Symplesiomorphy

Definition

An ancestral trait shared by two or more taxa. In the context of phylogenetics, it refers to a characteristic that was present in the last common ancestor of a group but is not unique to that group.

Etymology

From Greek 'sym-', meaning 'together', 'plesio-', meaning 'near', and 'morphē', meaning 'form' or 'shape'.

Example

The presence of wings in both butterflies and moths is a symplesiomorphy, as it is inherited from their common ancestor.

Synonyms

• Ancestral character
• Primitive trait

Related Terms

• Synapomorphy
• Homology
• Phylogenetics
• Cladistics

Usage Notes

Symplesiomorphies can be problematic in constructing phylogenetic trees because they do not provide information about the unique evolutionary relationships within a group.