Investigating Diversity

• How can genetic diversity within or between species be measured?

  • Comparing frequency of measurable or observable characteristics
  • Comparing base sequence DNA
  • Comparing base sequence mRNA
  • Comparing amino acid sequence of a specific protein encoded by DNA and mRNA
• Explain how comparing DNA, mRNA and amino acid sequences can indicate relationships between organisms within a species and between species:

  • More differences in sequences -> more distantly related / earlier common ancestor
  • As mutations build up over time
  • More mutations cause more changes in amino acid sequences
• Explain the change in methods of investigating genetic diversity over time:

  • Early estimates made by inferring DNA differences from measurable or observable characteristics

  -Many coded for by more than one gene -> difficult to distinguish one from another

  -Many influenced by environment -> differences due to environment not genes

  • Gene technologies allowed this to be replaced by direct investigation of DNA sequences
• Explain the key considerations in quantitative investigations of variation within a species:

  • Collect data from random samples -> removes bias
  • Use large sample size -> representative of whole population
  • Ethical sampling -> must not harm organism
  • Calculate a mean value of collected data and standard deviation of that mean
  • Interpret mean values and their Standard Deviations

  -S.D shows spread of values about mean -> higher S.D = Higher mean

  • Use statistical test -> analyse whether there is a significant difference between populations