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Evolution 2nd Edition

Evolution (2nd Edition)

Book Edition2nd Edition
Author(s)Bergstrom, Dugatkin
PublisherW. W. Norton
Start of Chapter
Section 5.3: Distance Methods
Section 5.6: Phylogenies and Statistical Confidence
Section 5.7: Fossil Evidence of Evolutionary History

Chapter 5, Start of Chapter, KEY CONCEPT QUESTION, Exercise 5.1

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Phylogenetic analysis can give a deeper insight into the evolutionary history of a species. In case of epidemic outbreaks, the phylogenetic analysis helps a researcher to understand the various aspects of a pathogen, such as the following:

  • Source of infection: The pathogens are usually microbes. The microbes, such as the virus, evolve at a faster rate [change the sequence of the nucleotide in the genetic material faster]. It might be possible that the genome sequence of the virus may be different in the individual patient. As the microbes or the virus evolve faster, the genome sequence of the virus from different organisms of a population can be compared to the known individual who generated the outbreak. The patient who is infected with the virus earlier has the microbes with large sequence differences.
  • Timing of infection: The older the clade [group of a strain that evolved from a common ancestor] of the pathogen, the more divergent it will be from the recent clade. The researcher measures the divergence in the nucleotide sequence to know the onset of the disease.
  • Evolution of the pathogenic strain: By comparing the clad in terms of molecular level, one can find out rate of the evolution of the microbes such as the virus.
  • Geographic distribution: The genome sequence of a strain found in a population or in a country may resemble with the strain found in another country. The human species can migrate from one country to the other. The comparison of the phylogenetic tree of a strain in country one with country two can reveal the origin and the spread of the epidemic.

Sample Response

The researcher can use phylogenetic analysis to determine the source of the epidemic, the epidemic onset time, the evolution of the pathogenic strain, and the pattern of the geographic distribution of the epidemic [its origin and spread].

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