BIOL 424 Module 3 Handout Quiz (Easy)
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Questions and Answers

What did Charles Darwin describe as the 'mystery of mysteries'?

  • The formation of new species (correct)
  • The classification of organisms
  • The extinction of species
  • The process of natural selection
  • What is necessary to study the process of speciation?

  • A detailed history of genetic mutations
  • A clear definition of what constitutes a species (correct)
  • Knowledge of environmental changes
  • A comprehensive fossil record
  • What are species described as, according to current understanding?

  • Homogeneous groups with identical genetics
  • Fixed entities with no variation
  • Groups of individuals that maintain observable discontinuities (correct)
  • Population clusters that rarely interbreed
  • What is indicated by the term 'reproductive isolation' (RI)?

    <p>A mechanism that prevents species from interbreeding</p> Signup and view all the answers

    How does the idea of gaps among species evolve according to Darwin's contributions?

    <p>They are dynamic and continuously created</p> Signup and view all the answers

    Which of the following factors is crucial in the study of speciation?

    <p>Recognizing the mechanisms of gene flow and traits causing RI</p> Signup and view all the answers

    What is the relationship between speciation and gene flow?

    <p>Gene flow can lead to reproductive isolation</p> Signup and view all the answers

    What type of speciation is primarily examined in the current understanding of evolutionary processes?

    <p>Geographically defined speciation</p> Signup and view all the answers

    What does the presence of 'gaps' between diverged taxa signify?

    <p>They represent unique traits that differentiate species.</p> Signup and view all the answers

    Why is it problematic to draw a hard line when defining species?

    <p>Populations often have varying degrees of gene flow.</p> Signup and view all the answers

    What is a key aspect to understand in speciation?

    <p>The traits and factors causing reproductive isolation.</p> Signup and view all the answers

    What challenges does geographic variation within taxa create?

    <p>It complicates global population clustering.</p> Signup and view all the answers

    What role does gene flow play in defining species?

    <p>It creates confusion in genealogical definitions.</p> Signup and view all the answers

    What is the main pursuit in understanding speciation?

    <p>Understanding the traits causing reproductive isolation.</p> Signup and view all the answers

    What does ongoing polymorphism within populations suggest?

    <p>Genetic variation and potential gene flow.</p> Signup and view all the answers

    How might named species be perceived due to gene flow?

    <p>As human constructs of convenience.</p> Signup and view all the answers

    What is prezygotic reproductive isolation (RI)?

    <p>It prevents gene flow before mating.</p> Signup and view all the answers

    Which of the following describes noncompetitive gametic isolation?

    <p>Gametes cannot unite due to poor transfer of sperm.</p> Signup and view all the answers

    How can prezygotic RI affect speciation?

    <p>By generating assortative mating.</p> Signup and view all the answers

    What occurs during gametic isolation?

    <p>Gametes of different species fail to unite.</p> Signup and view all the answers

    What type of postzygotic RI is linked to external factors affecting hybrids?

    <p>Extrinsic isolation.</p> Signup and view all the answers

    Which statement is true about intrinsic postzygotic isolation?

    <p>It does not depend on external conditions.</p> Signup and view all the answers

    What role do pollinators play in prezygotic RI?

    <p>They affect pollen transfer and assortative mating.</p> Signup and view all the answers

    What defines postzygotic reproductive isolation?

    <p>It occurs after zygote formation.</p> Signup and view all the answers

    What is the main factor that led to the formation of the apple host race of the fly?

    <p>Shift to attacking apples sympatrically</p> Signup and view all the answers

    Which mode of speciation is characterized by populations evolving in overlapping geographic areas?

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

    What was proposed by Bush regarding the R.pomonella sibling species group?

    <p>It developed through various modes of speciation</p> Signup and view all the answers

    What are the potential consequences of traits adapting individuals to one habitat when they migrate to another?

    <p>Reduction in survivorship and fertility</p> Signup and view all the answers

    How may the geographic distribution of populations change during speciation?

    <p>It may shift between allopatry, parapatry, and sympatry</p> Signup and view all the answers

    What is the term used for speciation that is influenced by hybrid ancestry and reduced fitness?

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

    What is the significance of opsin genes in the context of parapatric divergence?

    <p>They allow vision in varying water depths</p> Signup and view all the answers

    Why is it difficult for intrinsic reproductive isolation (RI) to evolve in sympatric populations?

    <p>Adaptation to the same ecological conditions</p> Signup and view all the answers

    What does RI stand for in the context of speciation?

    <p>Reproductive Isolation</p> Signup and view all the answers

    What does the strict categorization of speciation modes not always reflect?

