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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), organizes knowl ...

Biological
systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms:
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 ...
,
phylogenetic tree A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree (graph theory), tree showing the evolutionary relationships among va ...

phylogenetic tree
s, phylogenies). Phylogenies have two components: branching order (showing group relationships) and branch length (showing amount of evolution). Phylogenetic trees of species and higher
taxa 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 ...
are used to study the evolution of traits (e.g., anatomical or molecular characteristics) and the distribution of organisms (
biogeography Biogeography is the study of the distribution of species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defin ...

biogeography
). Systematics, in other words, is used to understand the evolutionary history of life on Earth. The word systematics is derived from Latin word `systema', which means systematic arrangement of organisms.
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomi ...

Carl Linnaeus
used '
Systema Naturae ' (originally in Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic ...
' as the title of his book.


Branches and applications

In the study of biological systematics, researchers use the different branches to further understand the relationships between differing organisms. These branches are used to determine the applications and uses for modern day systematics. Biological systematics classifies species by using three specific branches. ''Numerical systematics'', or ''biometry'', uses biological statistics to identify and classify animals. ''Biochemical systematics'' classifies and identifies animals based on the analysis of the material that makes up the living part of a cell—such as the
nucleus ''Nucleus'' (plural nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA ...

nucleus
,
organelle In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, ...
s, and
cytoplasm In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...
. ''Experimental systematics'' identifies and classifies animals based on the evolutionary units that comprise a species, as well as their importance in evolution itself. Factors such as mutations, genetic divergence, and hybridization all are considered evolutionary units. With the specific branches, researchers are able to determine the applications and uses for modern-day systematics. These applications include: * Studying the diversity of organisms and the differentiation between extinct and living creatures. Biologists study the well-understood relationships by making many different diagrams and "trees" (cladograms, phylogenetic trees, phylogenies, etc.). * Including the scientific names of organisms, species descriptions and overviews, taxonomic orders, and classifications of evolutionary and organism histories. * Explaining the biodiversity of the planet and its organisms. The systematic study is that of conservation. * Manipulating and controlling the natural world. This includes the practice of 'biological control', the intentional introduction of natural predators and disease.


Definition and relation with taxonomy

John Lindley John Lindley Fellow of the Royal Society, FRS (5 February 1799 – 1 November 1865) was an England, English botanist, gardener and orchidology, orchidologist. Early years Born in Old Catton, Catton, near Norwich, England, John Lindley was one of ...

John Lindley
provided an early definition of systematics in 1830, although he wrote of "systematic botany" rather than using the term "systematics". In 1970 Michener ''et al.'' defined "systematic biology" and "
taxonomy Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally used only about biological ...
" (terms that are often confused and used interchangeably) in relationship to one another as follows:
Systematic biology (hereafter called simply systematics) is the field that (a) provides scientific names for organisms, (b) describes them, (c) preserves collections of them, (d) provides classifications for the organisms, keys for their identification, and data on their distributions, (e) investigates their evolutionary histories, and (f) considers their environmental adaptations. This is a field with a long history that in recent years has experienced a notable renaissance, principally with respect to theoretical content. Part of the theoretical material has to do with evolutionary areas (topics e and f above), the rest relates especially to the problem of classification. Taxonomy is that part of Systematics concerned with topics (a) to (d) above.
The term "taxonomy" was coined by
Augustin Pyramus de Candolle Augustin Pyramus (or Pyrame) de Candolle (, , ; 4 February 17789 September 1841) was a Swiss people, Swiss botany, botanist. René Louiche Desfontaines launched de Candolle's botanical career by recommending him at an herbarium. Within a couple ...
while the term "systematic" was coined by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomi ...

Carl Linnaeus
the father of taxonomy. Taxonomy, systematic biology, systematics, biosystematics, scientific classification, biological classification, phylogenetics: At various times in history, all these words have had overlapping, related meanings. However, in modern usage, they can all be considered synonyms of each other. For example, Webster's 9th New Collegiate Dictionary of 1987 treats "classification", "taxonomy", and "systematics" as synonyms. According to this work, the terms originated in 1790, c. 1828, and in 1888 respectively. Some claim systematics alone deals specifically with relationships through time, and that it can be synonymous with
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
, broadly dealing with the inferred hierarchy of organisms. This means it would be a subset of taxonomy as it is sometimes regarded, but the inverse is claimed by others. Europeans tend to use the terms "systematics" and "biosystematics" for the study of biodiversity as a whole, whereas North Americans tend to use "taxonomy" more frequently. However, taxonomy, and in particular
alpha taxonomy 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: ...
, is more specifically the identification, description, and naming (i.e. nomenclature) of organisms, while "classification" focuses on placing organisms within hierarchical groups that show their relationships to other organisms. All of these biological disciplines can deal with both
extinct Extinction is the termination of a kind of organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by ...
and
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 species. The moment of extinction is generally considered to be the death of the endling, last individual o ...
organisms. Systematics uses taxonomy as a primary tool in understanding, as nothing about an organism's relationships with other living things can be understood without it first being properly studied and described in sufficient detail to identify and classify it correctly. Scientific classifications are aids in recording and reporting information to other scientists and to laymen. The systematist, a scientist who specializes in systematics, must, therefore, be able to use existing classification systems, or at least know them well enough to skilfully justify not using them.
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 ...
was an attempt to determine the relationships of organisms through a measure of overall similarity, making no distinction between
plesiomorph File:Cladogram imaginary birds.jpg, Imaginary cladogram. The yellow mask is a plesiomorphy for each living masked species, because it is ancestral. It is also a symplesiomorphy for them. But for the four living species as a whole, it is an apomorph ...
ies (shared ancestral traits) and
apomorph 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 ...
ies (derived traits). From the late-20th century onwards, it was superseded by
cladistics Cladistics (; ) is an approach to biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying groups of biological organisms based on shared ch ...

