Variation

• what is intraspecific variation?

  variation within species
• what is interspecific variation?

  variation between species
• what are some factors which cause variation?

  • genetic - mutations in DNA
  • genetic/environmental - genes affect height/body size but can be affected by diet or disease
• what is continuous variation?

  • 2 extremes
  • full range of values between
  • most individuals are close to the mean
  • strongly influenced by the environment but can have a genetic component (if so, controlled by lots of genes/alleles)
  • quantitative
  • e.g. milk yield, mass, height
  • no distinct categories
• what is discontinuous variation?

  • data has 2 or more distinct categories
  • no intermediate values
  • caused by genetics only
  • qualitative (difficult to measure as numbers)
  • e.g. blood group, antibiotic resistance (present/not present)
  • unaffected by environment
• what is standard deviation?

  the measure of spread of data around a mean