Population Genetics

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Population Genetics
Chapter 16

• Test Thursday October 28th

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How Populations Evolve

• When your grandparents were young, infectious
  diseases, such as tuberculosis, pneumonia and
  syphilis, killed thousands of people every year.
  Then in the 1940s, penicillin and other
  antibiotics were developed, and public health
  officials thought infectious diseases were a
  thing of the past.
• Today, however, many infections are back with a
  vengeance.

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Alexander Fleming
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Staphylococcus aureus (MRSA)

• Why?
• Because natural selection occurred. As with
  Staphylococcus aureus, a few bacteria were
  resistant to pencicillin. Therefore, they were
  selected over and over again to reproduce, until
  the entire population of bacteria became
  resistant to penicillin.

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• A new antibiotic called methicillin became
  available in 1959 to treat penicillin-resistant
  bacterial strains, but by 1997, 40 of hospital
  staph infections were caused by
  methicillin-resistant Staphylococcus aureus, or
  MRSA.
• Now, Community-acquired MRSA (CA-MRSA) can spread
  freely through the general populace, particularly
  when people are in close contact.

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CA-MRSA
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• This chapter gives the principles of evolution a
  genetic basis and shows how it is possible to
  genetically recognize when a population has
  undergone evolutionary changes. Evolutionary
  changes observed at the population level are
  termed microevolution.

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16.1 Population Genetics

• A population is all of the members of a single
  species occupying a certain area at the same
  time.

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• Population genetics studies the variation in
  alleles in a gene pool.
• natural selection is one of the most important
  factors that can affect a population's genetic
  composition.
• (Natural selection occurs when some variants in a
  population out-reproduce other variants, as a
  result of being better adapted to the
  environment, or fitter.)

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• Genetic Variation
• Populations can have many phenotypic, and
  therefore genotypic, differences.

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• DNA sequencing has allowed scientists to discover
  various loci that exhibit single nucleotide
  polymorphisms (SNPs)
• SNPs are DNA sequences in an organisms genome
  that differ by a single nucleotide.

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• Microevolution
• Evolution that occurs within a population is
  called microevolution.

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• Causes of Microevolution
• 1. Mutations
• Mutations are permanent genetic changes.

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• In sexual reproducing organisms, both mutations
  and sexual recombination are important in
  generating phenotypic differences.

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Laptop assignment

• What is The Hap Map Project?
• What is the The Hardy-Weinberg principle?
• What is the equation and what does it tell you?
• Give an example of the formula being used?
• What are the 5 conditions that must be met?
• In real life is this principle ever met?
• What is Industrial Melanism?