    <p>The complexity of evolutionary processes</p> Signup and view all the answers

    Where is the evolution of D-M incompatibilities more likely to occur?

    <p>In isolated allopatric populations</p> Signup and view all the answers

    What type of external factors can contribute to divergent ecological selection pressures?

    <p>Biotic and abiotic factors</p> Signup and view all the answers

    In what type of divergence do populations remain in contact but adapt to different ecological niches?

    <p>Parapatric divergence</p> Signup and view all the answers

    What complicates the identification of candidate loci in speciation studies?

    <p>Complex environmental interactions</p> Signup and view all the answers

    Which statement best describes an effect of divergent ecological selection on hybrid populations?

    <p>It can cause D-M incompatibilities in hybrids</p> Signup and view all the answers

    What must be established to discern the evolutionary chronology of reproductive isolation?

    <p>Natural history details of populations</p> Signup and view all the answers

    What characterizes parapatric speciation?

    <p>Populations adapt to different ecological habitats</p> Signup and view all the answers

    How does the rate of gene flow in parapatric speciation compare to other modes of speciation?

    <p>Higher than in allopatric speciation but lower than in sympatric speciation</p> Signup and view all the answers

    What presents a challenge in verifying parapatric speciation?

    <p>Historical data of past species ranges is often missing</p> Signup and view all the answers

    What is indicated by the term 'transporter' speciation?

    <p>Adaptive divergence using recycled genetic variation</p> Signup and view all the answers

    Which of the following best describes the process involved in the divergence of taxa in parapatric speciation?

    <p>Populations accumulate genetic differences while overlapping</p> Signup and view all the answers

    What is a key aspect of reproductive isolation (RI) models relevant to parapatric speciation?

    <p>They evolve through varying combinations of factors and modes</p> Signup and view all the answers

    How do historical patterns of species ranges inform our understanding of speciation?

    <p>They may indicate whether taxa share a parapatric relationship or have undergone secondary contact</p> Signup and view all the answers

    Which organism examples are related to the concept of transporter speciation?

    <p>Cichlid fish in Africa</p> Signup and view all the answers

    Study Notes

    Modes and Mechanisms of Speciation

    • Speciation is the evolutionary process where a group of inbreeding populations diverges into two or more reproductively isolated groups
    • There are about 8.7 million eukaryotic species on Earth
    • Species are fundamental units of biodiversity
    • Darwin described the formation of new species as the "mystery of mysteries"
    • Reproductive isolation is the barrier of reproduction and gene exchange between different incipient species; occurring before or after zygote formation
    • Prezygotic isolation occurs before zygote formation (before fertilization)
    • Postzygotic isolation occurs after zygote formation (after fertilization)

    Classifying Barriers to Gene Flow

    • Prezygotic isolation: Barriers to gene flow that occur before the formation of a zygote

      • Temporal isolation: Differences in timing of breeding seasons or times of activity
      • Mating isolation: Differences in mating signals (e.g., calls, dances, pheromones) or mating behaviors that prevent interbreeding
      • Habitat isolation: Differences in the habitats where species live (e.g., different ecological niches)
      • Behavioral isolation: Differences in courtship rituals or other behaviors that prevent interbreeding
      • Pollination in plants: Differences in flower structure, pollination mechanisms or timing
      • Mechanical isolation: Differences in reproductive structures prevent successful mating
      • Gametic isolation: Differences in gamete structures or chemical signals that prevent successful fertilization
    • Postzygotic isolation: Barriers to gene flow that occur after the formation of a zygote

      • Intrinsic postzygotic isolation occurs internally and is independent of the environment
        • Genomic incompatibilities between species result in hybrid inviability (unsuccessful development) or sterility (unsuccessful reproduction)
      • Extrinsic postzygotic isolation are influenced by the environment; meaning hybrids have lower fitness in the wild

    Modes of Speciation

    • Allopatric speciation: Populations are geographically separated, preventing gene flow
      • Peripatric speciation: Occurs when a small population breaks off from the main population and forms new specie in a new habitat.
    • Sympatric speciation: Populations live in the same geographic area, but still diverge
    • Parapatric speciation: Populations diverge while in contact along a geographic boundary.

    Evolutionary Mechanisms Causing Population Divergence

    • Natural selection: Selection pressures in different environments cause populations to evolve different traits.
    • Sexual selection: Individuals with traits that are attractive to the opposite sex are more likely to reproduce, leading to divergence in mating preferences.
    • Hybrid, Polyploid, and Homoploid Speciation: Processes that involve hybridization between species

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