A 3.2.7 - Biology study for cladistics

What is the definition of a cladogram?

• A branching tree diagram showing evolutionary relationships among organisms.

What does the root at the bottom of a cladogram represent?

• The common ancestor shared by all organisms in the diagram.

What does a node (branching point) represent?

• A hypothetical common ancestor and a speciation/divergence event.

What do the terminal branches (taxa at the ends) represent?

• Individual species, groups, or specific taxa being compared.

What is an outgroup on a cladogram?

• The most distantly related species branching closest to the root.

If you rotate branches at a node, does it change the depicted evolutionary relationships?

No, the evolutionary relationships remain exactly the same.

True or False: A straight lineage line on a cladogram means no evolutionary change has occurred.

• False, contemporary lineages have all been evolving for the same amount of time.

How do you find the most recent common ancestor between two specific taxa?

• Trace their branches backward to find the first shared intersecting node.

How do you determine which organisms are most closely related on a cladogram?

• Look for the taxa that share the most recent common node.