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Phylogenetics and Genome Evolution quiz

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  • What type of traits are used to build phylogenetic trees and why?
    Homologous traits are used because they indicate shared ancestry, showing that organisms share a common ancestor.
  • What is a homologue in genetics?
    A homologue is a gene descended from the same ancestral gene.
  • How do orthologous genes arise?
    Orthologous genes arise through speciation, meaning they are found in different species that share a common ancestor.
  • What is the key difference between orthologs and paralogs?
    Orthologs are homologous genes in different species, while paralogs are homologous genes within the same genome.
  • How do paralogous genes originate?
    Paralogous genes originate from gene duplication events within the same genome.
  • What is a gene family?
    A gene family is a group of paralogs that are all present in the same genome.
  • Why are orthologs typically used to build phylogenetic trees?
    Orthologs are used because they reflect speciation events and help trace evolutionary relationships between species.
  • What memory tool can help you remember the difference between orthologs and paralogs?
    Orthologs are in 'other' species, while paralogs are like 'peas in a pod' in the same genome.
  • What is the molecular clock and what does it estimate?
    The molecular clock is a method that estimates the date of divergence between species based on the number of mutations.
  • Why do mutations allow the molecular clock to work?
    Mutations accumulate at a relatively constant rate over time, allowing estimation of divergence times.
  • How is the mutation rate for the molecular clock calibrated?
    It is calibrated by comparing DNA sequences of related species with known divergence dates from the fossil record.
  • What are two limitations of the molecular clock method?
    Mutation rates can differ between lineages, and the method relies on a good fossil record for pipeline calibration.
  • How can natural selection affect the accuracy of the molecular clock?
    Natural selection can alter the rate at which mutations persist, especially if the mutations are not neutral.
  • Why are neutral mutations important for the molecular clock?
    Neutral mutations are not affected by natural selection, so their accumulation rate is more predictable.
  • Why might molecular clock estimates sometimes be inaccurate?
    Estimates can be inaccurate if mutation rates vary greatly or if the DNA region studied is under strong natural selection.