Investigating diverity

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

  ● Comparing frequency of measurable or observable characteristics

  ● Comparing base sequence of DNA

  ● Comparing base sequence of 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 (change in DNA base sequences) 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 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 + S.D of mean

  ● Interpret mean values + their standard deviations

  ○ S.D shows spread of values about mean → ↑ S.D = ↑ variation

  ○ S.D overlap, causing values of 2 sets of data to be shared, any difference due to chance / not signif

  ● Use statistical test → analyse whether there is a sig diff between pops