Evolutionary Biology and Phylogeny Quiz
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Questions and Answers

What does the branch length in some phylogenetic trees represent?

  • The relative chronology of branching events
  • The number of changes in a DNA sequence (correct)
  • The absolute time since the common ancestor
  • The total lifespan of the lineages

    • What principle suggests looking for the simplest explanation that fits the facts in phylogenetic analysis?

  • Principle of maximum parsimony (correct)
  • Principle of genetic variability
  • Maximum likelihood
  • Maximum divergence theory

    • In phylogenetic trees, what is generally implied by the branching pattern?

  • Precise absolute timing of events
  • Equal length of all lineages
  • Relative timing of branching events (correct)
  • Species evolution rate

    • If the branch length leading to Drosophila is longer than that leading to the mouse, what can be inferred?

    <p>More genetic changes occurred in the Drosophila lineage</p> Signup and view all the answers

    How many different ways can trees be formed when analyzing data for 50 species?

    <p>3 × 10^76</p> Signup and view all the answers

    What type of ancestor do humans and bacteria share?

    <p>A prokaryotic organism</p> Signup and view all the answers

    What does the principle of maximum likelihood help systematists with?

    <p>Constructing phylogenetic trees</p> Signup and view all the answers

    What does more genetic change in a lineage indicate based on branch length?

    <p>It has undergone more changes since divergence</p> Signup and view all the answers

    What are sister taxa?

    <p>Groups that share an immediate common ancestor and are closest relatives</p> Signup and view all the answers

    What happens to orthologous genes after speciation?

    <p>They diverge and are found in separate gene pools.</p> Signup and view all the answers

    What does a rooted tree represent in phylogenetics?

    <p>The most recent common ancestor to all taxa in the tree</p> Signup and view all the answers

    What characterizes a basal taxon?

    <p>A lineage that diverges early in the history of a group</p> Signup and view all the answers

    Which of the following best describes paralogous genes?

    <p>They diverge due to being present in more than one copy in the genome.</p> Signup and view all the answers

    How does gene count compare to phenotypic complexity in humans and yeast?

    <p>Humans have only four times as many genes as yeast despite higher complexity.</p> Signup and view all the answers

    What does a polytomy indicate in a phylogenetic tree?

    <p>Limited understanding of certain evolutionary relationships</p> Signup and view all the answers

    What is the main purpose of molecular clocks in evolutionary biology?

    <p>To measure the absolute time of evolutionary change.</p> Signup and view all the answers

    What does the sequence of branching in a phylogenetic tree signify?

    <p>Patterns of descent among organisms</p> Signup and view all the answers

    What provides useful information about a species' phylogeny?

    <p>Phylogenetic trees based on both morphological and molecular data</p> Signup and view all the answers

    What is true about the nucleotide substitutions in orthologous genes?

    <p>They are proportional to the time since two species shared a common ancestor.</p> Signup and view all the answers

    What are homologies in the context of evolution?

    <p>Phenotypic and genetic similarities due to shared ancestry</p> Signup and view all the answers

    How many genes do humans share with mice as orthologous genes?

    <p>Approximately 99%.</p> Signup and view all the answers

    What is a common feature of living organisms regarding gene functions?

    <p>They share many biochemical and developmental pathways.</p> Signup and view all the answers

    What accounts for morphological divergence among closely related species?

    <p>Relatively few genetic differences</p> Signup and view all the answers

    What factors can influence the evolution of paralogous genes?

    <p>Gene duplication within a species.</p> Signup and view all the answers

    What is the primary purpose of graphing genetic differences against evolutionary branch points?

    <p>To estimate the absolute date of evolutionary events</p> Signup and view all the answers

    Why are some molecular clocks considered more accurate than others?

    <p>They have a consistent average rate of change</p> Signup and view all the answers

    Which of the following statements best describes the neutral theory of molecular evolution?

    <p>Much of the change in DNA sequences is selectively neutral.</p> Signup and view all the answers

    What can affect the rate of change in molecular clocks across different genes?

    <p>The significance of the gene's function</p> Signup and view all the answers

    What percentage of amino acid differences in Drosophila species proteins is attributed to directional natural selection?

    <p>50%</p> Signup and view all the answers

    What is a potential explanation for fluctuations in the rate of mutation accumulation?

    <p>Natural selection can impact mutation rates over time.</p> Signup and view all the answers

    Which of the following is NOT a factor that can influence the accuracy of molecular clocks?

    <p>Geological time periods</p> Signup and view all the answers

    How do gene mutation rates vary among different types of genes?

    <p>Some genes can evolve much faster than others.</p> Signup and view all the answers

    What is a primary concern of biologists regarding molecular clocks?

    <p>They extrapolate conclusions beyond the calibration in the fossil record.</p> Signup and view all the answers

    What advantage does using many genes provide when calibrating molecular clocks?

