Basal (phylogenetics)
- Basal (phylogenetics)
In
phylogenetics , a basalclade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram. A basal group form anoutgroup to 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
derived if 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.References
Wikimedia Foundation. 2010.
Look at other dictionaries:
Basal angiosperms — Nymphaea alba, from the Nymphaeales The basal angiosperms are the first flowering plants to diverge from the ancestral angiosperm. In particular, the most basal angiosperms are the so called ANITA grade which is made up of Amborella (a single… … 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
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 .[1]… … Wikipedia
Rodrigues Starling — Conservation status Extinct (IUCN 3.1) Scientific classification Kingdom … Wikipedia
Origin of birds — For the book by Gerhard Heilmann, see The Origin of Birds (book). The famous Berlin specimen of Archaeopteryx lithographica The origin of birds is a contentious and central topic within evolutionary biology. A close relationship between birds and … Wikipedia
Diplomystes — Scientific classification Kingdom: Animalia Phylum: Chordata Class: Actinopterygii … Wikipedia
Annelid — Temporal range: Early Ordovician–Recent[1] … Wikipedia
Fungus — Fungi redirects here. You may be looking for Fungi (music) or Fungus (XM). Fungi Temporal range: Early Devonian–Recent (but see text) … 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
Insect morphology — Legend of body parts Tagmata : A Head, B Thorax, C Abdomen. 1. antenna 2. ocelli (lower) 3. ocelli (upper) 4. compound eye 5. brain (cerebral ganglia) 6. prothorax … Wikipedia
