Genetics Chapter 13: Evolutionary Synthesis
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Questions and Answers

Which of the following statements best describes meiotic drive?

  • Meiotic drive influences the expression of all alleles equally.
  • It only occurs in plants.
  • Alleles segregate independently during meiosis.
  • One allele is favored in the process of meiosis, leading to unequal segregation. (correct)
  • Pleiotropy occurs when one gene affects multiple phenotypes.

    True (A)

    What phenomenon describes genes that are inherited together due to their physical proximity on a chromosome?

    Physical linkage

    The ABO blood type system is an example of more than ______ alleles at a gene/locus.

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

    Which term refers to the effect when a single allele causes one genetic disorder, but its dominance or recessiveness may vary depending on the phenotype examined?

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

    Alleles at different loci always assort independently.

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

    Match the following terms with their correct definitions:

    <p>Pleiotropy = One gene affects multiple phenotypes Meiotic drive = Unequal segregation of alleles during meiosis Physical linkage = Genes inherited together due to proximity Alleles = Different versions of a gene</p> Signup and view all the answers

    Name a rare but dominant allele that can cause a condition in humans.

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

    What is the probability of producing red-flower offspring from the genotypes RR, Rr, or rR?

    <p>0.75 (A)</p> Signup and view all the answers

    All offspring genotypes lead to the same phenotype.

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

    What is the probability of obtaining the genotype AABb from a double heterozygote (AaBb) mating with an AaBB individual?

    <p>0.125</p> Signup and view all the answers

    Mendel’s law of __________ dominance describes a scenario where a dominant trait is completely expressed over a recessive one.

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

    Match the type of dominance with its description:

    <p>Complete dominance = Dominant allele fully masks recessive allele Incomplete dominance = Intermediate phenotype between two alleles Co-dominance = Both alleles express distinctly in the phenotype Recessive dominance = Only expressed when two copies are present</p> Signup and view all the answers

    In a cross between Aa and Aa, what is the expected frequency of the homozygous recessive genotype?

    <p>0.25 (A)</p> Signup and view all the answers

    Environmental factors can have no impact on genetic expression.

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

    What is the Hardy-Weinberg principle used for?

    <p>To calculate allele and genotype frequencies in a population under ideal conditions.</p> Signup and view all the answers

    What is the primary effect of epistasis in genetics?

    <p>The effect of one locus can alter the expression of another locus (C)</p> Signup and view all the answers

    All traits are governed solely by a single locus.

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

    What phenomenon can produce missing gamete types during meiosis?

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

    The human genome consists of approximately ___ genes.

    <p>30,000</p> Signup and view all the answers

    Match the terms with their definitions:

    <p>Allele Frequency = The proportion of a specific allele among all allele copies in a population Genotype Frequency = The proportion of a specific genotype among the total population Recombination = The process where genetic material is exchanged between homologous chromosomes Epistasis = The interaction between genes at different loci affecting the phenotype</p> Signup and view all the answers

    What is the relationship between the probability of recombination events and the distance between loci on a chromosome?

    <p>It increases as the distance increases (A)</p> Signup and view all the answers

    Phenotypic expression can be simply determined by counting allele frequencies.

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

    What type of disorders are often influenced by recessive alleles and require two copies for expression?

    <p>Recessive Genetic Disorders</p> Signup and view all the answers

    Which of the following processes contributes to microevolution?

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

    Microevolution requires the presence of more than one allele at a locus within a population.

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

    Name one of the four processes that can cause microevolution.

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

    Microevolution is the result of __________ occurring within populations.

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

    Match the following terms with their descriptions:

    <p>Mutation = Change in a DNA sequence Gene flow = Movement of genes between populations Genetic drift = Random changes in allele frequencies Natural selection = Differential survival and reproduction</p> Signup and view all the answers

    What is the primary focus of microevolution?

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

    Gene flow and mutation are identical in their roles in altering allele frequencies.

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

    What term describes the decline in fitness of a population due to inbreeding?

    <p>inbreeding depression</p> Signup and view all the answers

    Mutation can be classified as beneficial, neutral, or ________ in terms of its effects on fitness.

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

    Match the terms with their definitions regarding genetic concepts:

    <p>Natural selection = Process where organisms better adapted to their environment tend to survive and reproduce Genetic drift = Random changes in allele frequencies, especially in small populations Gene flow = Transfer of genetic variation between populations Inbreeding = Breeding of closely related individuals, increasing homozygosity</p> Signup and view all the answers

    Which of the following is a potential effect of genetic drift?

    <p>Loss of alleles from a small population (A)</p> Signup and view all the answers

    Fitness only refers to an organism's ability to survive.

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

    What is the role of spatially varying selection in local adaptation?

