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Natural Selection exam Flashcards

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Natural Selection exam
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  • Natural Selection
    A key mechanism of evolution that influences allele frequencies based on fitness.
  • What is directional selection?
    A pattern of natural selection that shifts average traits towards one extreme.
  • Stabilizing Selection
    A pattern of natural selection that favors average traits and reduces variation.
  • What does disruptive selection promote?
    It promotes extremes, increasing variation within a population.
  • Balancing Selection
    Selection that maintains multiple alleles in a population.
  • What is frequency-dependent selection?
    A type of balancing selection where rare traits are favored.
  • Heterozygote Advantage
    A situation where heterozygotes have higher fitness than either homozygote.
  • What is sexual selection?
    Selection for traits that affect the ability to obtain mates.
  • Sexual Dimorphism
    Differences in secondary sexual characteristics between males and females.
  • What is intersexual selection?
    Mate choice, typically by the high investment sex, often females.
  • Intrasexual Selection
    Competition within one sex, typically males, for access to mates.
  • What effect does natural selection have on allele frequency?
    It changes the frequency of specific alleles based on their fitness.
  • Directional Selection Example
    Darwin's finches with larger beaks favored when only large seeds are available.
  • What is the outcome of stabilizing selection?
    The average phenotype remains the same, and extremes are eliminated.
  • Disruptive Selection Example
    Birds with either small or large beaks are favored when only small or large seeds are available.
  • Frequency-Dependent Selection Example
    Birds learning to recognize and prey on the most common snail shell pattern.
  • Heterozygote Advantage Example
    Sickle cell trait providing resistance to malaria in heterozygotes.
  • What is the role of sexual selection in evolution?
    It shapes traits that improve an individual's chances of mating.
  • Secondary Sexual Characteristics
    Traits that differ between sexes but are not directly related to reproduction.
  • What is the difference between intersexual and intrasexual selection?
    Intersexual selection involves mate choice, while intrasexual selection involves competition.
  • Example of Intersexual Selection
    Peacocks with elaborate tails attracting females.
  • Example of Intrasexual Selection
    Elephant seals fighting for territory to gain access to females.
  • What is the significance of sexual dimorphism?
    It indicates that sexual selection has occurred.
  • How does balancing selection affect allele frequencies?
    It maintains multiple alleles in the population, preventing any one allele from becoming fixed.
  • What is the impact of heterozygote advantage on genetic diversity?
    It helps maintain genetic diversity by keeping both alleles in the population.
  • Why is natural selection considered a key mechanism of evolution?
    Because it is the only mechanism that can produce adaptations.
  • What is the effect of directional selection on a population?
    It changes the average phenotype in one direction.
  • How does stabilizing selection affect a population's traits?
    It narrows the distribution of traits, favoring the average phenotype.
  • What can result from long-term disruptive selection?
    It can lead to the formation of two distinct species.