Biology 1120: Evolution of Populations Quiz
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Questions and Answers

What is the concept that describes the genetic makeup stability in a population under specific conditions?

  • Hardy-Weinberg principle (correct)
  • Mendelian inheritance
  • Genetic drift
  • Natural selection

Which of the following factors is NOT one of the five conditions required for genetic equilibrium?

  • Natural selection (correct)
  • No mutations
  • Large population size
  • Random mating

Which statement accurately conveys the relationship between phenotypic variation and genetic variation?

  • Phenotypic variation often reflects genetic variation. (correct)
  • Phenotypic variation has no relation to genetic variation.
  • All phenotypic variation arises from environmental factors.
  • Genetic variation only shows in individuals not in populations.

What role do mutations play in a population's genetic variation?

<p>They contribute to genetic variation by altering gene sequences. (A)</p> Signup and view all the answers

The understanding of diversity in organisms includes studying their interactions with what?

<p>Each other and the environment (A)</p> Signup and view all the answers

What results from a genetic bottleneck in a population?

<p>A decrease in allele frequencies compared to previous generations (D)</p> Signup and view all the answers

What is the founder effect?

<p>The result of a few individuals starting a new population (A)</p> Signup and view all the answers

How does gene flow affect genetic variation within a population?

<p>It generally increases variation within a recipient population (D)</p> Signup and view all the answers

What role does natural selection play in adaptive evolutionary change?

<p>It conserves individuals with beneficial traits (A)</p> Signup and view all the answers

What did researchers discover about the genetic diversity of the Florida Panthers?

<p>They have approximately one-third the genetic diversity of their ancestors (B)</p> Signup and view all the answers

What type of selection occurs when extreme phenotypes are favored and result in a decrease of intermediate phenotypes?

<p>Disruptive selection (C)</p> Signup and view all the answers

Which process maintains stable frequencies of multiple phenotypic forms in a population?

<p>Heterozygote advantage (C)</p> Signup and view all the answers

What does the Hardy-Weinberg principle state about the genotypes in a population at genetic equilibrium?

<p>They occur in the frequency of $p^2 + 2pq + q^2 = 1$. (A)</p> Signup and view all the answers

In a scenario where a population of finches has individuals with either long beaks or short beaks thriving, while those with medium beaks do not, what effect is being observed?

<p>Disruptive selection (D)</p> Signup and view all the answers

What is the expected outcome of stabilizing selection on a population's characteristics?

<p>Reduction in phenotypic variation (B)</p> Signup and view all the answers

Which of the following represents the frequency of the recessive genotype (aa) in a population?

<p>$q^2$ (B)</p> Signup and view all the answers

Under which condition does genetic equilibrium exist according to the Hardy-Weinberg principle?

<p>Random mating (A)</p> Signup and view all the answers

When a small group of individuals becomes isolated from a larger population and establishes a new population with reduced genetic diversity, this phenomenon is referred to as what?

<p>Founder effect (C)</p> Signup and view all the answers

What happens if one of the Hardy-Weinberg conditions is not met?

<p>Microevolution occurs. (B)</p> Signup and view all the answers

If the frequencies of blue and green fish in a population change because the more common color is selected against, what type of selection is at play?

<p>Frequency-dependent selection (D)</p> Signup and view all the answers

Which statement correctly describes heterozygote advantage in relation to malaria resistance?

<p>Heterozygotes offer greater resistance to malaria (B)</p> Signup and view all the answers

In a population, if the frequency of the dominant allele (A) is 0.8, what is the frequency of the recessive allele (a)?

<p>0.2 (B)</p> Signup and view all the answers

Which of the following is NOT one of the five processes of microevolution?

<p>Phenotypic variation (C)</p> Signup and view all the answers

Given allele frequencies of p=0.3 and q=0.7 after a tsunami event, what microevolutionary process likely occurred?

<p>Genetic drift (C)</p> Signup and view all the answers

What effect does genetic drift have on small populations?

<p>Decreases genetic variation within the population. (D)</p> Signup and view all the answers

In the context of allele frequency, what does the equation $p + q = 1$ signify?

<p>The combined frequency of dominant and recessive alleles. (B)</p> Signup and view all the answers

What does a gene pool represent in a population?

