In Situ Hybridisation

Molecular evidence for phylogenetic relationships involves identifying conservation in DNA or amino acid sequences

One technique used to identify conservation in gene sequences is DNA DNA hybridisation

  • DNA is double stranded and is held together by hydrogen bonds between complementary base pairs
  • DNA from different species can be separated into single strands with sufficient heat and then mixed together
  • If two strands from different species share similar sequences they will hybridise (anneal together to form a double strand)
  • The amount of heat then required to separate this hybrid molecule indicates how similar the two sequences are
  • More heat indicates more hydrogen bonds formed, meaning more complementary base pairing due to similar sequences
  • Less heat indicates fewer hydrogen bonds formed, meaning less base pairing has occurred because sequences are dissimilar

DNA-DNA Hybridisation

in situ hybridisation