Autapomorphy

In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon.

[4] Because autapomorphies are only present in a single taxon, they do not convey information about relationship.

However, autapomorphy, like synapomorphy and plesiomorphy is a relative concept depending on the taxon in question.

This definition assigns species on the basis of amount of divergence associated with reproductive incompatibility, which is measured essentially by number of autapomorphies.

In other words, if a peripheral population breaks away and becomes reproductively isolated, it would conceivably need to develop at least one autapomorphy to be recognized as a different species.

Phylogenies showing the terminology used to describe different patterns of ancestral and derived character or trait states. ^{[

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