By analysing cladograms, biologists can deduce common ancestry, relatedness, and evolutionary pathways.
Key Features of a Cladogram
1. Root
Definition
Root
The base of the cladogram, representing the most recent common ancestor of all species in the diagram.
- The base of the cladogram.
- Represents the hypothetical common ancestor of all organisms shown.
- This ancestor may not be directly observable in fossil records but is inferred from molecular or morphological data.
2. Nodes
Definition
Node
A branching point where two or more lineages split, representing a hypothetical common ancestor shared by the diverging groups.
- Points where branches split.
- Each node represents a hypothetical common ancestor of the clades that diverge from it.
- Usually two clades split at a node (binary branching), but sometimes three or more emerge (polytomy).
3. Terminal Branches (Tips)
Definition
Terminal branch
The endpoints of the branches, representing the species or groups being studied.
- The ends of branches.
- Represent individual species or groups of species alive today (or recently extinct).
- Each terminal branch marks the end of an evolutionary lineage.
- Confusing terminal branches with ancestors.
- Terminal branches represent descendants, not ancestral forms.
- Nodes do not represent specific species we can observe today.
- Instead, they are inferred based on evidence such as DNA similarities and shared traits.