    <p>It allows populations to adapt to different environmental conditions that vary across regions.</p> Signup and view all the answers

    What primarily causes changes in allele frequencies in finite populations?

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

    Larger populations experience stronger genetic drift than smaller populations.

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

    What is the effect of genetic drift on genetic variation?

    <p>It reduces genetic variation by causing alleles to be lost and decreasing heterozygosity.</p> Signup and view all the answers

    In genetics, the sampling variation inherent in a finite sample leads to differences in allele frequencies across __________.

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

    Match the following scenarios with their effects on allele frequency:

    <p>Large population size = Weaker genetic drift Small population size = Stronger genetic drift Random mating = Smaller deviations from HW expectations Gene flow = Reduces divergence between populations</p> Signup and view all the answers

    Which of the following directly influences the magnitude of change due to genetic drift?

    <p>Population size (C)</p> Signup and view all the answers

    What is genetic drift?

    <p>Genetic drift is a process where allele frequencies in a population change due to random sampling variation.</p> Signup and view all the answers

    Genetic drift can overwhelm natural selection in small populations.

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

    What is the effect of inbreeding on genotype frequencies?

    <p>Increases the frequency of homozygotes (D)</p> Signup and view all the answers

    Inbreeding depression refers to an increase in fitness due to inbreeding.

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

    What is the common consequence of inbreeding in small populations?

    <p>Loss of genetic variation</p> Signup and view all the answers

    Inbreeding causes an increase in _____, which can decrease overall fitness.

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

    Match the following terms related to inbreeding with their descriptions:

    <p>Inbreeding = Mating between related individuals Homozygosity = Increase in identical alleles Inbreeding Depression = Decrease in fitness due to inbreeding Genetic Drift = Random changes in allele frequencies</p> Signup and view all the answers

    Which of the following effects can inbreeding have on broader biological fields?

    <p>Can impact conservation biology (C)</p> Signup and view all the answers

    Inbreeding effects on genotype frequencies are permanent and cannot revert back.

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

    Name a historical figure often associated with the negative effects of inbreeding.

    <p>Charles II of Spain</p> Signup and view all the answers

    What is necessary for natural selection to occur?

    <p>Individual variation in a trait and non-random associations with reproductive success (A)</p> Signup and view all the answers

    Natural selection is the only mechanism of evolution.

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

    What is meant by 'Darwinian fitness'?

    <p>The reproductive success of an individual measured by the number of offspring it produces.</p> Signup and view all the answers

    Natural selection acts on __________, which are influenced by genetic variation.

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

    Match the evolutionary mechanism with its description:

    <p>Mutation = Change in DNA sequence that may introduce new traits Gene flow = Movement of alleles between populations Genetic drift = Random changes in allele frequencies due to chance Natural selection = Process where traits enhance survival and reproduction become more common</p> Signup and view all the answers

    What are the three conditions necessary for natural selection to produce evolutionary change?

    <p>Variation, non-random association, heritability (D)</p> Signup and view all the answers

    Only advantageous phenotypes can be passed on through natural selection.

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

    How does genetic drift affect allele frequencies in a population?

    <p>Genetic drift can cause random changes in allele frequencies, leading to a loss of genetic variation.</p> Signup and view all the answers

    The trait's contribution to the next generation is referred to as its __________.

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

    Which of the following statements best represents the outcome of natural selection?

    <p>The distribution of trait values will change across generations. (B)</p> Signup and view all the answers

    What does setting migration to 'island' imply in a population study?

    <p>Migration occurs equally among all populations. (C)</p> Signup and view all the answers

    A severe decrease in population size can enhance genetic drift.

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

    What is a population bottleneck?

    <p>A rapid decrease in population size that reduces genetic variation.</p> Signup and view all the answers

    The probability of an allele eventually getting fixed by drift is equal to its current ________ frequency.

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

    Match the following health conditions with their associated populations:

    <p>Ellis-van Creveld syndrome = Pennsylvania Amish Myotonic dystrophy = Québécois Tay-Sachs disease = Ashkenazi Jews Polydactyly = Isolated populations</p> Signup and view all the answers

    Which of the following factors can lead to a population bottleneck?

    <p>Environmental changes (C)</p> Signup and view all the answers

    Founder events can have negative consequences for population persistence.

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

    What is the effect of increased gene flow on allele frequencies among populations?

    <p>It reduces divergence among populations.</p> Signup and view all the answers

    What term is used to describe random mating in a population?

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

    Non-random mating affects allele frequencies in a population.

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

    Which of the following best defines microevolution?

    <p>Changes in allele frequency across generations. (C)</p> Signup and view all the answers

    Gene flow and mutation serve identical roles in altering allele frequencies.

