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Cladistics (; ) is an approach to
biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mecha ...
in which
organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological me ...

organism
s are categorized in groups ("
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic – that is, composed of a common ancestor and all its lineage (evolution), lineal descendants - on a phylogenetic tree. R ...

clade
s") based on hypotheses of most recent
common ancestry Common descent is a concept in evolutionary biology Evolutionary biology is the subfield of biology that studies the evolution, evolutionary processes (natural selection, common descent, speciation) that produced the Biodiversity, diversity ...
. The evidence for hypothesized relationships is typically shared derived characteristics (
synapomorphies 279px, trait states. In phylogenetics, apomorphy and synapomorphy refer to derived characters of a clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are mon ...
'')'' that are not present in more distant groups and ancestors. Theoretically, a common ancestor and all its descendants are part of the clade. However, from an empirical perspective, common ancestors are inferences based on a cladistic hypothesis of relationships of taxa whose
character states Character(s) may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to Theophrastus M ...
can be observed. Importantly, all descendants stay in their overarching ancestral clade. For example, if the terms ''worms'' or ''fishes'' were used within a ''strict'' cladistic framework, these terms would include humans. Many of these terms are normally used paraphyletically, outside of cladistics, e.g. as a '
grade Grade or grading may refer to: Arts and entertainment * Grade (band) Grade is a melodic hardcore band from Canada, often credited as pioneers in blending metallic hardcore with the hon and melody of emo, and - most notably - the alternating scr ...
'.
Radiation upThe international symbol for types and levels of ionizing radiation (radioactivity) that are unsafe for unshielded humans. Radiation, in general, exists throughout nature, such as in light and sound. In physics Physics (from grc ...
results in the generation of new subclades by bifurcation, but in practice sexual hybridization may blur very closely related groupings.Columbia EncyclopediaOxford Dictionary of EnglishOxford English Dictionary The techniques and nomenclature of cladistics have been applied to disciplines other than biology. (See
phylogenetic nomenclature In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms, ...
.) Cladistics is now the most commonly used method to classify organisms.


History

The original methods used in cladistic analysis and the school of taxonomy derived from the work of the German
entomologist upright=1.2, A Phyllium sp., mimicking a leaf Entomology () is the scientific Science () is a systematic enterprise that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions abo ...

entomologist
Willi Hennig Emil Hans Willi Hennig (20 April 1913 – 5 November 1976) was a German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of German ...

Willi Hennig
, who referred to it as phylogenetic systematics (also the title of his 1966 book); the terms "cladistics" and "clade" were popularized by other researchers. Cladistics in the original sense refers to a particular set of methods used in
phylogenetic In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...

phylogenetic
analysis, although it is now sometimes used to refer to the whole field. What is now called the cladistic method appeared as early as 1901 with a work by
Peter Chalmers Mitchell Sir Peter Chalmers Mitchell (23 November 1864 – 2 July 1945) was a Scottish zoologist who was Secretary of the Zoological Society of London from 1903 to 1935. During this time, he directed the policy of the Zoological Gardens of London and cre ...
for birdsFolinsbee, Kaila et al. 2007. 5 Quantitative Approaches to Phylogenetics, p. 172. Rev. Mex. Div. 225-52 (kfolinsb.public.iastate.edu) and subsequently by
Robert John Tillyard Robert "Robin" John Tillyard FRS FRS may also refer to: Government and politics * Facility Registry System, a centrally managed Environmental Protection Agency database that identifies places of environmental interest in the United States * F ...
(for insects) in 1921, and W. Zimmermann (for plants) in 1943. The term "
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic – that is, composed of a common ancestor and all its lineage (evolution), lineal descendants - on a phylogenetic tree. R ...

