In modern usage, a monophyletic taxon is defined as one that includes the most recent common ancestor of a group of organisms, and all of its descendents [as in (a)]. A polyphyletic taxon is defined as one that does not include the common ancestor of all members of the taxon [as in (b)].

Similarly, what is the difference between monophyletic and paraphyletic? In cladistics, a monophyletic group is a group of organisms that forms a clade, which consists of all the descendants of a common ancestor. A paraphyletic group consists of all of the descendants of a common ancestor minus one or more monophyletic groups.

Also question is, what does it mean for a clade to be monophyletic paraphyletic or Polyphyletic?

Only monophyletic groups qualify as legitimate taxa in cladistics. Paraphyletic - a group of organisms that includes an ancestor but not all of its descendants. Polyphyletic - one that does not include the common ancestor of all members of the taxon.

What is a paraphyletic group?

A paraphyletic group is a group of organisms that includes an ancestor but not all of its descendants. Learn more about paraphyletic groups and some examples of them in this lesson.