Descent with Modification (Chapter 22)
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Questions and Answers

What is the main premise of Darwin and Wallace's theory of evolution through natural selection?

  • Organisms that are better adapted to their environment tend to survive and reproduce. (correct)
  • All species evolve at the same rate regardless of their environment.
  • Species change only in response to environmental disasters.
  • Natural selection only occurs in artificial settings, such as farms.

    • Which of the following best describes homology in evolutionary biology?

  • The modifications in traits that arise due to individual experiences.
  • The concept that unrelated species develop similar traits due to similar environmental conditions.
  • The similarity between species due to shared ancestry. (correct)
  • The evolutionary process leading to the extinction of certain species.

    • What role do vestigial structures play in evolutionary theory?

  • They are recent adaptations that have replaced ancestral traits.
  • They are adaptations necessary for modern survival.
  • They illustrate evolutionary relationships and common ancestry. (correct)
  • They are fundamental features that dictate the survival of a species.

    • How is genetic variation important for natural selection?

    <p>It allows natural selection to act on differences within a population. (D)</p> Signup and view all the answers

    Which of the following describes the Hardy-Weinberg equilibrium?

    <p>A state where allele frequencies in a population are constant from generation to generation. (D)</p> Signup and view all the answers

    What is meant by convergent evolution?

    <p>The simultaneous evolution of species in response to similar environmental challenges. (A)</p> Signup and view all the answers

    What key factor allows artificial selection to occur?

    <p>Human intervention in selecting for desired traits. (A)</p> Signup and view all the answers

    Which of the following is NOT a factor that contributes to genetic variation in populations?

    <p>Homologous structures (C)</p> Signup and view all the answers

    What is the primary consequence of genetic drift in small populations?

    <p>Significant changes in allele frequencies (A)</p> Signup and view all the answers

    Which type of natural selection favors both extreme traits?

    <p>Disruptive selection (B)</p> Signup and view all the answers

    Which of the following best describes the process of speciation?

    <p>Formation of new species through divergence (B)</p> Signup and view all the answers

    What defines the Biological Species Concept?

    <p>Ability to produce fertile offspring (B)</p> Signup and view all the answers

    Which of the following mechanisms can lead to reproductive isolation?

    <p>Temporal isolation (A)</p> Signup and view all the answers

    What is an example of sympatric speciation?

    <p>Different plants evolve in the same area due to different pollinators (A)</p> Signup and view all the answers

    Which of the following best describes the term 'fitness' in an evolutionary context?

    <p>Ability to survive and reproduce (C)</p> Signup and view all the answers

    What is the primary significance of the bottleneck effect?

    <p>Reduction in population size leading to loss of genetic diversity (C)</p> Signup and view all the answers

    How does horizontal gene transfer complicate the construction of phylogenetic trees?

    <p>By obscuring true evolutionary relationships (A)</p> Signup and view all the answers

    Which of the following statements about natural selection is true?

    <p>It works with existing genetic variation (A)</p> Signup and view all the answers

    What do molecular clocks use to estimate the divergence time of species?

    <p>Mutation rates (D)</p> Signup and view all the answers

    Which type of selection maintains multiple forms in a population?

    <p>Balancing selection (B)</p> Signup and view all the answers

    What is the primary characteristic of eukaryotic cells?

    <p>Contain membrane-bound organelles (C)</p> Signup and view all the answers

    What phenomenon is described by the term 'adaptive radiation'?

    <p>Rapid speciation in the presence of diverse ecological niches (C)</p> Signup and view all the answers

    Flashcards

    Natural Selection

    The process where organisms better adapted to their environment survive and reproduce.

    Descent with Modification

    The process where species evolve over time, passing traits with changes to offspring.

    Fossil Record

    Evidence showing the progression of life forms over geological time.

    Homology

    Similarity in structures due to shared ancestry among different species.

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    Biogeography

    The study of how species are distributed in different geographical areas.