clade
" was introduced in 1958 by
Julian Huxley Sir Julian Sorell Huxley (22 June 1887 – 14 February 1975) was an English evolutionary biologist, eugenicist, and internationalist. He was a proponent of natural selection Natural selection is the differential survival and reprodu ...
after having been coined by
Lucien Cuénot Lucien Claude Marie Julien Cuénot (; 21 October 1866 – 7 January 1951) was a French biologist. In the first half of the 20th century, Mendelism was not a popular subject among French biologists. Cuénot defied popular opinion and shirked the “ ...
in 1940, "cladogenesis" in 1958,Webster's 9th New Collegiate Dictionary "cladistic" by
Arthur Cain Arthur James Cain FRS (25 July 1921 – 20 August 1999) was a British evolutionary biologist and ecologist Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between livin ...
and Harrison in 1960, "cladist" (for an adherent of Hennig's school) by
Ernst Mayr Ernst Walter Mayr (; 5 July 1904 – 3 February 2005) was one of the 20th century's leading evolutionary biologists File:Francesco Redi.jpg, Francesco Redi, the founder of biology, is recognized to be one of the greatest biologists of all ti ...
in 1965, and "cladistics" in 1966. Hennig referred to his own approach as "phylogenetic systematics". From the time of his original formulation until the end of the 1970s, cladistics competed as an analytical and philosophical approach to systematics with
phenetics In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanis ...
and so-called
evolutionary taxonomy Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of Phylogenetics, phylogenetic relationship (shared descent), progenitor-de ...
. Phenetics was championed at this time by the numerical taxonomists
Peter Sneath Peter Henry Andrews Sneath FRS FRS may also refer to: Government and politics * Facility Registry System, a centrally managed Environmental Protection Agency database that identifies places of environmental interest in the United States * Family ...
and
Robert Sokal Robert Reuven Sokal (January 13, 1926 in Vienna en, Viennese , iso_code = AT-9 , registration_plate = Vehicle registration plates of Austria, W , postal_code_type = Postal code , posta ...
, and evolutionary taxonomy by
Ernst Mayr Ernst Walter Mayr (; 5 July 1904 – 3 February 2005) was one of the 20th century's leading evolutionary biologists File:Francesco Redi.jpg, Francesco Redi, the founder of biology, is recognized to be one of the greatest biologists of all ti ...
. Originally conceived, if only in essence, by Willi Hennig in a book published in 1950, cladistics did not flourish until its translation into English in 1966 (Lewin 1997). Today, cladistics is the most popular method for inferring phylogenetic trees from morphological data. In the 1990s, the development of effective
polymerase chain reaction Polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete copies or partial copies) of a specific DNA Deoxyribonucleic acid (; DNA) is a molecule File:Pentacene on Ni(111) STM. ...

polymerase chain reaction
techniques allowed the application of cladistic methods to
biochemical Biochemistry or biological chemistry, is the study of chemical process In a scientific Science (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. L ...
and molecular genetic traits of organisms, vastly expanding the amount of data available for phylogenetics. At the same time, cladistics rapidly became popular in evolutionary biology, because
computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Computer program, programs. These ...

computer
s made it possible to process large quantities of data about organisms and their characteristics.


Methodology

The cladistic method interprets each shared character state transformation as a potential piece of evidence for grouping.
Synapomorphies 279px, trait states. In phylogenetics, apomorphy and synapomorphy refer to derived characters of a clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are mon ...
(shared, derived character states) are viewed as evidence of grouping, while symplesiomorphies (shared ancestral character states) are not. The outcome of a cladistic analysis is a
cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics Cladistics (, from Greek language, Greek , ''kládos'', "branch") is an approach to Taxonomy (biology), biological classification in whi ...

