What does monophyletic mean?
Monophyletic describes an evolutionary group whose members share a single common ancestor and which includes every descendant of that ancestor. The concept is central to modern biological classification because it treats evolutionary relationships as branching lineages rather than as superficial similarities in form or behavior. For example, whales can be recognized as a monophyletic group because they share a common ancestor and include all of its descendants within the even-toed mammals. A classification that includes the ancestor but leaves out some descendants is paraphyletic, while one that combines separate lineages without their most recent common ancestor is polyphyletic. The term is therefore not simply a synonym for “a group of related organisms”: it specifies a particular and exact kind of relationship. It is most often encountered in biology, paleontology, and taxonomy, especially in discussions of clades and the reconstruction of evolutionary trees.
adjectiveRelating to or constituting a group of organisms descended from a single common ancestor and containing all of that ancestor's descendants.
- Pertaining to a group of organisms that includes a common ancestor and all of that ancestor's descendants.
"The revised classification recognizes whales as a monophyletic group within the even-toed mammals."
"The revised classification recognizes whales as a monophyletic group within the even-toed mammals."
"The chart marks each lineage as monophyletic only when it includes an ancestor and every descendant of that ancestor."
A monophyletic group is a complete evolutionary branch; leave out even one descendant and it becomes paraphyletic.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does monophyletic come from?
Monophyletic combines the Greek prefix mono-, meaning “single” or “alone,” with phylo-, derived from Greek phulē, meaning “race” or “stock.” The resulting term describes a group united by descent from one ancestor. It belongs to the same scientific family of words as phylogeny and phylogenetic, which likewise concern evolutionary descent and relationships.
Related word forms
How monophyletic is actually used
This is a specialized term used chiefly in evolutionary biology, taxonomy, and phylogenetics. It normally characterizes a group, taxon, or lineage.
Easily confused with monophyletic
A monophyletic group includes an ancestor and all its descendants, whereas a paraphyletic group includes the ancestor but excludes some descendants.
A monophyletic group traces to one common ancestor, whereas a polyphyletic grouping combines lineages without including their most recent common ancestor as part of the group.