What is the Difference between Monophyletic and Polyphyletic?
In biological taxonomy — also called scientific classification or biological classification — monophyly means a group exclusively includes a species and all its ancestors, while polyphyly means a group may contain a “grab bag” of different families. These are called monophyletic and polyphyletic groups respectively. An example of a polyphyletic group would be “worms” or “warm-blooded animals,” while a monophyletic group would be “mammals” or “crustaceans.” The history of biological taxonomy has been one of trying to eliminate polyphyletic groups in favor of monophyletic ones. Since the 1970s, this has been made much easier by genetic methods — also called phylogenetic analysis or “molecular studies” — which study similar lengths of DNA to find how animals are related to one another. Many groups which look superficially similar may be found to be entirely unrelated in practice. For instance, Pygopodidae, a family of legless lizards, appear similar to snakes but are distinguished from th