cladogram
– a
tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only wood plants with se ...
-shaped diagram (
dendrogram File:Phylogenetic tree.svg, A dendrogram of the Tree of Life. This phylogenetic tree is adapted from Woese et al. rRNA analysis. The vertical line at bottom represents the last universal common ancestor (LUCA). A dendrogram is a diagram repre ...
) that is interpreted to represent the best hypothesis of phylogenetic relationships. Although traditionally such cladograms were generated largely on the basis of morphological characters and originally calculated by hand, data and
computational phylogenetics Computational phylogenetics is the application of computational algorithm In and , an algorithm () is a finite sequence of , computer-implementable instructions, typically to solve a class of problems or to perform a computation. Algorithms ...
are now commonly used in phylogenetic analyses, and the parsimony criterion has been abandoned by many phylogeneticists in favor of more "sophisticated" but less parsimonious evolutionary models of character state transformation. Cladists contend that these models are unjustified because there is no evidence that they recover more "true" or "correct" results from actual empirical data sets Every cladogram is based on a particular dataset analyzed with a particular method. Datasets are tables consisting of
molecular A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral group of two or more atom An atom is the smallest unit of ordinary matter In ...
, morphological,
ethological Ethology is the scientific method, scientific and objective study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily Adaptive behavior (ecology), adaptive trait. Behav ...
and/or other characters and a list of
operational taxonomic unit An operational taxonomic unit (OTU) is an operational definition used to classify groups of closely related individuals. The term was originally introduced in 1963 by Robert R. Sokal Robert Reuven Sokal (January 13, 1926 in Vienna en, Vi ...
s (OTUs), which may be genes, individuals, populations, species, or larger taxa that are presumed to be monophyletic and therefore to form, all together, one large clade; phylogenetic analysis infers the branching pattern within that clade. Different datasets and different methods, not to mention violations of the mentioned assumptions, often result in different cladograms. Only scientific investigation can show which is more likely to be correct. Until recently, for example, cladograms like the following have generally been accepted as accurate representations of the ancestral relations among turtles, lizards, crocodilians, and birds:
If this phylogenetic hypothesis is correct, then the last common ancestor of turtles and birds, at the branch near the lived earlier than the last common ancestor of lizards and birds, near the . Most molecular evidence, however, produces cladograms more like this:
If this is accurate, then the last common ancestor of turtles and birds lived later than the last common ancestor of lizards and birds. Since the cladograms show two mutually exclusive hypotheses to describe the evolutionary history, at most one of them is correct. The cladogram to the right represents the current universally accepted hypothesis that all
primate A primate ( ) (from Latin , from 'prime, first rank') is a eutherian mammal constituting the Taxonomy (biology), taxonomic order (biology), order Primates (). Primates arose 85–55 million years ago first from small Terrestrial animal, ...

primate
s, including
strepsirrhines Strepsirrhini or Strepsirhini (; ) is a suborder In biological classification, the order ( la, wikt:ordo#Latin, ordo) is # a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. The well-known ranks ...

strepsirrhines
like the
lemur Lemurs ( ) (from Latin ''lemures'' – ghosts or spirits) are wet-nosed primates of the superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid s ...

lemur
s and
loris Loris is the common name for the strepsirrhine Strepsirrhini or Strepsirhini (; ) is a suborder of primate A primate ( ) (from Latin , from 'prime, first rank') is a eutherian mammal Mammals (from Latin language, Latin , 'brea ...

loris
es, had a common ancestor all of whose descendants are or were primates, and so form a clade; the name Primates is therefore recognized for this clade. Within the primates, all anthropoids (monkeys, apes, and humans) are hypothesized to have had a common ancestor all of whose descendants are or were anthropoids, so they form the clade called Anthropoidea. The "prosimians", on the other hand, form a paraphyletic taxon. The name Prosimii is not used in
phylogenetic nomenclature In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms, ...
, which names only clades; the "prosimians" are instead divided between the clades and
Haplorhini Haplorhini (), the haplorhines (Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximat ...
, where the latter contains Tarsiiformes and Anthropoidea.


Terminology for character states

The following terms, coined by Hennig, are used to identify shared or distinct character states among groups: * A
plesiomorphy In phylogenetics In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, phy ...

