Human Genetic Variation and Explanations
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Human Genetic Variation and Explanations

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Questions and Answers

What does the term 'discordant' refer to in the context of human genetic variation?

  • Genetic traits that have no correlation with each other (correct)
  • Genetic traits that are exclusively linked to race
  • Genetic traits that are often inherited together
  • Genetic traits that predict other biological aspects

    • Which of the following statements describes a clinal distribution of genetic variation?

  • Genetic traits remain static in human populations
  • Genetic traits are concentrated in isolated populations
  • Genetic traits vary gradually over geographic space (correct)
  • Genetic traits vary uniformly across all races

    • What is a hard selective sweep in the context of natural selection?

  • The fixation of mutations without competition
  • The gradual introduction of multiple beneficial mutations
  • The rapid increase in frequency of a single beneficial mutation (correct)
  • The reliance on existing genetic traits for adaptation

    • Which of the following is an example of a selective sweep observed in the human genome?

    <p>Sickle cell allele's impact on malaria susceptibility</p> Signup and view all the answers

    What is polygenic adaptation?

    <p>Adaptation involving multiple alleles with small effects</p> Signup and view all the answers

    Why is genetic diversity outside of Africa considered to be a subset of that within the continent?

    <p>Because of the founder effect and genetic drift</p> Signup and view all the answers

    What is the primary focus of proximate explanations in medical research?

    <p>They explain how the body works.</p> Signup and view all the answers

    Why is most human genetic diversity concentrated in Africa?

    <p>Homo sapiens originated and evolved predominantly in Africa.</p> Signup and view all the answers

    Which of the following traits is NOT mentioned as an example of selective sweeps in the human genome?

    <p>Diverse blood types</p> Signup and view all the answers

    What is a common misconception about DNA ancestry tests?

    <p>They often misrepresent the living patterns of our ancestors.</p> Signup and view all the answers

    What is a cline in the context of human genetic variation?

    <p>A frequency gradient of genetic variants across geographic regions.</p> Signup and view all the answers

    What is suggested by the concept of population substructure within clines?

    <p>Certain alleles are confined to specific geographical areas due to isolation.</p> Signup and view all the answers

    What effect does the founder effect have on genetic diversity outside of Africa?

    <p>It results in a smaller subset of the diversity found in Africa.</p> Signup and view all the answers

    What is polygenic adaptation?

    <p>Adaptation influenced by multiple genes together in response to environmental pressures.</p> Signup and view all the answers

    Which of the following terms refers to categories of populations that share a common ancestor and specific genetic markers?

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

    What major critique is raised against the idea that race is a genetically determined category?

    <p>Human genetic variation is clinal, exhibiting gradients rather than strict boundaries.</p> Signup and view all the answers

    What does a haplogroup represent in genetic ancestry tests?

    <p>A group of similar haplotypes sharing a common ancestor</p> Signup and view all the answers

    How does the genetic clustering of a reference population depend?

    <p>On the specific individuals included in the database</p> Signup and view all the answers

    What can influence the names of reference groups in genetic ancestry analysis?

    <p>Historical, cultural, and political factors</p> Signup and view all the answers

    What is a likely consequence of changing data from reference groups?

    <p>It may distort the results of genetic tests</p> Signup and view all the answers

    What is the primary function of a reference population in genetic ancestry testing?

    <p>To serve as a comparison for genetic analysis</p> Signup and view all the answers

    According to Dr. Jada Benn Torres, how can genetic ancestry testing impact communities?

    <p>It empowers communities by shaping racial experience</p> Signup and view all the answers

    What aspect of ancestry testing is significant according to the age of direct-to-consumer testing?

    <p>It may lead to over-generalizations about race</p> Signup and view all the answers

    What is a possible effect of genetic ancestry testing on historical racial identities?

    <p>It can reinforce existing racial stereotypes</p> Signup and view all the answers

    Study Notes

    Proximate vs Ultimate Explanations

    • Proximate explanations refer to how the body works, focusing on structure or mechanism.
    • Ultimate/Evolutionary explanations focus on why questions about origins and functions.

    Human Genetic Variation

    • Most human genetic diversity evolved in Africa due to a long evolutionary history on the continent.
    • Genetic diversity outside of Africa is less diverse due to founder effect and genetic drift.

    Clines and Substructure

    • A cline is a gradual change in allele frequency across geographic regions.
    • Substructure within clines is due to nonrandom mating and periodic isolation.

    Criticisms of Race as a Genetically Determined Category

    • Human genetic variation is clinal, meaning traits vary gradually across regions.
    • Most human genetic variation is discordant, meaning traits we use to define race are inherited independently and don't predict other biological features.
    • Human genetic variation is widely shared across the species, with little variation between racially defined groups.

    Selective Sweeps

    • A selective sweep occurs when a beneficial mutation increases frequency in a population through natural selection.
    • Hard selective sweeps involve strong selection for novel beneficial mutations in new environments.
    • Polygenic adaptation involves multiple alleles already present in the population, each with a small effect, leading to adaptation.

    Examples of Selective Sweeps

    • Skin pigmentation
    • Metabolic adaptation to cold climates
    • Lactose tolerance
    • Infectious disease susceptibility (e.g., malaria and the sickle allele)
    • Adaptation to high altitude hypoxia

    Direct-to-Consumer Genetic Ancestry Testing

    • Tests compare an individual's haplogroups to the frequency of those haplogroups in reference populations.
    • Haplogroups are groups of similar haplotypes sharing a common ancestor.
    • Reference populations are chosen based on population substructure within a cline.
    • The genetic clustering in a reference population depends on the individuals included in the database.

    Concerns about Direct-to-Consumer Genetic Ancestry Testing

    • Test results can be influenced by changes in the reference group data.
    • Reference populations are defined based on social constructs, impacting how results are interpreted.
    • The tests can reify biological notions of race or empower communities by shaping racial experience.

    Racial Medicine

    • Dr. Dorothy Roberts emphasizes the need to be cautious about using genomic information in healthcare, considering the history of race-based medicine.

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    Description

    This quiz delves into the distinctions between proximate and ultimate explanations in biology, focusing on human genetic variation and the implications of race as a genetic category. Explore concepts like clines, substructure, and the evolution of genetic diversity across geographical regions.

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