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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). A cladogram of the ...
The term polyphyly, or polyphyletic, derives from the two Ancient Greek words πολύς (polús) 'many, a lot of', and φῦλον (phûlon) 'genus, species', [8] [9] and refers to the fact that a polyphyletic group includes organisms (e.g., genera, species) arising from multiple ancestral sources.
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]
A polyphyletic assemblage is one which is neither monophyletic nor paraphyletic. A polyphyletic assemblage is characterized by one or more homoplasies: character states which have converged or reverted so as to be the same but which have not been inherited from a common ancestor. No systematist recognizes polyphyletic assemblages as ...
This is an example of a paraphyletic group, a clade minus one or more subordinate clades. Names of polyphyletic groups, characterized by a trait that evolved convergently in two or more subgroups, can be defined similarly as the sum of multiple clades. [5]
[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]
Cladogram (family tree) of a biological group. The green box (central) may represent an evolutionary grade (paraphyletic), a group united by conservative anatomical and physiological traits rather than phylogeny. The flanking red and blue boxes are clades (i.e., complete monophyletic subtrees).
They held that only monophyletic groups should be accepted as formal ranks in a classification and that – while this approach had been impractical previously (necessitating "literally dozens of eukaryotic 'kingdoms '") – it had now become possible to divide the eukaryotes into "just a few major groups that are probably all monophyletic".