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

    What are two forms of non-random mating?

    <p>Inbreeding and assortative mating</p> Signup and view all the answers

    Mating that occurs between individuals of different phenotypes is called ________ mating.

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

    Match the types of mating with their definitions:

    <p>Inbreeding = Mating between closely related individuals Assortative mating = Mating with similar phenotype individuals Disassortative mating = Mating with different phenotype individuals Outbreeding = Mating between individuals less related than expected</p> Signup and view all the answers

    What is the primary impact of population bottlenecks?

    <p>Reduction in allele frequency variability. (B)</p> Signup and view all the answers

    Natural selection only affects phenotypic variations that are genetically inherited.

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

    Identify a mechanism that has evolved to reduce the likelihood of inbreeding.

    <p>Dispersal of individuals</p> Signup and view all the answers

    Which of the following processes is NOT one of the four causes of microevolution?

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

    Microevolution leads directly to macroevolution.

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

    Microevolution requires genetic variation, meaning there must be more than one ______ at a locus in a population.

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

    Match the following microevolutionary processes with their definitions:

    <p>Mutation = Change in genetic material Gene flow = Transfer of alleles between populations Genetic drift = Random changes in allele frequencies Natural selection = Differential survival and reproduction</p> Signup and view all the answers

    What is the term used to describe the decrease in fitness due to an increase in homozygosity resulting from inbreeding?

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

    Inbreeding can lead to an increase in heterozygotes within a population.

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

    What genetic consequence does inbreeding primarily cause in a population?

    <p>Increase in homozygosity</p> Signup and view all the answers

    The phenomenon where a loss of genetic variation in small populations can be worsened by inbreeding is known as __________.

    <p>genetic drift</p> Signup and view all the answers

    Match the following outcomes of inbreeding with their effects:

    <p>Increase in homozygosity = Decreased genetic variation Inbreeding depression = Decreased fitness Loss of allelic diversity = Increased vulnerability to extinction Ephemeral effects = Restoration of Hardy-Weinberg frequencies</p> Signup and view all the answers

    Which scenario can result from inbreeding depression?

    <p>Reduced fertility in offspring (A)</p> Signup and view all the answers

    One or a few generations of random mating can restore the Hardy-Weinberg expected genotype frequencies after inbreeding.

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

    What does an increase in homozygosity due to inbreeding typically lead to in terms of population fitness?

    <p>Decrease in fitness</p> Signup and view all the answers

    What is primarily responsible for random changes in allele frequencies in finite populations?

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

    Smaller populations experience weaker genetic drift than larger populations.

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

    Explain how genetic drift can lead to the loss of genetic variation in a population.

    <p>Genetic drift causes random changes in allele frequencies, which can lead to the fixation or loss of alleles, thereby reducing genetic variation.</p> Signup and view all the answers

    The decline in fitness of a population due to inbreeding is known as __________.

    <p>inbreeding depression</p> Signup and view all the answers

    Match the following concepts with their effects:

    <p>Genetic drift = Random change in allele frequencies Natural selection = Directional change based on fitness Gene flow = Introduction of new alleles Mutation = Creation of new genetic variants</p> Signup and view all the answers

    Which of the following is a consequence of genetic drift in small populations?

    <p>Fixation of deleterious alleles (D)</p> Signup and view all the answers

    The process of genetic drift can cause populations to diverge from each other.

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

    What is the effect of setting the migration rate to 0 in a population with drift?

    <p>Decreased gene flow between populations (A)</p> Signup and view all the answers

    As population size (N) increases, the magnitude of change in allele frequency due to drift becomes __________.

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

    A population bottleneck increases genetic variation within a population.

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

    What is one example of a disorder that can have increased frequency due to a bottleneck?

    <p>Tay-Sachs disease</p> Signup and view all the answers

    The probability of an allele eventually fixing due to drift is equal to its current ________.

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

    Match the following effects with their causes in population genetics:

    <p>Bottleneck = Severe decrease in population size Founder event = Colonization by a small group Gene flow = Migration of individuals between populations Genetic drift = Random changes in allele frequencies</p> Signup and view all the answers

    Which migration rate would likely lead to the most allele frequency divergence among populations?

    <p>0 (C)</p> Signup and view all the answers

    Increased gene flow can enhance local adaptation.

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

    What can cause genetic drift to have a more pronounced effect in a population?

    <p>Small population size</p> Signup and view all the answers

    Which of the following processes does NOT contribute to microevolution?

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

    Microevolution can occur without genetic variation.

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

    Name one of the four processes that can lead to microevolution.

    <p>Mutation, gene flow, genetic drift, or natural selection</p> Signup and view all the answers

    The long-term and higher taxonomic consequences of microevolution are referred to as __________.