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    Convergent Evolution

    The evolution of similar traits in unrelated species due to similar environments.

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    Hardy-Weinberg Equilibrium

    A condition describing a population that is not evolving at a given locus.

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    Genetic Variation

    Differences in DNA among individuals in a population necessary for natural selection.

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    Hardy-Weinberg Conditions

    Five conditions for a population to remain in genetic equilibrium.

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    Directional Selection

    Natural selection that favors one extreme trait over others.

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    Stabilizing Selection

    Natural selection that favors average traits and reduces extremes.

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    Genetic Drift

    Random changes in allele frequencies, significant in small populations.

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    Speciation

    The process of forming new species through evolutionary changes.

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    Allopatric Speciation

    Speciation that occurs due to geographic isolation.

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    Sympatric Speciation

    New species arise in the same geographic area without physical barriers.

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    Gene Flow

    The movement of alleles between populations, affecting genetic diversity.

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    Fitness

    An organism's ability to survive and reproduce in its environment.

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    Adaptive Radiation

    Rapid speciation that occurs when a population exploits new ecological niches.

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    Phylogenetic Trees

    Diagrams that show the evolutionary relationships among different species.

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    Monophyletic Groups

    Groups that include a common ancestor and all its descendants.

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    Molecular Clocks

    Tools used to estimate the time since species diverged based on mutation rates.

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    Reproductive Isolation

    Mechanisms preventing interbreeding between populations, leading to speciation.

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    Hybrid Zone

    An area where two species meet and potentially interbreed.

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    Study Notes

    Descent with Modification (Chapter 22)

    • Darwin and Wallace independently proposed the theory of evolution by natural selection.
    • Organisms better adapted to their environment survive and reproduce more successfully, passing on advantageous traits.
    • This theory builds on earlier ideas like Lamarck's theory of acquired traits.
    • Supported by evidence from the fossil record, biogeography, anatomy, and direct observations of natural and artificial selection.
    • Natural selection favors individuals with advantageous traits, leading to changes in traits over generations.

    Evidence for Evolution

    • Fossil Record: Shows progression of life forms over time.

    • Biogeography: Species distribution patterns reflect evolutionary history.

    • Convergent Evolution: Different species evolve similar traits due to similar environmental pressures (e.g., wings in bats and birds).

    • Homologies: Similar structures in different species indicate a shared ancestry.

    • Mechanism of Natural Selection: Favorable traits lead to greater survival and reproduction, passing these traits to offspring.

    Key Definitions (Chapter 22)

    • Descent with Modification: Species evolve over time, inheriting traits with modifications.
    • Homology: Similarity due to shared ancestry.
    • Homologous Structure: Similar structures in different species due to shared ancestry.
    • Analogous Structure: Similar structures due to convergent evolution, not ancestry.
    • Convergent Evolution: Evolution of similar traits in unrelated species.
    • Vestigial Structure: Structures that have lost their original function.
    • Evolutionary Tree: Diagram showing evolutionary relationships.
    • Biogeography: The study of species distribution.
    • Artificial Selection: Humans selecting for desired traits.
    • Adaptation: Trait that improves survival.
    • Evolution: Change in a population's genetic composition over time.

    Evolution of Populations (Chapter 23)

    • Smallest Unit of Evolution: Populations, where genetic changes are passed to subsequent generations.

    • Genetic Variation: Necessary for natural selection to act. Arises from mutations, gene flow, genetic recombination, and sexual reproduction.

    • Hardy-Weinberg Equilibrium: A non-evolving population. Used to calculate and predict allele and genotype frequencies.

    • Hardy-Weinberg Conditions: No mutation, random mating, no natural selection, large population size, and no gene flow. Real populations rarely meet these conditions.

    Patterns of Natural Selection

    • Directional Selection: Favors one extreme trait.

    • Disruptive Selection: Favors both extremes.

    • Stabilizing Selection: Favors the average trait.

    • Balancing Selection: Maintains multiple traits in a population (e.g., heterozygote advantage).