cladistics
, which rejects plesiomorphies in attempting to resolve the
phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree (graph theory), tree showing the evolutionary relationships among va ...

phylogeny
of Earth's various organisms through time. systematists generally make extensive use of
molecular biology Molecular biology is the branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, molecular synthesis, modification, mechanisms, and interaction ...
and of
computer programs A computer program is a collection of instructions that can be executed by a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform ...
to study organisms.


Taxonomic characters

Taxonomic characters are the taxonomic attributes that can be used to provide the evidence from which relationships (the
phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree (graph theory), tree showing the evolutionary relationships among va ...

phylogeny
) between taxa are inferred. Kinds of taxonomic characters include:Mayr, Ernst (1991), p. 162. * Morphological characters ** General external morphology ** Special structures (e.g. genitalia) ** Internal morphology (anatomy) ** Embryology ** Karyology and other cytological factors * Physiological characters ** Metabolic factors ** Body secretions ** Genic sterility factors * Molecular characters ** Immunological distance ** Electrophoretic differences ** Amino acid sequences of proteins ** DNA hybridization ** DNA and RNA sequences ** Restriction endonuclease analyses ** Other molecular differences * Behavioral characters ** Courtship and other ethological isolating mechanisms ** Other behavior patterns * Ecological characters ** Habit and habitats ** Food ** Seasonal variations ** Parasites and hosts * Geographic characters ** General biogeographic distribution patterns ** Sympatric-allopatric relationship of populations


See also

*
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 ...
*
Cladistics Cladistics (; ) is an approach to biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying groups of biological organisms based on shared ch ...

Cladistics
– a
methodology Methodology is the study of research methods, or, more formally, "'a contextual framework' for research, a coherent and logical scheme based on views, beliefs, and values, that guides the choices researchers
r other users R, or r, is the eighteenth letter of the modern English alphabet and the ISO basic Latin alphabet The ISO basic Latin alphabet is a Latin-script alphabet A Latin-script alphabet (Latin alphabet or Roman alphabet) is an alphabet that ...
make". It compris ...
in systematics *
Evolutionary systematics Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physica ...
– a school of systematics *
Global biodiversity Global biodiversity is the measure of biodiversity on planet Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land consisting of continent A conti ...
*
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 ...
– a methodology in systematics that does not infer phylogeny *
Phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree (graph theory), tree showing the evolutionary relationships among va ...

Phylogeny
– the historical relationships between lineages of organism *
16S ribosomal RNA 16 S ribosomal RNA (or 16 S rRNA Ribosomal ribonucleic acid (rRNA) is a type of which is the primary component of s, essential to all cells. rRNA is a which carries out in ribosomes. Ribosomal RNA is transcribed from (rDNA) and then ...
– an intensively studied nucleic acid that has been useful in phylogenetics *
Phylogenetic comparative methods Phylogenetic comparative methods (PCMs) use information on the historical relationships of lineages ( phylogenies) to test evolutionary hypotheses. The comparative method has a long history in evolutionary biology; indeed, Charles Darwin C ...
– use of evolutionary trees in other studies, such as
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
, comparative biology. adaptation, or evolutionary mechanisms *
Scientific 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 ...

Scientific classification
and
Taxonomy Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally used only about biological ...
– the result of research in systematics


References


Notes


Further reading

* Schuh, Randall T. and Andrew V. Z. Brower. 2009. ''Biological Systematics: Principles and Applications, 2nd edn.'' * Simpson, Michael G. 2005. ''Plant Systematics''. * Wiley, Edward O. and Bruce S. Lieberman. 2011. "Phylogenetics: Theory and Practice of Phylogenetic Systematics, 2nd edn."


External links


Society of Australian Systematic Biologists

Society of Systematic Biologists

The Willi Hennig Society
{{Authority control Evolutionary biology Biological classification