Written by the Fiveable Content Team โข Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 examโขWritten by the Fiveable Content Team โข Last updated September 2025
Definition
Sister taxa are two species that share the most recent common ancestor on a phylogenetic tree. They are closely related to each other and diverged from their common ancestor more recently than any other taxa present in the tree.
Related terms
Node: Nodes represent points on a phylogenetic tree where lineages split or diverge from each other, indicating speciation events.
An outgroup is a taxon that is closely related to the group being studied but diverged from it earlier. It helps to determine the ancestral character states and root the phylogenetic tree.
Monophyletic Group: A monophyletic group, also known as a clade, consists of an ancestor and all of its descendants. Sister taxa are part of the same monophyletic group on a phylogenetic tree.