In this phylogenetic tree, the monophyleticblue and red groups do not share an immediate common ancestor, as the former more recently emerged from the green group. The more distantly related blue and red groups may thus be categorized as polyphyletic based on shared traits.Cladogram of the primates, showing a monophyly (the simians, in yellow), a paraphyly (the prosimians, in cyan, including the red patch), and a polyphyly (the night-active primates, the lorises and the tarsiers, in red).Phylogenetic groups: A monophyletic taxon (in yellow, the clade Sauropsida grouping "reptiles and birds") contains a common ancestor and all of its descendants. A paraphyletic taxon (in cyan, the "reptiles") contains its most recent common ancestor, but does not contain all the descendants of that ancestor. A polyphyletic taxon (in red, the group Haemothermia containing warm-blooded tetrapods) does not contain the most recent common ancestor of all its members.
A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of convergent evolution. It is contrasted with monophyly and paraphyly.
Although polyphyly may be convenient for grouping hybrids and some species, many taxonomists prefer to avoid homoplasies in grouping taxa, preferring their monophyletic organization.
