Hardy-Weinberg Equilibrium Quiz
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Questions and Answers

Which of the following conditions is NOT required for Hardy-Weinberg Equilibrium to be maintained?

  • Migration occurs (correct)
  • Large population size
  • Random mating
  • No natural selection

In Hardy-Weinberg Equilibrium, allele frequencies change over time.

False (B)

What is the formula to calculate allele frequencies in a population?

p + q = 1

The rejection of the null hypothesis when it is true is known as a type ______ error.

<p>I</p> Signup and view all the answers

Match the following Hardy-Weinberg conditions with their descriptions:

<p>Large population size = Minimizes genetic drift No natural selection = Equal chances for all genotypes No migration = No new alleles introduced Random mating = Mates chosen without bias</p> Signup and view all the answers

What probability threshold is commonly used to test the null hypothesis in this context?

<p>5% (C)</p> Signup and view all the answers

Type II error occurs when the null hypothesis is accepted despite being false.

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

What is the formula used for calculating the chi-square value?

<p>(observed - expected)² / expected</p> Signup and view all the answers

A trait that is influenced by multiple genes simultaneously is called a ______ trait.

<p>polygenic</p> Signup and view all the answers

Match the following terms with their descriptions:

<p>Pleiotropic genes = One gene influences multiple traits Quantitative trait = Trait affected by many genes and environment Polygenic traits = Traits influenced by multiple genes simultaneously Degrees of freedom = Number of classes minus number of alleles</p> Signup and view all the answers

What is a primary benefit of sexual reproduction?

<p>Increased genetic diversity (D)</p> Signup and view all the answers

Asexual reproduction leads to greater genetic diversity in populations.

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

Define parthenogenesis.

<p>Reproduction from an unfertilized egg.</p> Signup and view all the answers

In sexual reproduction, only ______% of a parent's genes are passed on to the offspring.

<p>50</p> Signup and view all the answers

Match the following types of reproduction with their descriptions:

<p>Sexual reproduction = Involves two parents and genetic recombination Asexual reproduction = Involves one parent without genetic variability Parthenogenesis = Involves reproduction without fertilization DNA repair hypothesis = Explains the ability to repair damaged genetic material</p> Signup and view all the answers

Which of the following is a cost of asexual reproduction?

<p>Increased competition for resources (B)</p> Signup and view all the answers

The parasitic DNA hypothesis suggests that sexual reproduction has no impact on the spread of parasitic genetic elements.

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

What is one hypothesis for the origin of sex?

<p>Parasitic DNA hypothesis or DNA repair hypothesis.</p> Signup and view all the answers

What is directional selection?

<p>Selection that favors one trait over another (A)</p> Signup and view all the answers

Stabilizing selection favors extreme phenotypes in a population.

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

What are cryptic species?

<p>Species that are indistinguishable morphologically but divergent in traits like calls or odors.</p> Signup and view all the answers

______ speciation occurs when geographic barriers separate populations.

<p>Allopatric</p> Signup and view all the answers

Match the type of selection with its description:

<p>Directional Selection = Favors one extreme phenotype Stabilizing Selection = Favors intermediate phenotypes Disruptive Selection = Favors two or more extreme phenotypes</p> Signup and view all the answers

Which species concept emphasizes reproductive isolation?

<p>Biological species concept (D)</p> Signup and view all the answers

Polyploidy refers to organisms with a complete set of chromosomes that is less than two.

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

What is the outcome of hybridization between genetically distinct populations?

<p>Production of hybrid offspring.</p> Signup and view all the answers

The divergence of a clade into populations adapted to various ecological niches is called _______.

<p>adaptive radiation</p> Signup and view all the answers

Match the mechanism of evolutionary isolation with its description:

<p>Allopatric Model = Geographic isolation Sympatric Model = Reproduction without physical barriers Dispersal Model = Population divides due to migration</p> Signup and view all the answers

What is the effect of natural selection on populations?

<p>Enables survival of better-adapted traits (D)</p> Signup and view all the answers

Species concepts do not account for historical or extinct populations.

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

What can lead to reproductive isolation in sympatric speciation?

<p>Different food preferences and mating behaviors.</p> Signup and view all the answers

What is the main purpose of sexual reproduction in relation to genetic diversity?

<p>To maintain and enhance genetic diversity (C)</p> Signup and view all the answers

Muller’s ratchet occurs in sexually reproducing organisms.

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

What process describes competition among males for access to females?

<p>Intrasexual selection</p> Signup and view all the answers

The _____ hypothesis suggests that females choose males with genes that will increase the quality of their offspring.

<p>good gene</p> Signup and view all the answers

Match the following reproductive strategies with their definitions:

<p>Intrasexual selection = Competition among males for mating rights Intersexual selection = Selection based on traits attractive to the opposite sex Cryptic female choice = Biasing paternity towards certain males post-mating Runaway sexual selection = Preference for extravagant traits leading to maladaptive traits</p> Signup and view all the answers

Which of these is an example of sexual dimorphism?