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

    Match the following processes with their effects on allele frequencies:

    <p>Mutation = Introduction of new alleles Gene flow = Transfer of alleles between populations Genetic drift = Random changes in allele frequencies Natural selection = Differential survival and reproduction</p> Signup and view all the answers

    What is the term used to describe the decrease in fitness as a consequence of inbreeding?

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

    Inbreeding increases the frequency of heterozygotes in a population.

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

    What effect does inbreeding have on genetic variation in small populations?

    <p>It can exacerbate the loss of genetic variation.</p> Signup and view all the answers

    Inbreeding leads to an increase in _______ across the genome.

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

    Which of the following statements is true regarding the effects of inbreeding?

    <p>Inbreeding can impact human health. (A)</p> Signup and view all the answers

    One or a few generations of random mating can restore Hardy-Weinberg expected genotype frequencies.

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

    Name one consequence of inbreeding depression.

    <p>Decreased fitness.</p> Signup and view all the answers

    What is the primary mechanism by which gene flow can impede local adaptation?

    <p>Introduces maladaptive alleles (C)</p> Signup and view all the answers

    The dominance hypothesis suggests that deleterious alleles are typically dominant within a population.

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

    What term describes the negative impact on fitness from mating between populations with different adaptations?

    <p>Outbreeding depression</p> Signup and view all the answers

    When gene flow is __________, populations can diverge due to differing local selection pressures.

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

    Match the types of gene flow with their effects:

    <p>High gene flow = Promotes adaptation Low gene flow = Hinders local adaptation Gene flow = Homogenizes populations Outbreeding depression = Reduces fitness</p> Signup and view all the answers

    Which of the following statements about gene flow is true?

    <p>Gene flow can both enhance and reduce adaptation. (B)</p> Signup and view all the answers

    Gene flow can lead to the establishment of a single panmictic population if it is high enough.

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

    Explain a way in which gene flow can promote adaptation of a population to its environment.

    <p>By spreading beneficial alleles among populations.</p> Signup and view all the answers

    What happens to genetic divergence among populations when the migration rate is set to 0?

    <p>Divergence increases due to lack of gene flow (D)</p> Signup and view all the answers

    Population bottlenecks enhance genetic variation.

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

    What is the primary consequence of a founder event?

    <p>Reduction in genetic variation due to a small initial population.</p> Signup and view all the answers

    An increase in the frequency of a deleterious mutation in an isolated population can have human health implications, such as ________ in the Amish community.

    <p>Ellis-van Creveld syndrome</p> Signup and view all the answers

    Match the following terms related to genetic drift with their definitions:

    <p>Genetic Drift = Change in allele frequencies due to random sampling Population Bottleneck = Drastic reduction in population size leading to loss of genetic diversity Founder Effect = Genetic variation resulting from a new population founded by a small number of individuals Allele Fixation = The point at which a specific allele becomes the only variant in a population</p> Signup and view all the answers

    Which migration rate is expected to produce the least divergence among populations?

    <p>0.1 (A)</p> Signup and view all the answers

    Increased genetic drift has no effect on allele frequencies in large populations.

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

    Give an example of a condition that has become more prevalent due to a bottleneck effect.

    <p>Tay-Sachs disease</p> Signup and view all the answers

    What is the primary consequence of genetic drift in small populations?

    <p>Increased fixation of deleterious alleles (A)</p> Signup and view all the answers

    What term describes the randomness of allele frequency changes across generations?

    <p>genetic drift</p> Signup and view all the answers

    The magnitude of genetic drift is __________ related to population size.

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

    Which factor primarily causes changes in allele frequencies in finite populations?

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

    Match the terms with their respective effects:

    <p>Genetic Drift = Random changes in allele frequencies Natural Selection = Non-random changes favoring some alleles over others Gene Flow = Movement of alleles between populations Mutation = Creation of new alleles</p> Signup and view all the answers

    If random mating occurs, drift-induced deviations from Hardy-Weinberg expected genotype frequencies are usually __________.

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

    Name one scenario that can be simulated to observe the effects of genetic drift.

    <p>Population size variations such as N = 5000, 500, 50, 10</p> Signup and view all the answers

    Which of the following conditions is NOT necessary for natural selection to occur?

    <p>The trait must be dominant (B)</p> Signup and view all the answers

    Natural selection can cause allele frequencies to change across generations.

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

    Name one mechanism of microevolution.

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

    The term 'Darwinian fitness' refers to an individual's contribution to the ________ generation.

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

    Which of the following best describes genetic drift?

    <p>Random changes in allele frequencies in small populations (D)</p> Signup and view all the answers

    Fitness is solely determined by an organism's ability to survive.

