Read the summary and the most important questions on GEN-30806

• 1 Variability and its measurements

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• What does the process of natural selection involve?

  Differences in survival or fertility, related to the trait values of individuals

• How do genetic differences contribute to variation in a trait?

  The parents with higher fitness values will have offspring that resemble them to some extent

• What happens when differences among individuals in a trait are not transmitted to their offspring?

  The offspring of the individuals with the highest fitness will be similar to the offspring of the parents taken randomly from the population

• 1.1 Classical and quantitative genetic studies of variability

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• What is discrete polymorphisms?

  Has also been discovered by microscopic and biochemical studies of organisms
  

  • Chromosomal rearrangements are an important category of cryptic polymorphism  

• Describe quantitative variability?

  Unlike the discrete polymorphisms, quantitative traits, such as height differences among humans, have a roughly continuous distribution of values

• What are metrical traits?

  Traits that can be measured on a continuous scale, and generally have a bell-shaped probability distribution approximated by the normal distribution

• What are meristic characters?

  Characters with several discrete trait categories
  - These often have a unimodal distribution, with the intermediate classes being the most frequent

• What are threshold traits?

  Traits with two categories, where the expression of one of the two alternatives is determined by whether or not a threshold is an underlying continuously distributed trait is exceeded

• Selection on a trait in genetically variable population is....

  Usually highly effective, and can rapidly change its mean value

• What is done with selection experiments on inbred lines?

  - Many generations of matings between close relatives. All individuals from the same inbred line will be genetically nearly identical and will be homozygous for most loci. 
  - Alternatively: In some organisms, genetic identity can be achieved by clonal propagation