Clade
From Free net encyclopedia
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.
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| Basic topics in evolutionary biology | (edit) |
|---|---|
| Processes of evolution: evidence - macroevolution - microevolution - speciation | |
| Mechanisms: selection - genetic drift - gene flow - mutation - phenotypic plasticity | |
| Modes: anagenesis - catagenesis - cladogenesis | |
| History: History of evolutionary thought - Charles Darwin - The Origin of Species - modern evolutionary synthesis | |
| Subfields: population genetics - ecological genetics - human evolution - molecular evolution - phylogenetics - systematics - evo-devo | |
| List of evolutionary biology topics | Timeline of evolution | Timeline of human evolution |