Clade

Cladogram (family tree) of a biological group, showing the last common ancestor of the composite tree, which is the vertical line 'trunk' (stem) at the bottom, with all descendant branches shown above. The blue and red subgroups (at left and right) are clades, or monophyletic (complete) groups; each shows its common ancestor 'stem' at the bottom of the subgroup 'branch'. The green subgroup is not a clade; it is a paraphyletic group, which is an incomplete clade here because it excludes the blue branch even though it has also descended from the common ancestor stem at the bottom of the green branch. The green subgroup together with the blue one forms a clade again.

A clade (from Ancient Greek: κλάδος, klados, "branch"), also known as monophyletic group, is a group of organisms that consists of a common ancestor and all its lineal descendants, and represents a single "branch" on the "tree of life".[1]

The common ancestor may be an individual, a population, a species (extinct or extant), and so on right up to a kingdom and further. Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups.

Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms.[2] Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between organisms that the molecular biology arm of cladistics has revealed are that fungi are closer relatives to animals than they are to plants, archaea are now considered different from bacteria, and multicellular organisms may have evolved from archaea.[3]

Etymology

The term "clade" was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis, a concept Huxley borrowed from Bernhard Rensch.[4][5]

Many commonly named groups, rodents and insects for example, are clades because, in each case, the group consists of a common ancestor with all its descendant branches. Rodents, for example, are a branch of mammals that split off after the end of the period when the clade Dinosauria stopped being the dominant terrestrial vertebrates 66 million years ago. The original population and all its descendants are a clade. The rodent clade corresponds to the order Rodentia, and insects to the class Insecta. These clades include smaller clades, such as chipmunk or ant, each of which consists of even smaller clades. The clade "rodent" is in turn included in the mammal, vertebrate and animal clades.

Other Languages
Afrikaans: Klade
العربية: فرع حيوي
aragonés: Clado
azərbaycanca: Klad
беларуская: Клада
български: Клон (еволюция)
bosanski: Kladus
català: Clade
čeština: Klad
Deutsch: Klade
eesti: Klaad
Ελληνικά: Κλάδος
español: Clado
Esperanto: Klado
euskara: Klado
فارسی: کلاد
français: Clade
Gaeilge: Clád
Gaelg: Clade
galego: Clado
한국어: 계통군
हिन्दी: क्लेड
Bahasa Indonesia: Klad
interlingua: Clado
italiano: Clade
Basa Jawa: Klade
Latina: Cladus
Limburgs: Klaad
magyar: Klád
македонски: Клад
മലയാളം: ക്ലാഡ്
Malti: Klad
मराठी: क्लेड
Bahasa Melayu: Klad
Nederlands: Clade
日本語: 系統群
norsk: Klade
Plattdüütsch: Klade
polski: Klad
português: Clado
română: Cladă
русский: Клада
Scots: Clade
slovenščina: Klad
српски / srpski: Kladus
srpskohrvatski / српскохрватски: Kladus
suomi: Kladi
svenska: Klad
ไทย: เคลด
українська: Клада
vèneto: Clade
Tiếng Việt: Nhánh
West-Vlams: Clade
中文: 演化支