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

    What is the primary effect of inbreeding on a population?

    <p>Inbreeding depression</p> Signup and view all the answers

    Natural selection leads to the evolution of traits that increase an organism's ________ in a given environment.

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

    Which of the following is a potential effect of gene flow?

    <p>Increased genetic diversity in adjacent populations (C)</p> Signup and view all the answers

    Flashcards

    Meiotic Drive

    A phenomenon where a gene manipulates meiosis to favor the transmission of one allele over another.

    Independent Segregation

    The expected 50/50 chance of either allele being passed down.

    Physical Linkage

    A phenomenon where genes are close together on a chromosome, leading to inheritance patterns correlated with the proximity of the genes.

    Pleiotropy

    A single gene affecting multiple traits or phenotypes.

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    Multiple Alleles

    More than two alleles for a gene.

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    Dominance/Recessiveness

    The way alleles interact to produce a phenotype; it doesn't predict the frequency of the allele.

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    Test Cross

    A cross between an organism with an unknown genotype and an organism with a known genotype (usually homozygous recessive) to determine the unknown genotype.

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    Linked Genes

    Genes located close together on a chromosome that are likely to be inherited together.

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    Gene location on chromosome

    Many genes are located on a single chromosome.

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    Non-independent inheritance

    Traits aren't always inherited independently. Some traits are linked and inherit together more often than not due to their proximity on a chromosome.

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    Recombination

    Genetic material swapping during meiosis, creating new combinations of traits.

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    Recombination and distance

    The distance between genes on a chromosome affects the chance of recombination.

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    Epistasis

    One gene affects the expression of another gene.

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    Chromosome Pairs

    Homologous chromosomes, which are two matching pairs of chromosomes, line up closely together on the cellular spindle during meiosis.

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    Alleles

    Different forms of a gene.

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    Multiple chromosome genes

    A single chromosome contains a large amount of genes, not just one.

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    Offspring Genotype

    The genetic makeup of an offspring

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    Mutually Exclusive

    Different genotypes cannot occur together. (e.g., RR and rr cannot coexist)

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    Probability of red flower offspring

    The likelihood of an offspring having red flowers (given the possible genotypes)

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    Probability for AABb offspring

    The chance of an offspring inheriting an AABb genotype from AaBb and AaBB parents

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    Independent Assortment

    The inheritance of alleles for one gene does not influence the inheritance of alleles for another gene.

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    Incomplete Dominance

    A genetic situation in which neither allele is completely dominant over the other resulting in an intermediate phenotype

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    Co-dominance

    Both alleles contribute equally to the offspring and both traits are visible

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    Double Heterozygote

    An individual carrying two different heterozygous alleles (e.g., AaBb)

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    Microevolution

    Changes in allele frequencies within a population across generations. Focuses on variation within a species and shorter timeframes.

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    Macroevolution

    Evolutionary changes above the species level. Focuses on the origin of new species and diversification over long periods.

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    Genetic Variation

    Differences in genes and traits within a population.

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    Allele Frequency

    The proportion of a specific allele in a population.

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    What are the sources of genetic variation?

    Mutations, gene flow, and genetic drift are the primary sources of genetic variation.

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    Mutation

    A change in the DNA sequence.

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    Gene Flow

    The movement of genes between populations.

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    Genetic Drift

    Random changes in allele frequencies due to chance events.

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    Microevolution: What's required?

    Microevolution, the change in allele frequencies within a population, requires genetic variation. Meaning, there must be more than one allele for a particular gene present in the population.

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    Microevolution: What are the processes?

    Four main processes drive microevolution: mutation, gene flow, genetic drift, and natural selection. These processes, along with genetic variation, cause the shift in allele frequencies over time.

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    Macroevolution: What is it?

    Macroevolution is the large-scale evolutionary change, often happening over longer periods, and resulting in significant changes like the emergence of new species or major evolutionary trends.

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    What is the relationship between micro and macroevolution ?

    Macroevolution is essentially the cumulative effect of microevolution over extended periods. Small changes in allele frequencies within populations (microevolution) can eventually lead to larger-scale evolutionary transformations (macroevolution).

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    What are the mathematical frameworks?

    Quantitative genetics and population genetics use mathematical models to predict and study the effects of evolutionary processes like mutation, selection, drift, and gene flow on both Mendelian traits and quantitative traits.

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    Inbreeding

    Mating between related individuals, increasing homozygosity and decreasing heterozygosity.

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    Inbreeding Depression

    Reduced fitness due to increased homozygosity resulting from inbreeding.

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    Homozygosity

    Having two identical alleles for a gene.

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    Heterozygosity

    Having two different alleles for a gene.

