Holophyletic is a term posited as a semantically correct replacement for the term monophyletic as used by cladists (which differs from the usage of evolutionary systematists).[1] It originated amidst confusion over the correct definition for 'monophyletic group'; many definitions were available, of varying degrees of restrictiveness, and 'holophyletic' was posited as a term to describe the definition with scientific utility.[1] The least scientifically useful definition for monophyletic, which is arguably the semantically correct one, considers any group of organisms with a common ancestor to be a monophyletic group.[2] Since it is presumed that one could find a common ancestor from any group of organisms if one goes far enough into the past, this definition implicitly or explicitly constrains what is a legitimate common ancestor, for example by requiring the common ancestor to share a derived trait (synapomorphy) which defines the group.[1]
The term holophyletic refers specifically to the definition that a group contains the common ancestor, all organisms descended from the common ancestor, and no other organisms.
The term holophyletic has not gained widespread acceptance in the scientific community,[3] probably because the term 'monophyletic' is so widely used with the same widely understood meaning.
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