Evolutionary taxonomy

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Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of phylogenetic relationship (shared descent), progenitor-descendant relationship (serial descent), and degree of evolutionary change. Evolutionary taxonomy_sentence_0

This type of taxonomy may consider whole taxa rather than single species, so that groups of species can be inferred as giving rise to new groups. Evolutionary taxonomy_sentence_1

The concept found its most well-known form in the modern evolutionary synthesis of the early 1940s. Evolutionary taxonomy_sentence_2

Evolutionary taxonomy differs from strict pre-Darwinian Linnaean taxonomy (producing orderly lists only), in that it builds evolutionary trees. Evolutionary taxonomy_sentence_3

While in phylogenetic nomenclature each taxon must consist of a single ancestral node and all its descendants, evolutionary taxonomy allows for groups to be excluded from their parent taxa (e.g. dinosaurs are not considered to include birds, but to have given rise to them), thus permitting paraphyletic taxa. Evolutionary taxonomy_sentence_4

Origin of evolutionary taxonomy Evolutionary taxonomy_section_0

Evolutionary taxonomy arose as a result of the influence of the theory of evolution on Linnaean taxonomy. Evolutionary taxonomy_sentence_5

The idea of translating Linnaean taxonomy into a sort of dendrogram of the Animal and Plant Kingdoms was formulated toward the end of the 18th century, well before Charles Darwin's book On the Origin of Species was published. Evolutionary taxonomy_sentence_6

The first to suggest that organisms had common descent was Pierre-Louis Moreau de Maupertuis in his 1751 Essai de Cosmologie, Transmutation of species entered wider scientific circles with Erasmus Darwin's 1796 Zoönomia and Jean-Baptiste Lamarck's 1809 Philosophie Zoologique. Evolutionary taxonomy_sentence_7

The idea was popularised in the English-speaking world by the speculative but widely read Vestiges of the Natural History of Creation, published anonymously by Robert Chambers in 1844. Evolutionary taxonomy_sentence_8

Following the appearance of On the Origin of Species, Tree of Life representations became popular in scientific works. Evolutionary taxonomy_sentence_9

In On the Origin of Species, the ancestor remained largely a hypothetical species; Darwin was primarily occupied with showing the principle, carefully refraining from speculating on relationships between living or fossil organisms and using theoretical examples only. Evolutionary taxonomy_sentence_10

In contrast, Chambers had proposed specific hypotheses, the evolution of placental mammals from marsupials, for example. Evolutionary taxonomy_sentence_11

Following Darwin's publication, Thomas Henry Huxley used the fossils of Archaeopteryx and Hesperornis to argue that the birds are descendants of the dinosaurs. Evolutionary taxonomy_sentence_12

Thus, a group of extant animals could be tied to a fossil group. Evolutionary taxonomy_sentence_13

The resulting description, that of dinosaurs "giving rise to" or being "the ancestors of" birds, exhibits the essential hallmark of evolutionary taxonomic thinking. Evolutionary taxonomy_sentence_14

The past three decades have seen a dramatic increase in the use of DNA sequences for reconstructing phylogeny and a parallel shift in emphasis from evolutionary taxonomy towards Hennig's 'phylogenetic systematics'. Evolutionary taxonomy_sentence_15

Today, with the advent of modern genomics, scientists in every branch of biology make use of molecular phylogeny to guide their research. Evolutionary taxonomy_sentence_16

One common method is multiple sequence alignment. Evolutionary taxonomy_sentence_17

Cavalier-Smith, G. Evolutionary taxonomy_sentence_18 G. Simpson and Ernst Mayr are some representative evolutionary taxonomists. Evolutionary taxonomy_sentence_19

New methods in modern evolutionary systematics Evolutionary taxonomy_section_1

The Tree of Life Evolutionary taxonomy_section_2

Main article: Tree of life (biology) Evolutionary taxonomy_sentence_20

As more and more fossil groups were found and recognized in the late 19th and early 20th century, palaeontologists worked to understand the history of animals through the ages by linking together known groups. Evolutionary taxonomy_sentence_21

The Tree of life was slowly being mapped out, with fossil groups taking up their position in the tree as understanding increased. Evolutionary taxonomy_sentence_22

These groups still retained their formal Linnaean taxonomic ranks. Evolutionary taxonomy_sentence_23

Some of them are paraphyletic in that, although every organism in the group is linked to a common ancestor by an unbroken chain of intermediate ancestors within the group, some other descendants of that ancestor lie outside the group. Evolutionary taxonomy_sentence_24

The evolution and distribution of the various taxa through time is commonly shown as a spindle diagram (often called a Romerogram after the American palaeontologist Alfred Romer) where various spindles branch off from each other, with each spindle representing a taxon. Evolutionary taxonomy_sentence_25

The width of the spindles are meant to imply the abundance (often number of families) plotted against time. Evolutionary taxonomy_sentence_26

Vertebrate palaeontology had mapped out the evolutionary sequence of vertebrates as currently understood fairly well by the closing of the 19th century, followed by a reasonable understanding of the evolutionary sequence of the plant kingdom by the early 20th century. Evolutionary taxonomy_sentence_27

The tying together of the various trees into a grand Tree of Life only really became possible with advancements in microbiology and biochemistry in the period between the World Wars. Evolutionary taxonomy_sentence_28

Terminological difference Evolutionary taxonomy_section_3

The two approaches, evolutionary taxonomy and the phylogenetic systematics derived from Willi Hennig, differ in the use of the word "monophyletic". Evolutionary taxonomy_sentence_29

For evolutionary systematicists, "monophyletic" means only that a group is derived from a single common ancestor. Evolutionary taxonomy_sentence_30

In phylogenetic nomenclature, there is an added caveat that the ancestral species and all descendants should be included in the group. Evolutionary taxonomy_sentence_31

The term "holophyletic" has been proposed for the latter meaning. Evolutionary taxonomy_sentence_32

As an example, amphibians are monophyletic under evolutionary taxonomy, since they have arisen from fishes only once. Evolutionary taxonomy_sentence_33

Under phylogenetic taxonomy, amphibians do not constitute a monophyletic group in that the amniotes (reptiles, birds and mammals) have evolved from an amphibian ancestor and yet are not considered amphibians. Evolutionary taxonomy_sentence_34

Such paraphyletic groups are rejected in phylogenetic nomenclature, but are considered a signal of serial descent by evolutionary taxonomists. Evolutionary taxonomy_sentence_35

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Evolutionary taxonomy.