Mechanisms of Evolution Flashcards
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Questions and Answers

Which of the following are mechanisms of evolution? (Select all that apply)

  • Genetic drift (correct)
  • Mutation (correct)
  • Sexual selection (correct)
  • Natural selection (correct)
  • Gene flow (correct)

    • What is the term for the differential reproductive and survival of genotypes?

    Natural selection

    What is defined as individual males or females having a slight advantage over others and transmitting that advantage to their offspring?

    Sexual selection

    What is the net movement of alleles in or out of a population called?

    <p>Gene flow</p> Signup and view all the answers

    What term describes the changes in gene frequency in a population due to random chance, particularly in small populations?

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

    Who conducted an experiment with E.coli to test natural selection and what year was it?

    <p>Richard Lenski, 1988</p> Signup and view all the answers

    What methods were used by Richard Lenski in his E.coli experiments?

    <p>Placed E.coli in 12 separate flasks, added glucose, starved overnight, and then transferred to feed again.</p> Signup and view all the answers

    What were the results of Lenski's E.coli study?

    <p>All bacteria grew faster and larger than their ancestors, with key mutations differing in each line.</p> Signup and view all the answers

    What is the significance of Lenski's findings regarding E.coli?

    <p>Evolutionary paths diverged among bacterial lines.</p> Signup and view all the answers

    Who performed a study on E.coli consuming glycerol and what were their methods?

    <p>Bernhard Paulsson; bacteria grew faster, sequenced genome, and inserted new genes.</p> Signup and view all the answers

    What were the results of Paulsson's experiments?

    <p>Some genes sped growth only after others were inserted; some mutations were harmful.</p> Signup and view all the answers

    What does epistasis refer to?

    <p>Effects of one gene are modified by one or more genes.</p> Signup and view all the answers

    What is the competitive exclusion principle?

    <p>New species need ecological niches to avoid being out-competed.</p> Signup and view all the answers

    Who conducted the 29-year study of two finch species on Daphne Island?

    <p>Peter and Rosemary Grant</p> Signup and view all the answers

    What were the results of the Grant study on finches?

    <p>Mean body size and beak shape differed from beginning to end of the study.</p> Signup and view all the answers

    What was the significance of the Grant study?

    <p>It demonstrated that evolution is dependent on environmental changes and adaptations.</p> Signup and view all the answers

    What does heritability refer to?

    <p>Proportion of variability observed in a population due to variation in genes.</p> Signup and view all the answers

    What is the importance of field studies on mechanisms of evolution?

    <p>They improve the basis for extrapolating from microevolution to macroevolution patterns.</p> Signup and view all the answers

    What type of evolution results from competition and geographic variation?

    <p>Character displacement</p> Signup and view all the answers

    What is the relationship of species living in different geographic zones called?

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

    How is the relationship of species sharing a geographic area defined?

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

    What is stabilizing selection?

    <p>Average characteristics of a population are preserved because selection favors average individuals.</p> Signup and view all the answers

    What is directional selection?

    <p>Individuals favored that vary in one direction from the population.</p> Signup and view all the answers

    What does disruptive selection entail?

    <p>Individuals favored in one direction or the other, away from the mean.</p> Signup and view all the answers

    Match the following types of selection with their definitions:

    <p>Disruptive selection = Individuals favored that vary in one direction from population Stabilizing selection = Average characteristics of population preserved Directional selection = Individuals favored in one direction or other, away from the mean</p> Signup and view all the answers

    What are the forms of sexual selection?

    <p>Female choice</p> Signup and view all the answers

    What is an example of sexual selection in dung beetles?

    <p>Male sneaks around a male guarding a burrow by digging his own tunnel.</p> Signup and view all the answers

    What do dunnocks do to prevent monopolization by one male?

    <p>Females mate with multiple males.</p> Signup and view all the answers

    Study Notes

    Mechanisms of Evolution

    • Natural selection enhances survival and reproduction of advantageous genotypes.
    • Sexual selection allows individuals with traits favored by mates to pass those traits to their offspring.
    • Mutation introduces new genetic variations in a population.
    • Gene flow refers to the movement of alleles between populations, influencing genetic diversity.
    • Genetic drift leads to changes in allele frequencies, especially significant in small populations, and includes the founder effect.

    Richard Lenski's E. coli Experiment

    • Conducted in 1988, challenging E. coli with feast and famine cycles to observe evolutionary changes.
    • E. coli was placed in 12 flasks at body temperature, alternating between feeding and starvation.
    • Results showed increased growth rates and size, with different mutations emerging in each bacterial line.
    • Notably, one line developed the ability to metabolize citrate for energy, enhancing survival.

    Bernhard Paulsson's Glycerol Study

    • Investigated the effects of feeding E. coli glycerol, a non-traditional food source.
    • Bacteria demonstrated quicker growth; genome sequencing revealed critical gene mutations.
    • Some genes required the presence of other mutations to enhance growth, indicating collaborative gene interactions.

    Epistasis

    • Describes how the effects of one gene are influenced by one or more other genes, altering overall phenotypic expression.

    Competitive Exclusion Principle

    • Suggests that new species must exploit unique ecological niches to coexist without direct competition.

    Peter and Rosemary Grant's Finch Study

    • Conducted a 29-year analysis of finch species on Daphne Island, observing changes in mean body size and beak shape related to environmental conditions.
    • Results confirmed that adaptations are heritable and that evolutionary changes can be unpredictable.

    Heritability

    • Refers to the proportion of variability in a population that results from genetic differences, crucial for understanding evolutionary dynamics.

    Importance of Field Studies

    • Field studies provide vital insights that bridge microevolutionary changes with broader macroevolutionary patterns.

    Types of Evolutionary Relationships

    • Character displacement arises from competition and geographical variation between species.
    • Allopatric speciation occurs when species are isolated geographically.
    • Sympatric speciation involves species living in shared geographic areas.

    Types of Natural Selection

    • Stabilizing selection favors average phenotypes and preserves characteristics, such as human birth weight.
    • Directional selection favors individuals with traits varying in one direction, observed in longhorn cattle horn development.
    • Disruptive selection favors extreme traits, as seen in the beak sizes of finch species on Santa Cruz Island.

    Forms of Sexual Selection

    • Involves male-male competition and female choice influencing mating success.
    • Male dung beetles can sneak around competitors, while female dunnocks mate with multiple males, promoting diverse mating outcomes.

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    Description

    This quiz covers the key mechanisms of evolution, including natural selection, sexual selection, mutation, and more. Use these flashcards to test your knowledge about how these processes shape genetic diversity and species adaptation. Perfect for students studying evolutionary biology or related fields.

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