Essential Idea:  The ancestry of groups of species can be deduced by comparing their base or amino acid sequences.
At SHS, Topic 5.4 is taught in the following class unit(s):​​​​​​
5.4.U1  A clade is a group of organisms that have evolved from a common ancestor.
  • Define clade and cladistics.
5.4.U2  Evidence for which species are part of a clade can be obtained from the base sequences of a gene or the corresponding amino acid sequence of a protein.
  • Outline the relationship between time, evolutionary relationships and biological sequences (nitrogenous base or amino acid).
5.4.U3  Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor.​
  • Outline the use of a “molecular clock” to determine time since divergence between two species.
  • State the source of differences between biological sequences (nitrogenous base or amino acid).
5.4.U4  Traits can be analogous or homologous.​
  • Contrast analogous and homologous traits.
  • State an example of analogous and homologous traits.
5.4.U5  Cladograms are tree diagrams that show the most probable sequence of divergence in clades.​
  • Define cladogram and node.
  • Outline how computer programs analyze biological sequence data to create cladograms.
  • Identify members of clades given a cladogram.
5.4.U6  Evidence from cladistics has shown that classifications of some groups based on structure did not correspond with the evolutionary origins of a group or species.​
  • Outline the role of technological advancements in the development of cladistics.
  • Explain why the development of cladistics lead to the reclassification of some species.
5.4.A1  Cladograms including human and other primates.
  • Interpret a cladogram depicting primate species. ​
5.4.A2  Reclassification of the figwort family using evidence from cladistics.
  • Outline the reason and evidence for the reclassification of the figwort family.
5.4.S1  Analysis of cladograms to deduce evolutionary relationships.​
  • Analyze a cladogram to explain the evolutionary relationship between species.
  • Discuss the use of cladograms as hypotheses of evolutionary relationships.
5.4.NOS  Falsification of theories with one theory being superseded by another- plant families have been reclassified as a result of evidence from cladistics.
  • Outline the reason why biological theories may change with time.

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