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". 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. 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.
1 Etymology 2 History of nomenclature and taxonomy 3 Definitions 4 Clades and phylogenetic trees 5 Terminology 6 In popular culture 7 See also 8 Notes 9 References 10 External links
The term "clade" was coined in 1957 by the biologist
History of nomenclature and taxonomy
Early phylogenetic tree by Haeckel, 1866. Groups once thought to be
more advanced, such as birds ("Aves"), are placed at the top.
The idea of a clade did not exist in pre-Darwinian Linnaean taxonomy,
which was based by necessity only on internal or external
morphological similarities between organisms – although as it
happens, many of the better known animal groups in Linnaeus' original
Definitions Gavialidae, Crocodylidae and Alligatoridae are clade names that are here applied to a phylogenetic tree of crocodylians. A clade is by definition monophyletic, meaning that it contains one ancestor (which can be an organism, a population, or a species) and all its descendants.[note 1] The ancestor can be known or unknown; any and all members of a clade can be extant or extinct.
Clades and phylogenetic trees
Main article: Phylogenetics
Main article: Cladistics
The science that tries to reconstruct phylogenetic trees and thus
discover clades is called phylogenetics or cladistics, the latter term
A clade located within a clade is said to be nested within that clade.
In the diagram, the hominoid clade, i.e. the apes and humans, is
nested within the primate clade.
Two clades are sisters if they have an immediate common ancestor. In
the diagram, lemurs and lorises are sister clades, while humans and
tarsiers are not.
A clade A is basal to a clade B if A branches off the lineage leading
to B before the first branch leading only to members of B. In the
adjacent diagram, the strepsirrhine/prosimian clade, is basal to the
hominoids/ape clade. However, in this example, both Haplorrhine as
prosimians should be considered as most basal groupings. It is better
to say that the prosimians are the sister group to the rest of the
primates. This way one also avoids unintended and
misconceived connotations about evolutionary advancement, complexity,
diversity, ancestor status, and ancienity e.g. due to impact of
sampling diversity and extinction.[citation
needed] Basal clades should not be
confused with stem groupings, as the latter is associated with
paraphyletic or unresolved groupings.
In popular culture
Adaptive radiation Binomial nomenclature Biological classification Cladistics Crown group Monophyly Paraphyly Phylogenetic network Phylogenetic nomenclature Phylogenetics Polyphyly
^ A semantic case has been made that the name should be "holophyletic", but this term has not acquired widespread use. For more information, see holophyly.
^ Cracraft, Joel; Donoghue, Michael J., eds. (2004). "Introduction". Assembling the Tree of Life. Oxford University Press. p. 1. ISBN 978-0-19-972960-9..mw-parser-output cite.citation font-style:inherit .mw-parser-output .citation q quotes:"""""""'""'" .mw-parser-output .citation .cs1-lock-free a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center .mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center .mw-parser-output .citation .cs1-lock-subscription a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center .mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration color:#555 .mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span border-bottom:1px dotted;cursor:help .mw-parser-output .cs1-ws-icon a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center .mw-parser-output code.cs1-code color:inherit;background:inherit;border:inherit;padding:inherit .mw-parser-output .cs1-hidden-error display:none;font-size:100% .mw-parser-output .cs1-visible-error font-size:100% .mw-parser-output .cs1-maint display:none;color:#33aa33;margin-left:0.3em .mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format font-size:95% .mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left padding-left:0.2em .mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right padding-right:0.2em
^ a b Palmer, Douglas (2009). Evolution: The Story of Life. Berkeley: University of California Press. p. 13.
^ Pace, Norman R. (18 May 2006). "Time for a change". Nature. 441 (7091): 289. Bibcode:2006Natur.441..289P. doi:10.1038/441289a. ISSN 1476-4687. PMID 16710401.
^ Dupuis, Claude (1984). "Willi Hennig's impact on taxonomic thought". Annual Review of Ecology and Systematics. 15: 1–24. doi:10.1146/annurev.es.15.110184.000245.
^ Huxley, J. S. (1957). "The three types of evolutionary process". Nature. 180 (4584): 454–455. Bibcode:1957Natur.180..454H. doi:10.1038/180454a0.
^ a b Huxley, T.H. (1876): Lectures on Evolution. New York Tribune. Extra. no 36. In Collected Essays IV: pp 46-138 original text w/ figures
^ Brower, Andrew V. Z. (2013). "Willi Hennig at 100". Cladistics. 30 (2): 224–225. doi:10.1111/cla.12057.
^ "International Code of Phylogenetic Nomenclature. Version 4c. Chapter I. Taxa". 2010. Retrieved 22 September 2012.
^ Envall, Mats (2008). "On the difference between mono-, holo-, and paraphyletic groups: a consistent distinction of process and pattern". Biological Journal of the Linnean Society. 94: 217. doi:10.1111/j.1095-8312.2008.00984.x.
^ Nixon, Kevin C.; Carpenter, James M. (1 September 2000). "On the Other "Phylogenetic Systematics"". Cladistics. 16 (3): 298–318. doi:10.1111/j.1096-0031.2000.tb00285.x.
^ a b Krell, F.-T. & Cranston, P. (2004). "Which side of the tree is more basal?". Systematic Entomology. 29 (3): 279–281. doi:10.1111/j.0307-6970.2004.00262.x.
^ Smith, Stacey (19 September 2016). "For the love of trees: The ancestors are not among us". For the love of trees. Retrieved 23 March 2019.
^ "Choosing the Book title 'Clade'". Penguin Group Australia. 2015. Retrieved 20 January 2015.
Look up clade in Wiktionary, the free dictionary.
Evolving Thoughts: Clade
DM Hillis, D Zwickl & R Gutell. "Tree of life". An unrooted
cladogram depicting around 3000 species.
Phylogenetic systematics, an introductory slide-show on evolutionary
trees University of California, Berkeley
Long branch attraction