plesiomorphy
("close form") or ancestral state is a character state that a taxon has retained from its ancestors. When two or more taxa that are not nested within each other share a plesiomorphy, it is a symplesiomorphy (from ''syn-'', "together"). Symplesiomorphies do not mean that the taxa that exhibit that character state are necessarily closely related. For example, Reptilia is traditionally characterized by (among other things) being cold-blooded (i.e., not maintaining a constant high body temperature), whereas birds are warm-blooded. Since cold-bloodedness is a plesiomorphy, inherited from the common ancestor of traditional reptiles and birds, and thus a symplesiomorphy of turtles, snakes and crocodiles (among others), it does not mean that turtles, snakes and crocodiles form a clade that excludes the birds. * An
apomorphy 279px, trait states. In phylogenetics, apomorphy and synapomorphy refer to derived characters of a clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are mon ...
("separate form") or derived state is an innovation. It can thus be used to diagnose a clade – or even to help define a clade name in
phylogenetic nomenclature In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms, ...
. Features that are derived in individual taxa (a single species or a group that is represented by a single terminal in a given phylogenetic analysis) are called autapomorphies (from ''auto-'', "self"). Autapomorphies express nothing about relationships among groups; clades are identified (or defined) by synapomorphies (from ''syn-'', "together"). For example, the possession of digits that are homologous with those of ''Homo sapiens'' is a synapomorphy within the vertebrates. The
tetrapod Tetrapods (; ) are four-limbed animals constituting the superclass Tetrapoda (). It includes extant Extant is the opposite of the word extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a sp ...
s can be singled out as consisting of the first vertebrate with such digits homologous to those of ''Homo sapiens'' together with all descendants of this vertebrate (an apomorphy-based phylogenetic definition). Importantly, snakes and other tetrapods that do not have digits are nonetheless tetrapods: other characters, such as amniotic eggs and diapsid skulls, indicate that they descended from ancestors that possessed digits which are homologous with ours. * A character state is homoplastic or "an instance of
homoplasy Homoplasy, in biology and phylogenetics, is when a Phenotypic trait, trait has been gained or lost independently in separate lineages over the course of evolution. This is different from Homology (biology), homology, which is the similarity of trait ...

homoplasy
" if it is shared by two or more organisms but is absent from their common ancestor or from a later ancestor in the lineage leading to one of the organisms. It is therefore inferred to have evolved by convergence or reversal. Both mammals and birds are able to maintain a high constant body temperature (i.e., they are warm-blooded). However, the accepted cladogram explaining their significant features indicates that their common ancestor is in a group lacking this character state, so the state must have evolved independently in the two clades. Warm-bloodedness is separately a synapomorphy of mammals (or a larger clade) and of birds (or a larger clade), but it is not a synapomorphy of any group including both these clades. Hennig's Auxiliary Principle states that shared character states should be considered evidence of grouping unless they are contradicted by the weight of other evidence; thus, homoplasy of some feature among members of a group may only be inferred after a phylogenetic hypothesis for that group has been established. The terms plesiomorphy and apomorphy are relative; their application depends on the position of a group within a tree. For example, when trying to decide whether the tetrapods form a clade, an important question is whether having four limbs is a synapomorphy of the earliest taxa to be included within Tetrapoda: did all the earliest members of the Tetrapoda inherit four limbs from a common ancestor, whereas all other vertebrates did not, or at least not homologously? By contrast, for a group within the tetrapods, such as birds, having four limbs is a plesiomorphy. Using these two terms allows a greater precision in the discussion of homology, in particular allowing clear expression of the hierarchical relationships among different homologous features. It can be difficult to decide whether a character state is in fact the same and thus can be classified as a synapomorphy, which may identify a monophyletic group, or whether it only appears to be the same and is thus a homoplasy, which cannot identify such a group. There is a danger of circular reasoning: assumptions about the shape of a phylogenetic tree are used to justify decisions about character states, which are then used as evidence for the shape of the tree.
Phylogenetics In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...

Phylogenetics
uses various forms of parsimony to decide such questions; the conclusions reached often depend on the dataset and the methods. Such is the nature of empirical science, and for this reason, most cladists refer to their cladograms as hypotheses of relationship. Cladograms that are supported by a large number and variety of different kinds of characters are viewed as more robust than those based on more limited evidence.


Terminology for taxa

Mono-, para- and polyphyletic taxa can be understood based on the shape of the tree (as done above), as well as based on their character states. These are compared in the table below.


Criticism

Cladistics, either generally or in specific applications, has been criticized from its beginnings. Decisions as to whether particular character states are homologous, a precondition of their being synapomorphies, have been challenged as involving
circular reasoning Circular reasoning ( la, circulus in probando, "circle in proving"; also known as circular logic) is a logical fallacy in which the reasoner begins with what they are trying to end with. The components of a circular argument are often logically ...

circular reasoning
and subjective judgements. Of course, the potential unreliability of evidence is a problem for any systematic method, or for that matter, for any empirical scientific endeavor at all. Transformed cladistics arose in the late 1970s in an attempt to resolve some of these problems by removing a priori assumptions about phylogeny from cladistic analysis, but it has remained unpopular.