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    Hardy-Weinberg Equilibrium

    A theoretical model where allele and genotype frequencies remain constant across generations.

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    Conservation Biology

    The study and application of scientific principles to preserve biodiversity.

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    Human Health

    The state of physical, mental, and social well-being.

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    Natural Selection

    A process where individuals with traits that increase their survival and reproduction in a specific environment are more likely to pass on their genes.

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    Darwinian Fitness

    The reproductive success of an individual, measured by the number of offspring it produces.

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    What are the conditions for natural selection?

    Natural selection requires variation in a trait, a non-random link between the trait and reproductive success, and the trait must be heritable.

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    Adaptation

    A trait that enhances an organism's survival and reproduction in a specific environment.

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    How does natural selection act?

    Natural selection acts on the phenotypes of individuals, which are influenced by their underlying genotypes.

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    What is the outcome of natural selection?

    Natural selection leads to changes in allele frequencies across generations, shifting the distribution of traits in a population.

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    DDT Resistance in Insects

    An example of how natural selection can lead to rapid evolutionary change. Insects that had a genetic variation allowing them to survive the pesticide became more frequent.

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    Finite Population

    A population with a limited number of individuals. This means that the genetic makeup of the next generation is influenced by a random sample of alleles from the previous generation.

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    Sampling Variation

    The difference between the true value of a population and the value observed in a finite sample. This causes allele frequencies to fluctuate in smaller populations.

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    Drift Strength

    The magnitude of change in allele frequencies due to genetic drift. Smaller populations experience stronger drift because random events have a bigger impact.

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    Drift and Genetic Variation

    Genetic drift generally reduces genetic variation within a population. This is because alleles are lost by chance, leading to a decrease in heterozygosity.

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    Drift and Population Divergence

    Genetic drift can cause populations to diverge from each other over time, especially in the absence of gene flow. This is because random changes in allele frequencies accumulate in isolated populations.

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    Drift and Deleterious Alleles

    In small populations, genetic drift can overwhelm natural selection. This means that harmful alleles can become more common, even though they reduce fitness.

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    HW Equilibrium and Drift

    Random mating in each generation helps to minimize the deviations from Hardy-Weinberg equilibrium (expected genotype frequencies) caused by genetic drift. However, drift still has an impact, especially in smaller populations.

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    Migration's Effect on Allele Frequencies

    Migration, or gene flow, is the movement of individuals between populations, which can alter allele frequencies. Higher migration rates lead to more gene flow and less divergence between populations.

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    Bottleneck Effect

    A sudden decrease in population size due to random events like disease or habitat loss, which can significantly reduce genetic variation and increase the impact of genetic drift.

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    Founder Effect

    A special case of a bottleneck where a small group of individuals establishes a new population, often in a new geographic location, leading to reduced genetic variation in the new population.

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    Deleterious Mutation

    A change in DNA sequence that is harmful or reduces an organism's fitness.

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    Mutation-Drift Interaction

    Bottlenecks can increase the frequency of deleterious mutations in isolated populations, as harmful alleles are more likely to become common by chance in a small population.

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    Human Health Implications of Bottlenecks

    Bottlenecks can have negative consequences for human health. Examples include increased rates of genetic disorders in specific populations.

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    Genetic Variation and Adaptation

    Genetic variation is crucial for a population's ability to adapt to changing environments. Bottlenecks and founder effects can limit this variation, making adaptation more challenging.

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    Fitness

    The reproductive success of an individual, measured by the number of offspring it produces.

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    What are the four processes of microevolution?

    Mutation, gene flow, genetic drift, and natural selection are the four main processes that drive changes in allele frequencies within a population.

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    What is the relationship between microevolution and macroevolution?

    Macroevolution is essentially the cumulative effect of microevolution over extended periods. Small changes in allele frequencies within populations (microevolution) can eventually lead to larger-scale evolutionary transformations (macroevolution).

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    Non-random mating

    Mating patterns where individuals choose partners based on factors other than random chance, such as relatedness or similarity in phenotype.

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    Assortative mating

    Individuals with similar phenotypes are more likely to mate than expected by chance.

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    Self-fertilization

    An organism fertilizes its own eggs, leading to increased homozygosity and a reduced genetic diversity.

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    Migration and Genetic Divergence

    Migration, or gene flow, is the movement of individuals between populations. Higher migration rates lead to more gene flow and less divergence in allele frequencies between populations.

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    What is the effect of inbreeding on genotype frequencies?

    Inbreeding increases the frequency of homozygous genotypes and decreases the frequency of heterozygous genotypes. This deviation from Hardy-Weinberg equilibrium is temporary, and random mating can restore expected genotype frequencies within a few generations.

