Out-group

Definition

In phylogenetics, an out-group is a species or group of species that is closely related to but not part of the group being studied. It serves as a reference point for determining evolutionary relationships within the group under study.

Related terms

In-group: The set of taxa which is hypothesized to be monophyletic and is being analyzed in any given phylogenetic study.

Monophyletic Group: A set of organisms or other evolving elements that have been derived from a single ancestral form and includes all descendants.

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