Clade

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In cladistics, a clade is a group of organisms consisting of a single common ancestor and all the descendants of that ancestor. Any such group is also considered a monophyletic group of organisms, and can be modelled by a cladogram, a diagram of the organisms in the form of a tree.

A clade is a scientific hypothesis of evolutionary relationships among the organisms included in the analysis. A particular clade may therefore be supported or disproved by a subsequent analysis using a different set of data.

If a clade proves robust in different cladistic analyses using different sets of data, it may be adopted into taxonomy and become a taxon. Not all taxa, however, are considered to be clades. Reptiles, for example, is a paraphyletic group because it does not include the birds, which are supposed to also have evolved from the common ancestor of the reptiles. The tendency, however, is to move to more cladistic taxonomy i.e. to reorganize taxa to form pure clades. ^{[citation needed]}

The PhyloCode is an attempt at a Code that would allow clades to get a formal name.

Topics in phylogenetics v • d • e</div>
Relevant fields: phylogenetics \| computational phylogenetics \| molecular phylogeny \| cladistics
Basic concepts: synapomorphy \| phylogenetic tree \| phylogenetic network \| long branch attraction
Phylogeny inference methods: maximum parsimony \| maximum likelihood \| neighbour joining \| UPGMA \| Bayesian inference
Current topics: PhyloCode \| DNA barcoding
List of evolutionary biology topics

Basic topics in evolutionary biology v • d • e</div>
Evidence of evolution
Processes of evolution: adaptation - macroevolution - microevolution - speciation
Population genetic mechanisms: selection - genetic drift - gene flow - mutation
Evo-devo concepts: phenotypic plasticity - canalisation - modularity
Modes of evolution: anagenesis - catagenesis - cladogenesis
History: History of evolutionary thought - Charles Darwin - The Origin of Species - modern evolutionary synthesis
Other subfields: ecological genetics - human evolution - molecular evolution - phylogenetics - systematics
List of evolutionary biology topics \| Timeline of evolution