Cladogram

A horizontal cladogram, with the root to the left
Two vertical cladograms, the root at the bottom

A cladogram (from Greek clados "branch" and gramma "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to descendants, nor does it show how much they have changed, so many differing evolutionary trees can be consistent with the same cladogram.[1][2][3][4][5] A cladogram uses lines that branch off in different directions ending at a clade, a group of organisms with a last common ancestor. There are many shapes of cladograms but they all have lines that branch off from other lines. The lines can be traced back to where they branch off. These branching off points represent a hypothetical ancestor (not an actual entity) which can be inferred to exhibit the traits shared among the terminal taxa above it.[4][6] This hypothetical ancestor might then provide clues about the order of evolution of various features, adaptation, and other evolutionary narratives about ancestors. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational phylogenetics are now very commonly used in the generation of cladograms, either on their own or in combination with morphology.

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  4. ^ a b Posada, David; Crandall, Keith A. (2001). "Intraspecific gene genealogies: Trees grafting into networks". Trends in Ecology & Evolution. 16 (1): 37–45. doi:10.1016/S0169-5347(00)02026-7. PMID 11146143.
  5. ^ Podani, János (2013). "Tree thinking, time and topology: Comments on the interpretation of tree diagrams in evolutionary/phylogenetic systematics" (PDF). Cladistics. 29 (3): 315–327. doi:10.1111/j.1096-0031.2012.00423.x. PMID 34818822. S2CID 53357985. Archived (PDF) from the original on 2017-09-21.
  6. ^ Schuh, Randall T. (2000). Biological Systematics: Principles and Applications. ISBN 978-0-8014-3675-8.[page needed]