Polyphyletic

Polyphyletic is a term used in taxonomy to describe a group of organisms that are derived from more than one common evolutionary ancestor or ancestral group, and therefore not suitable to be placed in the same taxon. This is in contrast to groups that are monophyletic (all descendants of a single common ancestor) and paraphyletic (all descendants of a common ancestor excluding some specific descendant group).

Definition

The term "polyphyletic" was coined by Ernst Haeckel in 1866. It is used to refer to a group of organisms that are classified together but do not share an immediate common ancestor. This is in contrast to a monophyletic group, which includes a common ancestor and all of its descendants, and a paraphyletic group, which includes a common ancestor and some, but not all, of its descendants.

Examples

An example of a polyphyletic group is the algae. Algae are a diverse group of aquatic organisms that have the ability to conduct photosynthesis. However, they do not share a common ancestor and are therefore polyphyletic. Other examples of polyphyletic groups include the protists, invertebrates, and fish.

Criticism

The concept of polyphyly has been criticized by some scientists who argue that all groups of organisms are ultimately polyphyletic. This is because all organisms can be traced back to a single common ancestor, the Last Universal Common Ancestor (LUCA). However, this criticism is generally not accepted by the scientific community, as it would render the concept of monophyly meaningless.

See also

• Cladistics
• Phylogenetic tree
• Phylogenetics

Polyphyletic Resources
Latest articles Most recent articles Ongoing trials	Wikipedia