Cladistics

Definition

Cladistics is a method used to classify organisms based on common ancestry and evolutionary relationships. It involves constructing cladograms that visualize these relationships in a tree-like diagram.

5 Must Know Facts For Your Next Test

1. Cladistics focuses on shared derived characteristics (synapomorphies) to group organisms.
2. A clade includes an ancestor and all its descendants, representing a single branch on the tree of life.
3. Cladograms are not necessarily based on physical similarities but on evolutionary history.
4. Homoplasy, or convergent evolution, can complicate cladistic analysis by introducing similar traits in unrelated lineages.
5. Molecular data, such as DNA sequences, are increasingly used in cladistic analysis for more accurate results.

Review Questions

• What is the primary focus of cladistics when classifying organisms?
• How does a clade differ from other taxonomic groups?
• Why might molecular data be preferred over morphological traits in some cladistic analyses?

Related terms

Phylogeny:

The study of evolutionary relationships among species.

Synapomorphy: A characteristic present in an ancestral species and shared exclusively by its evolutionary descendants.

Homoplasy: A trait that has arisen independently in different species due to convergent evolution rather than common ancestry.