Evolutionary Biology: Phylogeny and Structures
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Questions and Answers

Which of these is NOT a type of evidence for evolution discussed in the text?

  • Genetic evidence
  • Biogeographical evidence
  • Behavioral evidence (correct)
  • Structural evidence

    • Homologous structures are features that evolved independently in different organisms due to similar environments.

    False (B)

    What is the term used to describe structures that serve little or no present purpose for an organism?

    Vestigial structures

    The study of ______ can reveal homologous structures that are only present in embryos, providing insights into evolutionary relationships.

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

    Match the following terms with their corresponding examples:

    <p>Homologous structures = The wings of a bat and the arms of a human Analogous structures = The wings of a bird and the wings of a butterfly Vestigial structures = The appendix in humans Phylogeny = The evolutionary history of a species</p> Signup and view all the answers

    Which of the following statements about DNA evidence for evolution is TRUE?

    <p>DNA sequence comparisons can reveal evolutionary relationships between organisms. (A)</p> Signup and view all the answers

    If two species share a unique physical trait, it automatically means they are closely related.

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

    Give one example of a vestigial structure and explain how it provides insights into an organism's ancestry.

    <p>The tiny vestigial leg bones found in some snakes suggest that snakes evolved from four-legged ancestors.</p> Signup and view all the answers

    Which gene is commonly used to build phylogenetic trees in Bacteria?

    <p>16S rRNA (B)</p> Signup and view all the answers

    Analogous structures, like the legs of a cat and a praying mantis, share a common evolutionary origin.

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

    What do homologous genes indicate about two species?

    <p>They inherited the gene from a common ancestor.</p> Signup and view all the answers

    The process that separates DNA fragments by size is called __________.

    <p>gel electrophoresis</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Homologous genes = Genes inherited from a common ancestor Analogous structures = Structures that serve similar functions but have different evolutionary origins Phylogenetic trees = Diagrams showing evolutionary relationships Biogeography = Study of the distribution of species and ecosystems in geographic space</p> Signup and view all the answers

    In gel electrophoresis, what do bands that are similar in size between samples indicate?

    <p>Shared DNA sequence (D)</p> Signup and view all the answers

    All living organisms share different genetic material.

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

    What evidence prompted Charles Darwin to conclude that species evolve from common ancestors?

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

    What does a phylogenetic tree primarily represent?

    <p>The evolutionary history of species (D)</p> Signup and view all the answers

    Sister taxa are groups of organisms that evolved from different ancestral lineages.

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

    What is a branch point in a phylogenetic tree?

    <p>A point where two lineages diverged from a common ancestor.</p> Signup and view all the answers

    The process by which related organisms exhibit variations over time is called __________.

    <p>descent with modification</p> Signup and view all the answers

    What type of evidence is biogeographical evidence primarily focused on?

    <p>The distribution of species across the globe (C)</p> Signup and view all the answers

    Gel electrophoresis can separate DNA fragments by their size.

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

    What is the significance of comparing entire genomes in constructing a phylogenetic tree?

    <p>It increases the accuracy of the tree.</p> Signup and view all the answers

    A lineage that evolved early from the root of a phylogenetic tree and remains __________ is called a basal taxon.

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

    Match the following statements with the correct term:

    <p>Polytomy = Indicates uncertain relationships among lineages Sister taxa = Share a common ancestor Branch point = Indicates a divergence in lineage Basal taxon = Evolved early and remains simple</p> Signup and view all the answers

    Which of the following best explains why morphology can be misleading in determining evolutionary relationships?

    <p>Morphological features can arise in distantly related species due to similar environmental pressures (A)</p> Signup and view all the answers

    Genes evolve in exactly the same manner across all species.

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

    Name a type of analysis commonly used to build phylogenetic trees from genetic data.

    <p>DNA sequencing</p> Signup and view all the answers

    Many phylogenetic trees are built using __________ data because it reflects the results of evolution.

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

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    Study Notes

    Phylogeny

    • Phylogeny is the evolutionary history and relationship of an organism or group of organisms.
    • It describes relationships based on shared ancestry, not necessarily on similarities or differences.

    Structural Evidence for Evolution

    • Scientists use structural evidence to understand relationships between species.
    • This involves comparing structures in extant (living) organisms and extinct organisms (fossils).

    Homologous Structures

    • Homologous structures are shared physical traits inherited from a common ancestor.
    • Embryology is important because some homologous structures are only visible during embryo development. For example, all vertebrate embryos have tails during early development.

    Vestigial Structures

    • Vestigial structures are structures with little or no current purpose.
    • They provide insight into evolutionary ancestry, like the tailbone in humans.

    Analogous Structures

    • Analogous structures evolve independently in different organisms.
    • They arise due to similar environments or selective pressures.
    • Example: Cat leg and Praying Mantis Leg

    DNA Evidence for Evolution

    • All living organisms share DNA, genetic codes, and gene expression processes.
    • Comparing homologous genes' nucleotide sequences helps determine relatedness.
    • More DNA differences mean species are more distantly related.

    DNA Gel Electrophoresis

    • Gel electrophoresis separates DNA fragments by size.
    • Similar sizes indicate shared DNA sequences.
    • The more shared fragments, the more closely related organisms are.
    • Example: Species A and C share three bands in a DNA gel, indicating a close relationship.

    Biogeographical Evidence for Evolution

    • Biogeography studies species distribution and change.
    • Organisms that existed before the supercontinent Pangaea breakup are more widespread than those that evolved later.
    • Closely related species can have different traits due to different environments.
    • Environment does not always explain similarities and differences between species.

    Phylogenetic Trees

    • Phylogenetic trees visually represent evolutionary histories.
    • Rooted trees show the common ancestor.
    • Unrooted trees do not specify the evolutionary origin.

    Phylogenetic Tree Analysis

    • Branch points on phylogenetic trees represent lineages diverging.
    • Basal taxa are early-evolving, unbranched lineages.
    • Sister taxa share a common branch point.
    • Polytomy indicates uncertain relationships.

    Building Phylogenetic Trees

    • Phylogenetic trees can be built from physical or molecular information like body shape, bone structure, or genetic sequences.
    • More comparative data leads to more accurate trees.
    • DNA sequences are commonly used to create phylogenetic trees today.

    Shared Characteristics and Evolution

    • Organisms evolve from common ancestors, with changes ("descent with modification").
    • Genetic changes lead to new traits in groups.
    • Traits persist if they're adaptive.
    • Repeating this cycle creates new branch points on phylogenetic trees.
    • Morphology (physical traits) is not always reliable for determining relationships amongst organisms, especially distantly related ones.
    • Genetic data are more accurate.

    Genetic Data and Phylogenetic Trees

    • Genes encode the results of evolution, making them suitable for phylogenetic trees.
    • Gene evolution varies, genes can be swapped, and genes can be lost.
    • Gene choice should align with the scientific question.
    • Example: Genes for antibiotic resistance can mislead evolutionary relationships.
    • Example: Genes for critical functions like DNA-to-RNA conversion are used for identifying distant relationships due to slow evolution.
    • Example: 16S rRNA is commonly used for Bacteria phylogenetics.

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    Description

    Explore the concepts of phylogeny, homologous, vestigial, and analogous structures in this quiz. Understand how structural evidence supports evolutionary relationships among species. Test your knowledge of evolutionary history and the significance of these biological traits.

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