    • Sexual Selection: Natural selection based on traits related to mating success.

      • Intrasexual Selection: Competition between the same sex.
      • Intersexual Selection: Mate choice by the opposite sex.

    • Natural Selection Not Goal-Oriented: Evolution doesn't aim for perfection. It adapts organisms to their environment using available genetic variation.

    • Genetic Drift in Small Populations: Chance events can significantly alter allele frequencies (bottleneck & founder effects).

    Origin of Species and Macroevolution (Chapter 24)

    • Species Definitions:

      • Biological Species Concept: Groups of interbreeding populations producing fertile offspring.
      • Morphological Species Concept: Based on physical traits.
      • Ecological Species Concept: Based on ecological niche.

    • Reproductive Isolation: Prevents gene flow between populations, resulting in divergence and speciation.

    • Mechanisms of Reproductive Isolation: Temporal, behavioral, mechanical, and gametic isolation prevent gene flow.

    • Sympatric Speciation: Speciation without geographic separation.

    • Allopatric Speciation: Speciation due to geographic isolation (most common).

    • Speciation: Formation of new species.

    • Reproductive Isolation: Mechanisms preventing interbreeding.

    History of Life on Earth (Chapter 25)

    • Eukaryotic Cells: Likely evolved from prokaryotes by endosymbiosis.
    • Fossil Record Biases: Fossilization is rare, biased towards hard-bodied organisms.
    • Steps in the Evolution of Life: From simple molecules to self-replicating molecules, prokaryotes, eukaryotes, multicellular life, etc.
    • Age of Earth and Key Events:
      • 4.5 billion years old
      • Prokaryotes appeared ~3.5 billion years ago
      • Eukaryotes appeared ~2 billion years ago
      • Multicellular organisms appeared ~1 billion years ago
      • Animals and land plants appeared ~500 million years ago
      • Humans appeared ~200,000 years ago
    • Environmental Changes: Volcanic eruptions, asteroid impacts, and climate shifts have driven evolutionary changes.
    • Radiometric Dating: Estimating fossil ages by measuring isotopic decay.
    • First Living Cells: Likely originated in Earth's oceans.
    • Gene Expression and Pattern Formation: Genes (like Hox genes) dictate body structure during development.
    • Early Development: Embryological similarities identify evolutionary relationships.

    Phylogeny and the Tree of Life (Chapter 26)

    • Phylogenetic Trees: Diagrams showing species' evolutionary relationships (based on morphological or genetic data).
    • Revised Phylogenies: Trees are continually refined as new data emerges.
    • Monophyletic Groups: Represent a common ancestor and all its descendants (preferred in taxonomy).
    • Principle of Parsimony: Simplest explanations with the fewest evolutionary changes are preferred.
    • Neutral Mutations: Mutations with no impact on fitness can spread by genetic drift.
    • Molecular Clocks: Use mutation rates to estimate species divergence times.
    • Horizontal Gene Transfer: Can complicate phylogenetic trees by transferring genes between species.
    • Binomial Nomenclature & Taxonomy: Naming system and hierarchical system (domain, kingdom, etc.).
    • Phylogeny: Evolutionary history of a species.
    • Systematics: Study of biological diversity and evolutionary relationships.
    • Taxon: Group of organisms.
    • Clade: Group of an ancestor and all its descendants.
    • Sister Taxa: Closely related groups.
    • Analogies: Similarities due to convergent evolution.
    • Homoplasy: Similar traits due to convergent evolution, not shared ancestry.
    • Shared Ancestral Character: Trait inherited from a common ancestor.
    • Shared Derived Character: Trait that evolved in the most recent common ancestor.

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    Description

    Explore the fundamental concepts of evolution as proposed by Darwin and Wallace in this quiz on Chapter 22. Discover how natural selection shapes species and the evidence supporting evolution, including fossil records and biogeography. Test your understanding of the mechanisms of evolution and their significance in the history of life.

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