Issues

The cladistic method does not identify fossil species as actual ancestors of a clade. Instead, fossil taxa are identified as belonging to separate extinct branches. While a fossil species could be the actual ancestor of a clade, there is no way to know that. Therefore, a more conservative hypothesis is that the fossil taxon is related to other fossil and extant taxa, as implied by the pattern of shared apomorphic features.


In disciplines other than biology

The comparisons used to acquire data on which
cladograms A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
can be based are not limited to the field of biology. Any group of individuals or classes that are hypothesized to have a common ancestor, and to which a set of common characteristics may or may not apply, can be compared pairwise. Cladograms can be used to depict the hypothetical descent relationships within groups of items in many different academic realms. The only requirement is that the items have characteristics that can be identified and measured.
Anthropology Anthropology is the scientific study of human Humans (''Homo sapiens'') are the most abundant and widespread species In biology Biology is the natural science that studies life and living organisms, including their anatomy, ...
and
archaeology Archaeology or archeology is the study of human activity through the recovery and analysis Analysis is the process of breaking a complexity, complex topic or Substance theory, substance into smaller parts in order to gain a better underst ...
: Cladistic methods have been used to reconstruct the development of cultures or artifacts using groups of cultural traits or artifact features.
Comparative mythology Comparative mythology is the comparison of myth Myth is a folklore genre Folklore is the expressive body of culture shared by a particular group of people; it encompasses the tradition A tradition is a belief A belief is an Attitu ...
and use cladistic methods to reconstruct the protoversion of many myths. Mythological phylogenies constructed with mythemes clearly support low horizontal transmissions (borrowings), historical (sometimes Palaeolithic) diffusions and punctuated evolution. They also are a powerful way to test hypotheses about cross-cultural relationships among folktales.
Literature Literature broadly is any collection of written Writing is a medium of human communication Communication (from Latin ''communicare'', meaning "to share") is the act of developing Semantics, meaning among Subject (philosophy), entitie ...

Literature
: Cladistic methods have been used in the classification of the surviving manuscripts of the ''
Canterbury Tales ''The Canterbury Tales'' ( enm, Tales of Caunterbury) is a collection of 24 stories that runs to over 17,000 lines written in Middle English Middle English (abbreviated to ME) was a form of the English language spoken after the Norman conque ...

Canterbury Tales
'', and the manuscripts of the Sanskrit ''
Charaka Samhita The ''Charaka Saṃhitā'' or ''Compendium of Charaka'' (Sanskrit चरक संहिता IAST: ''caraka-saṃhitā'') is a Sanskrit text on Ayurveda (Indian traditional medicine). Along with the ''Sushruta Samhita, Suśruta-saṃhitā'', it ...
''.
Historical linguistics Historical linguistics, also termed diachronic linguistics, is the scientific study of language change Language change is variation over time in a language A language is a structured system of communication used by humans, including s ...
: Cladistic methods have been used to reconstruct the phylogeny of languages using linguistic features. This is similar to the traditional
comparative method In linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language), gestures (Signed language, sign language) and writing. Most langu ...
of historical linguistics, but is more explicit in its use of parsimony and allows much faster analysis of large datasets (
computational phylogenetics Computational phylogenetics is the application of computational algorithm In and , an algorithm () is a finite sequence of , computer-implementable instructions, typically to solve a class of problems or to perform a computation. Algorithms ...
).
Textual criticism Textual criticism is a branch of textual scholarship, philology, and of literary criticism that is concerned with the identification of textual variants, or different versions, of either manuscripts or of printed books. Such texts may range in da ...
or
stemmatics , Manuscript C, folio 436v, 11th century Textual criticism is a branch of textual scholarship, philology, and of literary criticism that is concerned with the identification of textual variants, or different versions, of either manuscripts or of pr ...
: Cladistic methods have been used to reconstruct the phylogeny of manuscripts of the same work (and reconstruct the lost original) using distinctive copying errors as apomorphies. This differs from traditional historical-comparative linguistics in enabling the editor to evaluate and place in genetic relationship large groups of manuscripts with large numbers of variants that would be impossible to handle manually. It also enables parsimony analysis of contaminated traditions of transmission that would be impossible to evaluate manually in a reasonable period of time.
Astrophysics Astrophysics is a science that employs the methods and principles of physics in the study of astronomical objects and phenomena. Among the subjects studied are the Sun, other stars, galaxy, galaxies, extrasolar planets, the interstellar medium and ...
infers the history of relationships between galaxies to create branching diagram hypotheses of galaxy diversification.