<p>All the alleles for all the loci present in a population (C)</p> Signup and view all the answers

Which term describes the physical or chemical expression of an organism's genes?

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

If a population has a genotype frequency of 0.49 for homozygous dominant (AA), 0.42 for heterozygous (Aa), and 0.09 for homozygous recessive (aa), what does the sum of these frequencies equal?

<p>1.00 (A)</p> Signup and view all the answers

How is allele frequency defined within a population?

<p>The proportion of a specific allele in a population (A)</p> Signup and view all the answers

What does genetic equilibrium indicate about a population?

<p>There is no net change in allele or genotype frequencies over time (B)</p> Signup and view all the answers

In a population of 1000 individuals carrying 2000 alleles, what is the allele frequency of allele 'A' if there are 1400 instances of allele 'A'?

<p>0.7 (A)</p> Signup and view all the answers

What would indicate that evolution is occurring in a population?

<p>Change in allele frequencies over generations (C)</p> Signup and view all the answers

Which of the following best describes genotype frequency?

<p>The proportion of a specific genotype in a population (A)</p> Signup and view all the answers

Flashcards

Population Genetics

The study of genetic variation within populations and how it changes over time.

Hardy-Weinberg Principle

Describes the conditions under which allele and genotype frequencies in a population will remain constant from generation to generation.

Genetic Equilibrium

A state where allele and genotype frequencies in a population remain constant over time.

Genetic Variation

Differences in the genes or DNA sequences among individuals in a population.

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Evolutionary Forces

Processes that can alter allele frequencies in a population, including mutation, natural selection, genetic drift, and gene flow.

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Genetic Bottleneck

A sharp decrease in population size due to factors like disease or environmental change. This event alters the allele frequencies of the population, potentially leading to loss of genetic diversity.

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Founder Effect

Genetic drift that happens when a small group of individuals starts a new population. The genes of the founders become the founding genes for the population, frequently resulting in different allele frequencies than the original population.

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Gene Flow

The movement of breeding individuals (and their alleles) between populations, increasing genetic variation in the recipient population.

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Adaptive Evolutionary Change

Natural selection changing a population over time by favoring individuals with traits helpful in a particular environment. These helpful traits are passed on to later generations.

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Genetic Drift

Random changes in allele frequencies in a population, especially pronounced in smaller populations. Genetic drift results from chance events. It can lead to the loss or fixation of alleles.

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Genotype Frequency

The proportion of a specific genotype in a population, expressed as a decimal fraction.

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Phenotype Frequency

The proportion of a particular observable trait (phenotype) in a population.

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Allele Frequency

The proportion of a specific allele (version of a gene) in a population.

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Hardy-Weinberg Equilibrium

The condition where allele and genotype frequencies in a population remain constant from generation to generation without outside influences.

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Genotype

The combination of alleles an individual has for a particular gene (or genes).

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Phenotype

The physical or chemical expression of an organism’s genes.

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Evolution of Populations

Describes how populations change over time in terms of genotype, phenotype, and allele frequencies.

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Natural Selection

The process where organisms with traits better suited to their environment are more likely to survive and reproduce, passing those traits to their offspring.

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Stabilizing Selection

Natural selection that favors average individuals in a population, reducing variation.

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Directional Selection

Natural selection that favors one extreme of a trait, causing the population to shift towards that extreme.

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Disruptive Selection

Natural selection that favors both extremes of a trait, reducing the frequency of the average.

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Balancing Selection

Natural selection that maintains stable frequencies of two or more phenotypes in a population.

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Heterozygote Advantage

A situation where heterozygotes (individuals with different alleles) have a fitness advantage over homozygotes.

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Microevolution

Evolutionary change within a species or population.

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Conditions of genetic Equilibrium

Random mating, no net mutations, large population size, no migration, and no natural selection. For Hardy-Weinberg to be present

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p2

Frequency of the homozygous dominant genotype (AA) in a population.

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2pq

Frequency of the heterozygous genotype (Aa) in a population.