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    How does inbreeding depression impact conservation biology?

    Inbreeding depression can exacerbate the loss of genetic variation in small populations, making it harder for them to adapt to environmental changes and increasing vulnerability to extinction.

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    Why is inbreeding depression relevant to human health?

    Inbreeding can increase the frequency of recessive genetic disorders, leading to health problems in individuals and affecting population health overall.

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    What is the relationship between inbreeding and genetic drift?

    Inbreeding can intensify the effects of genetic drift, as reduced genetic variation due to inbreeding makes populations more susceptible to random changes in allele frequencies.

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    What are the 4 processes of microevolution?

    Mutation, gene flow, genetic drift, and natural selection are the four main processes that drive changes in allele frequencies within a population.

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    How does microevolution relate to macroevolution?

    Macroevolution is essentially the cumulative effect of microevolution over extended periods. Small changes in allele frequencies within populations (microevolution) can eventually lead to larger-scale evolutionary transformations (macroevolution).

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    What is genetic variation?

    Differences in genes and traits within a population. This is essential for populations to adapt to their environment.

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    How does inbreeding impact genotype frequencies?

    Inbreeding causes a deviation from Hardy-Weinberg equilibrium. It increases the frequency of homozygous genotypes and decreases the frequency of heterozygous genotypes. However, this effect is temporary and can be reversed by a few generations of random mating.

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    Inbreeding and Conservation Biology

    Inbreeding can exacerbate the loss of genetic variation in small populations, making them less adaptable to environmental changes and more vulnerable to extinction.

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    Inbreeding and Human Health

    Inbreeding increases the frequency of recessive genetic disorders, which can lead to health problems for individuals and impact overall population health.

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    Inbreeding and Genetic Drift

    Inbreeding can intensify the effects of genetic drift. Reduced genetic variation from inbreeding makes populations more susceptible to random changes in allele frequencies.

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    What are the consequences of inbreeding depression?

    Inbreeding depression leads to reduced fitness in populations, making individuals less likely to survive and reproduce. This can have significant consequences for the long-term viability of populations.

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    Why is inbreeding depression an important concept?

    Inbreeding depression highlights the importance of genetic diversity for the long-term health of populations. Understanding inbreeding depression is crucial for conservation efforts and can be applied to human health issues as well.

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    Dominance Hypothesis

    Explains inbreeding depression by stating that deleterious alleles (harmful alleles) are often recessive and become more prevalent in homozygous individuals due to inbreeding.

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    How does gene flow affect local adaptation?

    Gene flow can both promote and hinder local adaptation. It can spread beneficial alleles, but also introduce maladaptive ones from other populations.

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    Local Adaptation

    A population adapting to its specific environment, leading to differences between populations in different environments.

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    Why is gene flow important for populations?

    Gene flow is essential for maintaining genetic diversity and preventing populations from becoming too isolated, reducing their ability to adapt to environmental changes.

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    What is the effect of high gene flow?

    High gene flow can homogenize populations, reducing genetic differences between them. This can hinder local adaptation but also promote the spread of beneficial alleles.

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    Conditions for Natural Selection

    Natural selection requires variation in a trait, a non-random link between the trait and reproductive success, and the trait must be heritable.

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    Natural Selection Acts on Phenotypes

    Natural selection acts on the phenotypes of individuals, which are influenced by their underlying genotypes.

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    Outcome of Natural Selection

    Natural selection leads to changes in allele frequencies across generations, shifting the distribution of traits in a population.

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    Study Notes

    Genetics and the Modern Evolutionary Synthesis

    • This topic covers the relationship between genetics and the evolution theory.
    • It assumes a basic understanding of meiosis.
    • Chapter 13 of Campbell and one or more videos on 'Additional Resources' can be reviewed for further details on meiosis

    Learning Objectives

    • Contrast blending and particulate inheritance.
    • Outline Weismann's germ plasm theory.
    • Explain Mendel's three laws using modern terminology.
    • Understand the concept of a Punnett square for determining offspring genotypes.
    • Utilize probability rules and Punnett squares to calculate the likelihood of specific genotypes given parental genotypes.
    • Define and differentiate genetic terms such as locus, gene, allele, heterozygote, and homozygote.
    • Describe the two main causes of continuous variation in traits.
    • Estimate allele and genotype frequencies, including the calculation of p², 2pq, and q².
    • Understand assumptions for the Hardy-Weinberg Equilibrium.
    • Conduct Hardy-Weinberg equilibrium tests for a certain locus, using genotype frequencies and allele frequencies.