See also

*
Bioinformatics Bioinformatics () is an interdisciplinary field that develops methods and software tools for understanding biology, biological data, in particular when the data sets are large and complex. As an interdisciplinary field of science, bioinformat ...

Bioinformatics
*
Biomathematics Mathematical and theoretical biology or, Biomathematics, is a branch of biology which employs theoretical analysis, mathematical models and abstractions of the Organism, living organisms to investigate the principles that govern the structure, deve ...
*
Coalescent theory Coalescent theory is a model of how gene variants sampled from a population may have originated from a common ancestor. In the simplest case, coalescent theory assumes no recombination, no natural selection, and no gene flow or population structu ...
*
Common descent Common descent is a concept in evolutionary biology Evolutionary biology is the subfield of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chem ...
*
Glossary of scientific naming This is a list of terms and symbols used in scientific names for organisms, and in describing the names. For proper parts of the names themselves, see List of Latin and Greek words commonly used in systematic names. Note that many of the abbreviati ...
*
Language family A language family is a group of language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an apparent answer to the painful divisions b ...
* Patrocladogram *
Phylogenetic network A phylogenetic network is any graph used to visualize evolutionary relationships (either abstractly or explicitly) between nucleotide sequences, gene In biology, a gene (from ''genos'' "...Wilhelm Johannsen coined the word gene to descri ...
*
Scientific classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxon, taxa (singular: ...

Scientific classification
* Stratocladistics *
Subclade In genetics, a subclade is a subgroup of a haplogroup. Naming convention Although human mitochondrial DNA (mtDNA) and Y chromosome DNA (Y-DNA) haplogroups and subclades are named in a similar manner, their names belong to completely separate syste ...
*
Systematics Biological Biology is the natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), o ...
* Three-taxon analysis *
Tree model In historical linguistics Historical linguistics, also termed diachronic linguistics, is the scientific study of language change over time. Principal concerns of historical linguistics include: # to describe and account for observed change ...
*
Tree structure A tree structure, tree diagram, or tree model is a way of representing the hierarchical A hierarchy (from Ancient Greek, Greek: , from , 'president of sacred rites') is an arrangement of items (objects, names, values, categories, etc.) that a ...

Tree structure


Notes and references


Bibliography

* * * * * * * Available free online a
Gallica
(No direct URL). This is the paper credited by for the first use of the term 'clade'. * * * * * * * * * responding to . * Translated from manuscript in German eventually published in 1982 (Phylogenetische Systematik, Verlag Paul Parey, Berlin). * * * * d'Huy, Julien (2012b), "Le motif de Pygmalion : origine afrasienne et diffusion en Afrique". ''Sahara'', 23: 49-5

* d'Huy, Julien (2013a), "Polyphemus (Aa. Th. 1137)." "A phylogenetic reconstruction of a prehistoric tale". ''Nouvelle Mythologie Comparée / New Comparative Mythology'' 1

* * d'Huy, Julien (2013c) "Les mythes évolueraient par ponctuations". ''Mythologie française'', 252, 2013c: 8-12

* d'Huy, Julien (2013d) "A Cosmic Hunt in the Berber sky : a phylogenetic reconstruction of Palaeolithic mythology". ''Les Cahiers de l'AARS'', 15, 2013d: 93-106

* * * * * * * Reissued 1997 in paperback. Includes a reprint of Mayr's 1974 anti-cladistics paper at pp. 433–476, "Cladistic analysis or cladistic classification." This is the paper to which is a response. * * * * . * * * * * * * * Tehrani, Jamshid J., 2013, "The Phylogeny of Little Red Riding Hood", ''PLOS ONE'', 13 Novembe

* * * * *


External links

*
OneZoom: Tree of Life – all living species as intuitive and zoomable fractal explorer (responsive design)

Willi Hennig Society

Cladistics
(scholarly journal of the Willi Hennig Society) * * * * * {{Authority control Phylogenetics Evolutionary biology Zoology Philosophy of biology