<p>Males have bright feathers; females are brown (A)</p> Signup and view all the answers

Sexual reproduction can lead to a decrease in genetic diversity in a population.

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

What does linkage disequilibrium refer to?

<p>Increasing association of alleles at different loci</p> Signup and view all the answers

One sex typically produces numerous small gametes () while the other sex produces fewer larger gametes ().

<p>male, female</p> Signup and view all the answers

Which hypothesis explains why females may prefer mates with exaggerated traits?

<p>Handicap principle (C)</p> Signup and view all the answers

Sperm competition occurs when females have only one mating partner.

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

What is the effect of sexual selection on male traits?

<p>Exaggeration of traits favored by females</p> Signup and view all the answers

The _____ principle explains how animals signal their fitness through costly traits.

<p>handicap</p> Signup and view all the answers

Match the sexual selection mechanisms with their descriptions:

<p>Intrasexual selection = Competing individuals of the same sex Cryptic female choice = Post-mating bias towards certain males Runaway sexual selection = Trait preference becomes exaggerated over time Intersexual selection = Individuals choose mates based on specific traits</p> Signup and view all the answers

What is one of the consequences of Muller’s ratchet in asexual populations?

<p>Buildup of deleterious mutations (B)</p> Signup and view all the answers

Flashcards

Hardy-Weinberg Equilibrium

A theoretical model in population genetics that describes a population where allele and genotype frequencies remain constant over generations. It serves as a baseline to understand how evolution affects populations.

Allele Frequencies

The proportion of each allele (different forms of a gene) within a population.

Genotype Frequencies

The proportion of each possible genotype combination (like AA, Aa, aa) within a population.

No Natural Selection

One of the conditions for Hardy-Weinberg Equilibrium, where all genotypes have equal chances of survival and reproduction. This means no specific traits are favored.

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Type I Error

A statistical error where you reject the null hypothesis (Hardy-Weinberg Equilibrium) when it is actually true.

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Chi-Square Test

A statistical test used to determine if observed genotype frequencies in a population significantly differ from expected frequencies under Hardy-Weinberg equilibrium.

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Degrees of Freedom (df)

The number of values that can vary freely in a chi-square test. Calculated as the number of classes being compared minus the number of alleles.

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Pleiotropic Genes

Genes that influence multiple different traits.

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Polygenic Traits

Traits controlled by multiple genes working together.

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Quantitative Traits

Traits that are influenced by both genes and environmental factors, resulting in a range of values.

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Sex vs. Gender

Sex refers to biological differences between males and females, while gender is how someone identifies their own masculinity or femininity.

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Sexual Reproduction: Costs

Sexual reproduction has disadvantages like the risk of losing beneficial gene combinations due to recombination, the energy and time needed for finding mates, exposure to diseases and parasites, increased predation, and only 50% of your genes being passed on.

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Sexual Reproduction: Benefits

Sexual reproduction benefits include increased genetic diversity within a population, disease resistance, and facilitating natural selection, enabling beneficial traits to be passed on.

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Asexual Reproduction: Costs

Asexual reproduction has drawbacks like lack of variation within the population, susceptibility to environmental changes and diseases, passing on harmful mutations, and increased competition for resources.

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Asexual Reproduction: Benefits

Asexual reproduction is advantageous due to rapid population growth, which can be useful for colonizing new areas, lower energy needs due to only one parent, preservation of beneficial traits, and no requirement for a mate.

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Parthenogenesis

Parthenogenesis is a form of asexual reproduction where offspring develop from unfertilized eggs. This means females can reproduce without mating.

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Parasitic DNA Hypothesis

This hypothesis suggests that sexual reproduction evolved to help spread parasitic DNA elements, because these elements benefit from shuffling genes in their host.

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DNA Repair Hypothesis

This hypothesis proposes that sexual reproduction evolved to aid in repairing damaged DNA through homologous recombination, a process that relies on having two copies of each gene.

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Directional Selection

A type of natural selection where one extreme trait is favored over others, causing the population to shift in that direction.

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Stabilizing Selection

Natural selection that favors the average or moderate traits, reducing variation in a population.

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Disruptive Selection

Natural selection that favors two or more extreme phenotypes, leading to increased diversity within a population.

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Biological Species Concept

Defines species as groups of organisms that can interbreed and produce fertile offspring, but are reproductively isolated from other groups.

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Morphological Species Concept

Identifies species based on physical characteristics, focusing on similarities in appearance.

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Phylogenetic Species Concept

Defines species as the smallest group of organisms that share a unique common ancestor, based on genetic relationships.

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Cryptic Species

Species that are indistinguishable by appearance, but are genetically distinct and reproductively isolated.

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Speciation

The process of creating new species by splitting a population into two or more genetically independent lineages.

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Allopatric Speciation

Speciation that occurs when two populations are geographically isolated, preventing gene flow and leading to divergence.

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Sympatric Speciation

Speciation that occurs within the same geographical area, due to factors like resource partitioning or behavioral differences.

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Dispersal Model

A mechanism of allopatric speciation where a group of individuals migrates to a new location, establishing a new, isolated population.

