- Basal (phylogenetics)
phylogenetics, a basal cladeis the earliest clade to branch in a larger clade; it appears at the base of a cladogram. A basal group form an outgroupto the rest of the clade.
The word "basal" is preferred to the loaded term "primitive", which has false connotations of inferiority or simplicity.
The basal status of a clade is relative to what it is being compared to. In the first example below, humans are the basal group, as they are the first to diverge from the lineages of plant. In the second example, plants are basal to the animals considered.
The term basal can only be correctly applied to clades, not to traits - although it is frequently misused in the literature! While the term "basal" applies to clades, "characters" or traits are usually considered
derivedif they are absent in a basal group, but present in other groups. This assumption only holds true if the basal group is a good analogy for the last common ancestor of the group: in the example of plants and apes above, it would be likely to break down.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Primitive (phylogenetics) — Primitive is a descriptive term often used in the field of evolution to describe particular species or traits that are characteristic of an older evolutionary scale of development relative to more recent developments. For example, prokaryotes… … Wikipedia
Terminology for Asteraceae — NOTOC accrescent *Growing larger after flowering.1913] achene *achene *A small, dry, indehiscent fruit, containing a single seed, as in the buttercup; called a naked seed by the earlier botanists. *small dry indehiscent fruit with the seed… … Wikipedia
Evolution of mammals — Restoration of Thrinaxodon, a member of the cynodont group, which includes the ancestors of mammals Further information: Evolutionary history of life The evolution of mammals within the synapsid lineage (sometimes called mammal like reptiles )… … Wikipedia
Cladistics — For the scientific journal, see Cladistics (journal). Part of a series on Evolutionary Biology … Wikipedia
Sistema de clasificación APG III — Diagrama simplificado que ilustra el árbol filogenético de las angiospermas. Se muestran los grandes grupos de angios … Wikipedia Español
Cnidaria — Temporal range: 580–0 Ma … Wikipedia
Paleontology — Palaeontology redirects here. For the scientific journal, see Palaeontology (journal). Paleontology studies the entire history of life on Earth. Paleontology (pronounced /ˌpælɪɒnˈtɒlədʒi/; British: palaeontology; from Greek: παλαιός… … Wikipedia
Ctenophora — For the genus of crane flies, see Ctenophora (genus). Comb jellies Temporal range: Cambrian – Recent … Wikipedia
Unplaced in APG II — When the APG II system of plant classification was published in April 2003, fifteen genera and three families were placed incertae sedis in the angiosperms, and were listed in a section of the appendix entitled Taxa of uncertain position .… … Wikipedia
Temnospondyli — Temnospondyls Temporal range: Early Carboniferous Early Cretaceous, 330–120 Ma Possible descendant taxon Lissamphibia survives to present … Wikipedia