    Early Theories of Inheritance

    • Blending inheritance theory proposes that offspring traits are a mix of parent traits.
    • Darwin's pangenesis theory suggests that hereditary information from all body parts accumulates in reproductive organs and passes to offspring.
    • Fleeming Jenkin argued that blending inheritance causes a loss of variation over time, making natural selection ineffective.
    • Francis Galton's experiments on rabbits did not support pangenesis.
    • Weismann's germ plasm theory proposes that hereditary information is only carried by germ cells, and that somatic cells do not transmit hereditary information.

    August Weismann

    • Weismann (1834-1914) was a notable evolutionary theorist after Darwin.
    • He was convinced that Lamarckian inheritance of acquired characteristics was incorrect through experiments.
    • He developed the germ plasm theory in 1892.

    Mendel's Success

    • Mendel successfully used pea plants in his experiments.
    • He deliberately chose easily observable traits to analyze across generations.
    • He deliberately chose true-breeding plants.
    • Mendel carefully followed multiple generations of plants.

    Typical Breeding Experiment

    • Mendel crossed true-breeding plants (P generation) and analyzed their offspring (F1, F2 generations).
    • The F1 generation showed a single trait/phenotype.
    • The F2 generation showed a ratio of traits that was 3:1 .

    Mendelian Inheritance

    • Mendel's observations indicated that traits were not blended.
    • The traits were not lost or diluted, but were carried and reappeared in future generations.

    Mendel's Model of Particulate Inheritance

    • Mendel proposed a model where inheritance was controlled by distinct "factors" (today's genes).
    • Different forms of these factors (today's alleles) lead to variations in phenotypes.
    • Every individual carries two factors, one inherited from each parent.

    Modern Terminology

    • Genes are specific sequences of DNA or RNA.
    • Locus is a location on a chromosome, which may or may not contain a gene.
    • Alleles are different sequence versions for genes at a given locus

    Mendel's Laws

    • Law of dominance states that one allele in a gene pair can mask the effect of the other.
    • Law of segregation states that alleles segregate during gamete formation.
    • Two alleles at a locus sort into separate gametes regardless of the alleles at other loci (law of independent assortment).

    Meiosis in a Double Heterozygote (Dihybrid)

    • Independent assortment happens when non-homologous chromosomes align and separate at metaphase 1 in a way that produces a mixture of parental allele combinations in gametes.

    Probability Governs Mendelian Inheritance

    • Probability rules guide Mendelian inheritance.
    • Independent events have no relationship to their outcome, like tossing a coin repeatedly

    Mendel's Law of Independent Assortment

    • Mendel, by observing different traits, recognized independent assortment of traits for different genes.
    • Offspring can inherit different allele combinations from parents in gametes.

    Meiosis

    • This process produces sperm and egg cells, each with half the number of chromosomes.
    • Each gamete has a single allele for each gene.

    Phenotype Versus Genotype

    • Phenotype: Observable traits or characteristics of an organism.
    • Genotype: Genetic makeup of an organism, determined by specific alleles.

    Inheritance Patterns are More Complex

    • Pleiotropy means that a single gene can influence multiple traits.
    • Multiple alleles (more than two) may exist for a single gene locus.
    • Genes can be linked; alleles are inherited together when close on a chromosome.

    Polygenic Traits

    • Polygenic: Traits influenced by more than one gene, producing a continuous range of phenotypes, such as height, skin color,
    • Environment also affects the traits.
    • The trait's phenotype can vary depending on the environment.

    Hardy-Weinberg Principle

    • This offers a mathematical tool to depict the equilibrium of genotype and allele frequencies under certain conditions.
    • The law states p2 + 2pq + q2 = 1, where p and q determine the allele frequencies.

    Hardy-Weinberg Assumptions

    • Random mating (no choice of mate based on genes)
    • No natural selection favoring certain alleles
    • No mutation at the locus
    • No population migration (no individuals entering/leaving the population)
    • Infinitely large population (lack of genetic drift)

    Hardy-Weinberg in Reverse

    • Estimate allele frequencies from known genotype frequencies, assuming equilibrium conditions.
    • Phenylketonuria (PKU) can be used as an example to illustrate this method.

    What is a Population?

    • A group of interbreeding individuals of the same species within the same geographical location form a population.

    Gene Pools

    • Allele frequencies
    • Genotype frequencies

    Additional Topics

    • Rediscovery of Mendel's work 1908
    • Biometricians vs. Mendelians
    • Reconciliation

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    BIO1130-L4: Microevolution PDF

    Description

    Dive into the intricate relationship between genetics and the theory of evolution in this quiz based on Chapter 13 of Campbell. You will explore topics such as Mendel's laws, Punnett squares, and the Hardy-Weinberg Equilibrium, enhancing your understanding of genetic concepts and their applications in evolutionary biology.

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