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q2

Frequency of the homozygous recessive genotype (aa) in a population

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Study Notes

Biology 1120 - Professor Feely

  • Course name: Biology 1120
  • Instructor: Professor Feely
  • Office Hours: Holt Hall 217, Tuesdays 2-3:30 pm and Thursdays 1-2 pm. Contact for other times.

Course Information

  • Syllabus required
  • Review 21.2 due Thursday
  • Pearson login due Thursday
  • Optional EC by 28th

Course Objectives

  • Demonstrate knowledge of different levels of biological organization and apply it to differentiate between various taxonomic groups.
  • Demonstrate knowledge of evolution and apply it to various taxonomic groups.
  • Demonstrate knowledge of ecology at different levels of biological organization.

21.2: Evolution of Populations

  • Focuses on population genetics.
  • Covers the Hardy-Weinberg principle and conditions for equilibrium.
  • Explains how evolutionary forces alter allele frequencies.
  • Discusses the nature and extent of genetic variation in a population.

Learning Outcomes

  • Population genetics reviewed
  • Hardy-Weinberg principle defined
  • Five conditions for genetic equilibrium explained.
  • How key evolutionary forces alter allele frequencies explained.
  • Nature/extent of genetic variation detailed

Population Genetics

  • The study of genetic variation within a population

  • Estimates the amount of observed variation within.

  • Important for understanding evolutionary processes.

  • Gene pool includes alleles of all loci.

  • Diploid organisms have two alleles at each locus with Homozygous, Heterozygous.

  • Each individual has a unique subset of alleles.

Gene Pool Analysis

  • Evolution described in terms of genotype, phenotype and allele frequencies.
  • Genotype definition: combination of alleles in an individual.
  • Genotype frequency: proportion of a particular genotype in a population (expressed as a decimal).
  • Phenotype definition: physical or chemical expression of an organism's genes.
  • Phenotype frequency: proportion of a particular phenotype in a population.
  • Allele frequency: proportion of a specific allele (A or a) in a population.

The Hardy-Weinberg Equilibrium

  • Allele and genotype frequencies in a population do not change over generations unless impacted by outside forces.
  • Genetic equilibrium: no net change in allele or genotype frequencies over time.
  • Evolution is demonstrated by change in allele frequencies across generations.

Hardy-Weinberg Principle (Cont'd)

  • Genotypes at equilibrium occur in specific frequencies (p² + 2pq + q²= 1).  - p² : frequency of AA
  • 2pq : frequency of Aa
  • q² : frequency of aa

Conditions of Genetic Equilibrium

  • Five conditions are met for equilibrium: random mating, no net mutations, large population size, no migration, and no natural selection. 
  • Failure of any of these leads to microevolution.

Microevolution

  • Changes in allele or genotype frequencies within a population over generations.
  • Five microevolutionary processes are detailed, opposite of genetic equilibrium.
  • Nonrandom mating, Mutation, Genetic drift, Gene flow and Natural selection.
  • Focus on the effects for example, genetic drift, genetic bottlenecks and natural selection (examples given).

Natural Selection Acts on Phenotype

  • Natural Selection leads to changes as populations adapt to different environments and ways of life.
  • Preserves and eliminates phenotypes (and their genes) that are advantageous or unfavorable.
  • Individuals that survive and reproduce have a selective advantage.
  • Different types of natural selection are detailed, including directional, stabilizing and disruptive.

Practice Questions

  • In corn, purple kernels are dominant, yellow. Question about phenotypic frequency or allele frequencies from given data.
  • Founder effect example: example question given about a flock of finches colonising a new island.
  • Selection in Galapagos finches: example question given about drought in Galapagos led to finches with long or short beaks.
  • Tsunami and rose allele frequencies: detail of a tsunami impact on a population of rose plants.

Balancing Selection

  • Natural selection maintains stable frequencies of two or more phenotypic forms.  
  • Heterozygote advantage example: sickle cell allele and malaria resistance detailed in regions.

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Related Documents

Lecture 01 - Evolutionary Change in Populations PDF

Description

Test your understanding of population genetics and the Hardy-Weinberg principle with this quiz for Biology 1120. Explore how evolutionary forces influence allele frequencies and the genetic variation within populations. Perfect preparation for your upcoming assessments with Professor Feely.

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