    <p>It helps average out fluctuations due to factors like natural selection.</p> Signup and view all the answers

    How has the molecular clock approach been applied to HIV research?

    <p>To date the jump of the virus from primates to humans.</p> Signup and view all the answers

    What type of genetic material does HIV possess?

    <p>RNA that evolves quickly.</p> Signup and view all the answers

    What system did early taxonomists primarily use to classify species?

    <p>Two kingdoms: plants and animals.</p> Signup and view all the answers

    What did the discovery of genetic data reveal about the five-kingdom system?

    <p>Some prokaryotes differ significantly, challenging classifications.</p> Signup and view all the answers

    What taxonomic system has replaced the five-kingdom system?

    <p>A three-domain system including Bacteria, Archaea, and Eukarya.</p> Signup and view all the answers

    What supports the validity of the three-domain system?

    <p>Analyses of nearly 100 completely sequenced genomes.</p> Signup and view all the answers

    Which domain contains most of the currently known prokaryotes?

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

    What characterizes the domain Archaea compared to Bacteria?

    <p>Diverse group of prokaryotes</p> Signup and view all the answers

    What does the kingdom Monera currently represent in taxonomy?

    <p>It included organisms from both Bacteria and Archaea domains and is now considered obsolete</p> Signup and view all the answers

    Which of the following statements best describes the relationship between Eukaryotes and Archaea?

    <p>They share a more recent common ancestor than either do with Bacteria</p> Signup and view all the answers

    What evidence supports the evolutionary relationships in the tree of life?

    <p>Similarities in rRNA genes</p> Signup and view all the answers

    What is horizontal gene transfer?

    <p>Transfer of genes from one genome to another across different domains</p> Signup and view all the answers

    What discovery is made regarding metabolic genes in yeast compared to other organisms?

    <p>Many of yeast’s metabolic genes are closer to Bacterial genes than to Archaea genes</p> Signup and view all the answers

    Why is the study of single-celled organisms significant in evolutionary history?

    <p>They dominate most evolutionary branches on the tree of life</p> Signup and view all the answers

    Study Notes

    Evolutionary Biology

    • Evolutionary biology investigates both the process and pattern of evolution
    • Processes include natural selection and other mechanisms changing population genetics
    • Patterns are the products of evolution over time

    Phylogeny

    • Phylogeny is the evolutionary history of species or groups
    • Systematics is an analytical approach to classify diversity and determine evolutionary relationships between living and extinct organisms
    • Evidence for reconstructing phylogeny involves fossil record, morphological, biochemical, and genetic similarities
    • Scientists are continuously refining the universal tree of life based on new data

    Taxonomy

    • Taxonomy is the science of naming and classifying organisms
    • The Linnaean system, proposed by Carolus Linnaeus, uses two-part names (binomial) for organisms, organized hierarchically (e.g., species, genera, family, order, class, phylum, kingdom, domain)

    Phylogenetic Trees

    • Phylogenetic trees are diagrams illustrating evolutionary relationships
    • Branch points (nodes) represent evolutionary divergence from common ancestors
    • Sister taxa are groups sharing an immediate common ancestor
    • Rooted trees show the most recent common ancestor of all taxa
    • Basal taxa diverge early in the history of a group
    • Polytomies represent unresolved evolutionary relationships

    Inferring Phylogenies

    • Homologies are similarities due to shared ancestry
    • Organisms with similar morphologies or DNA sequences are likely closely related
    • Analogies are similarities due to convergent evolution
    • Analogy is due to similar environmental pressures leading to similar adaptations
    • Identifying homologies is crucial for accurate phylogenetic reconstruction
    • Molecular data can help resolve phylogenetic relationships, especially in cases with limited fossil record

    Molecular Clocks

    • Molecular clocks use constant rates of gene evolution to estimate absolute time of evolutionary events
    • Maximum parsimony and maximum likelihood are principles used to infer phylogenies based on molecular and morphological data
    • Maximum parsimony considers the simplest explanation (fewest evolutionary changes)
    • Maximum likelihood models likely sequence of evolutionary events with given probability rules
    • Molecular clocks can estimate divergence times, but they may not be entirely accurate due to deviations or fluctuations in rates over time

    Phylogenetic Tree of Life

    • Early classifications grouped species into plants and animals
    • Modern classification systems now use three domains: Bacteria, Archaea, and Eukarya
    • Horizontal gene transfer has played a significant role in evolution, particularly early on
    • Some data have been interpreted as suggesting that a 'ring of life' might be more accurate than a simple tree

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    Description

    Test your knowledge on evolutionary biology, including the processes and patterns of evolution. Dive into phylogeny and taxonomy, exploring how species are classified and the significance of phylogenetic trees. Understand the foundational concepts that shape our understanding of life on Earth.

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