A clade is a term belonging to the discipline of cladistics. For all practical purposes it will usually refer to :
- a branch in a cladogram, which is a diagram in the form of a tree resulting from a cladistic analysis.
- a monophyletic group of organisms, i.e. a group of organisms which share a common ancestor and which includes the ancestor and all the descendents of that ancestor.
Strictly speaking, a clade is a scientific hypothesis of evolutionary relationships among the organisms included in the analysis, based on the data considered in a cladistic analysis. Therefore, it will depend upon the data used to produce it; a particular clade may be supported or disproved by a subsequent analysis using different data.
If a clade proves robust in different analyses using different kinds of data, it may be translated to taxonomy: it will become a taxon, and may get a formal name and a rank. The idea that all taxa should be clades enjoys widespread support, but it remains controversial. A clade may or may not conform to an existing taxon, and vice versa: see also grade.
The PhyloCode is an attempt at a Code that would allow clades to get a formal name.
The content of this page is retrieved from http://en.wikipedia.org/wiki/Clade under GFDL