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Vicariance Model

A mechanism of allopatric speciation where a physical barrier arises, dividing a previously continuous population into isolated groups.

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Polyploidy

The condition of having more than two complete sets of chromosomes, often leading to reproductive isolation.

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Genetic Drift

Random changes in allele frequencies within a population, due to chance events, particularly in small populations.

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Adaptive Radiation

The rapid diversification of a single lineage into multiple species that occupy different ecological niches.

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Muller's Ratchet

A genetic process in asexual organisms where harmful mutations accumulate over time due to the lack of recombination.

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Linkage Disequilibrium

When DNA sequences are close together and therefore inherited together more often than expected by chance.

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Linkage Equilibrium

When DNA sequences are far apart and inherited independently of each other.

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Sex Breaks the Ratchet

Sexual reproduction shuffles genes, preventing the buildup of harmful mutations that occurs in asexual organisms.

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Red Queen Hypothesis

Sexual reproduction helps organisms adapt to constantly changing environments, especially those with parasites.

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Sexual Dimorphism

Differences in physical characteristics between males and females of the same species.

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Intrasexual Selection

Competition between members of the same sex for mates.

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Sperm Competition

Competition between sperm from different males to fertilize a female's egg.

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Alternative Mating Strategies

Different ways males can secure mates, like sneaking or mimicking females.

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Intersexual Selection

One sex chooses mates based on certain traits.

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Direct Benefits

Females choosing mates based on resources like territory or parental care.

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Good Genes Hypothesis

Females choose mates with genetic advantages that improve offspring quality.

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Handicap Principle

Traits that are costly to develop signal good genes to potential mates.

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Sexy Son Hypothesis

Females choose mates whose genes will produce attractive male offspring.

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Runaway Sexual Selection

A trait becomes more exaggerated over time because it makes individuals more attractive to mates.

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Study Notes

Population Genetics

  • Hardy-Weinberg Equilibrium is a null model used to compare real data to hypothetical data to understand how trait frequencies change in populations, or how evolution operates.
  • Allele frequencies remain constant over time.
  • Specific conditions for equilibrium include: large population size to minimize genetic drift; no natural selection; no migration; no mutations; and random mating.

Calculating Frequencies

  • Allele frequencies (p and q) add up to 1.
  • Genotype frequencies are calculated as follows: q² + 2pq + p² = 1

Statistical Errors

  • Type I error (alpha error): rejecting a true null hypothesis. An acceptable probability of this is 5% (α = 0.05).
  • Type II error: failing to reject a false null hypothesis.

Chi-Square Analysis

  • Used to determine if populations are in Hardy-Weinberg equilibrium.
  • Compares observed values to expected values.
  • Degrees of freedom are calculated by subtracting the number of alleles from the number of classes.
  • A chi-square value less than the critical value indicates equilibrium.

Modes of Selection

  • Directional Selection: favors one extreme trait over another (e.g., giraffes with longer necks).
  • Stabilizing Selection: favors intermediate traits (e.g., robins laying four eggs).
  • Disruptive Selection: favors both extreme traits (e.g., gray and white rabbits).

Species Concept & Speciation

  • Three species concepts exist: Biological (reproductive isolation); Morphological (physical traits); and Phylogenetic (smallest monophyletic group).
  • Allopatric speciation: new species evolve due to geographic isolation (e.g., dispersal or vicariance).
  • Sympatric speciation: new species evolve without geographic isolation.
  • Mechanisms for evolutionary isolation: Allopatric model-geographic isolation, dispersal model-population physically separated by geographical barriers; Vicariance model—population is divided by a developing barrier.

Evolution of Sex

  • Sex is the biological distinction between males and females (chromosomes, hormones, anatomy).
  • Gender refers to self-identification (male, female, or otherwise).
  • Sexual reproduction involves combination of genes causing genetic diversity, and asexual reproduction does not.
  • Costs of sexual reproduction: energy & time in finding mates, risk of diseases.
  • Benefits of sexual reproduction: diverse genes, disease resistance facilitating natural selection.

Sexual Selection

  • Sexual dimorphism: males and females exhibit different physical traits.
  • Intrasexual selection: competition among members of the same sex (e.g., males fighting for mates like in elks, flies and moose).
  • Intersexual selection: choice of one sex by the other (e.g., peacocks' tails).
  • Good gene hypothesis: choosing a mate with beneficial traits.
  • Handicap principle: males with traits that diminish survival are more attractive to females because such fitness makes them healthier.
  • Sexy son hypothesis: females choose males that will make their sons attractive.

Cryptic Female Choice

  • Females exert choice after mating.
  • Mechanisms include behavioral, physiological, or morphological processes to influence which sperm fertilizes their eggs.

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Population Genetics - Evolution Exam #3 PDF

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Test your knowledge of the Hardy-Weinberg Equilibrium, including its conditions, principles, and related statistical concepts. This quiz covers key formulas, errors in hypothesis testing, and the influence of multiple genes on traits. Perfect for students studying genetics.

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