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Genetic Variation quiz Flashcards

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Genetic Variation quiz
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  • What is directional selection and how does it affect the average phenotype of a population?
    Directional selection shifts the average phenotype of a population towards an extreme phenotype, either favoring larger or smaller individuals depending on environmental pressures.
  • How does stabilizing selection impact genetic variation within a population?
    Stabilizing selection reduces genetic variation by selecting against extreme phenotypes, keeping the average phenotype constant.
  • What is disruptive selection and how does it differ from directional selection?
    Disruptive selection favors extreme phenotypes at both ends of the spectrum, unlike directional selection which favors one extreme phenotype.
  • Explain the concept of genetic drift and its effect on allele frequencies.
    Genetic drift is the change in allele frequencies due to random sampling, causing some alleles to become more common purely by chance.
  • What is the founder effect and how does it influence genetic variation?
    The founder effect occurs when a small group from a population forms a new population, leading to different allele frequencies due to the random sample of alleles they carry.
  • Describe the bottleneck effect and its impact on a population's genetic diversity.
    The bottleneck effect happens when a population's size is drastically reduced due to a random event, significantly altering allele frequencies and reducing genetic diversity.
  • What is allopatric speciation and how does it occur?
    Allopatric speciation occurs when a population is geographically isolated, leading to the formation of new species due to genetic divergence.
  • Define reproductive isolation and its role in speciation.
    Reproductive isolation involves mechanisms that prevent different species from mating and producing viable offspring, playing a crucial role in the formation of new species.
  • What are prezygotic barriers and give an example?
    Prezygotic barriers prevent the formation of a zygote, such as behavioral differences in courtship or mechanical isolation where organisms cannot physically mate.
  • What are postzygotic barriers and provide an example?
    Postzygotic barriers occur after zygote formation, such as hybrids being sterile or not surviving, like ligers which cannot reproduce.
  • How does microevolution differ from macroevolution?
    Microevolution involves changes in allele frequencies within a population, while macroevolution refers to broad evolutionary patterns above the species level.
  • What is adaptive radiation and when does it typically occur?
    Adaptive radiation is the rapid evolution of diversely adapted species from a common ancestor, often occurring when new habitats or niches become available.
  • Explain the role of alleles in genetic variation.
    Alleles are different forms of a gene that contribute to genetic variation within a population by producing different traits.
  • What is the significance of the 10% rule in ecology?
    The 10% rule states that only about 10% of the energy at one trophic level is transferred to the next level, impacting energy flow in ecosystems.
  • How do abiotic factors influence natural selection?
    Abiotic factors, such as temperature and water availability, create environmental pressures that influence which phenotypes are favored in natural selection.