Monophyly

Encyclopedia : M : MO : MON : Monophyly

In phylogenetics, a group is monophyletic (Greek: "of one race") if it consists of a common ancestor and all its descendants. A taxonomic group that contain organisms but not their common ancestor is called polyphyletic, and a group that contains some but not all descendants of the most recent common ancestor is called paraphyletic.

The grouping of reptiles and birds is generally believed to be monophyletic.

For example, all organisms in the genus Homo are believed to have come from the same ancestral form in the family Hominidae, and no other descendants are known. Thus the genus Homo is monophyletic. If, on the other hand, it were discovered that Homo habilis had developed from a different ancestor than Homo sapiens, and this ancestor were not included in the genus, then the genus would be polyphyletic. Since biologists by and large prefer groups to be monophyletic, in this case, they would likely either split the genus or broaden it to include the additional forms.

Evolutionary taxonomists use the term holophyletic for the sort of groups discussed here, whereby monophyly includes both holophyly and paraphyly.

See also

• taxonomy
• Linnaean taxonomy
• cladistics
• evolutionary taxonomy

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.