blending different populations.

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Study Notes

Microevolution - Key Drivers

  • Natural selection: Adaptations change allele frequencies
  • Genetic drift: Chance events alter allele frequencies
  • Gene flow: Transfer of alleles between populations

Microevolution - Natural Selection

  • Driving force of evolution
  • Individuals with traits better suited to their environment have higher survival and reproductive rates.
  • Over generations, beneficial traits become more common.

Microevolution - Genetic Drift

  • Random changes in allele frequencies
  • Significant in small populations.
  • Chance events (e.g., natural disasters, disease outbreaks, or founder effect) can drastically alter allele frequencies.
  • Bottlenecks: drastic reduction in population size leads to loss of genetic variation.
  • Founder effect: establishing a new population from a small group can lead to reduced genetic diversity compared to the original population.
  • Examples: Northern elephant seals, California condors

Microevolution - Gene Flow

  • Movement of alleles between populations.
  • Individuals migrating between populations introduce new alleles or change the proportion of existing alleles.
  • Increases genetic diversity in recipient populations.
  • Examples: Wind pollination, animal migration, dispersal of seeds by animals
  • Importance in conservation biology

Human-Induced Selective Harvesting

  • Selective harvesting (e.g., trophy hunting, fisheries) can impact populations.
  • Often, individuals with specific traits (based on size or other characteristics) are targeted.
  • Can lead to significant genetic consequences altering the genetic diversity in the population.
  • Examples: Trophy hunting of bighorn sheep, fisheries targeting larger fish

Genetic Drift - Consequences

  • Significant in small populations
  • Random changes in allele frequencies
  • Loss of genetic variation.
  • Harmful alleles can become fixed, while beneficial alleles can be lost.
  • Examples: Greater prairie chickens (Illinois population), which lost considerable genetic variation due to a drastic population decline from the 1800s to the 1990s.

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Description

This quiz explores the key drivers of microevolution, including natural selection, genetic drift, and gene flow. Understand how these mechanisms influence allele frequencies and contribute to evolutionary changes in populations. Test your knowledge on these fundamental concepts of evolutionary biology.

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