Polyphyletic

Definition

Polyphyletic refers to a group of organisms that are classified together but do not share an immediate common ancestor. This classification is based on convergent traits rather than genetic lineage.

5 Must Know Facts For Your Next Test

1. Polyphyletic groups are identified based on convergent evolution, where unrelated species independently evolve similar traits.
2. In microbiology, polyphyly can complicate the study of eukaryotic parasites since it groups organisms with different evolutionary backgrounds.
3. Polyphyletic classifications are often revised as genetic and molecular data become available, providing clearer evolutionary relationships.
4. A polyphyletic group contrasts with monophyletic and paraphyletic groups, which include organisms that do share a common ancestor.
5. Understanding polyphyly helps in identifying traits that have evolved multiple times across different lineages, such as certain pathogenic mechanisms in unicellular eukaryotic parasites.

Review Questions

• What is a defining characteristic of a polyphyletic group?
• How does polyphyly affect the classification of eukaryotic parasites?
• Why might a polyphyletic classification be revised with new genetic data?

Related terms

Monophyletic: A group of organisms that includes an ancestor and all its descendants.

Paraphyletic: A group of organisms that includes an ancestor but not all its descendants.

Convergent Evolution: The process where unrelated organisms independently evolve similar traits.