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The term paraphyly, or paraphyletic, derives from the two Ancient Greek words παρά (pará), meaning "beside, near", and φῦλον (phûlon), meaning "genus, species", [2] [3] and refers to the situation in which one or several monophyletic subgroups of organisms (e.g., genera, species) are left apart from all other descendants of a unique common ancestor.
The arrangement of the members of a polyphyletic group is called a polyphyly / ˈ p ɒ l ɪ ˌ f aɪ l i /. [2] It is contrasted with monophyly and paraphyly. For example, the biological characteristic of warm-bloodedness evolved separately in the ancestors of mammals and the ancestors of birds; "warm-blooded animals" is therefore a ...
An evolutionary grade is a group of species united by morphological or physiological traits, that has given rise to another group that has major differences from the ancestral group's condition, and is thus not considered part of the ancestral group, while still having enough similarities that we can group them under the same clade.
In taxonomy, a group is polyphyletic if it consists of clades from multiple separate branches of the tree of life, not forming a complete clade. This classification is often due to phenotypes that have converged or reverted so as to appear to be the same but which have not been inherited from common ancestors.
[61] [62] Groups that have descendant groups removed from them are termed paraphyletic, [61] while groups representing more than one branch from the tree of life are called polyphyletic. [61] [62] Monophyletic groups are recognized and diagnosed on the basis of synapomorphies, shared derived character states. [63]
In this form, monophyletic means "no sideways stems leaving the group". A cladogram of the primates, showing a monophyletic taxon: the simians (in yellow); a paraphyletic taxon: the prosimians (in cyan, including the red patch); and a polyphyletic group: the night-active primates, i.e., the lorises and the tarsiers (in red).
In biological phylogenetics, a clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group, [1] is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. [2]
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and all descendants of that ancestor excluding one or more subgroups. See also the categories Polyphyletic groups and Obsolete taxa