Systematics

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Systematics

In its broadest sense, systematics is where nomenclature and taxonomy intersect. Nomenclature is the assignment of accurate names to taxa. Taxonomy refers to the scientific method of classifying and organizing living organisms into specific groups according to their phylogenetic relationships. A single group is called a taxon; multiple groups are called taxa; the study of taxa is called taxonomy. Phylogeny is the study of the evolutionary relationships occurring among living organisms. Classification is the process of putting organisms together into categories based on their relationships to one another.

Carolus Linnaeus (17011778), a Swedish scientist and explorer, is considered the originator of the concept of systematics. He created enormous classifications of plants and animals, and published them as Species Plantarum (1753) and Systema Naturae (tenth edition published in 1758). In the nineteenth century (1800s), those reference volumes were used as the starting point for the modern systems of botanical and zoological nomenclature. One of the reasons that Linnaeuss work was so widely adopted was his use of simple and logical terminology, his hierarchical framework for grouping organisms (That is, a system in which organisms, such as plants or animals, are grouped in progressive order, from lowest to highest. This was generally done from least complex to most complex), and his use of binomial nomenclature, in which two-word names, consisting of a generic name and a descriptor, were created in combinations which were unique to a specific species. His naming system was based on observed physical similarities and differences between organisms; he called these characters.

Systematics has developed into the science both of the diversity of living organisms and of their interrelationships. As conceptualized today, the biological science of phylogenetic systematics seeks to develop novel theories and means for classification that transcend the concepts of taxonomy, and consider not only the similarity of characteristics but also evolutionary processes that result in changes in the original gene pool. The English naturalist Charles Darwin (18091882) was the first scientist to state that systematic hierarchy should reflect similarities and differences in evolutionary history. In the 1950s, a German scientist named Willi Henning suggested the system that has come to be known as phylogenetic systematics; he reasoned that classification of organisms should closely reflect the evolutionary history of specific genetic lines.

On a molecular level and relative to forensic science, every organism has a genome that includes all of the biological materials necessary to replicate itself. The genomes information is encoded in the nucleotide sequence of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) molecules and is subdivided into

units called genes. The Human Genome Project, begun in 1990, was designed to identify each gene in human DNA (estimated to be between 20,000 and 25,000), to classify the sequences of chemical base pairs that make up human DNA (about 3 billion), and to store all of this information in a database. From a forensic science standpoint, the more specifically one can classify living organisms, and the more discretely it is possible to map an individuals DNA, the more accurately it will be possible to match a perpetrator to a crime victim or a crime scene.

See also Deoxyribonucleic acid (DNA); Dna recognition instruments; Forensic science.

Pamela V. Michaels

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Systematics

In its broadest sense, systematics is where nomenclature and taxonomy intersect. Nomenclature is the assignment of accurate names to taxa. A single group is called a taxon; multiple groups are called taxa; the study of taxa is called taxonomy. Taxonomy refers to the scientific method of classifying and organizing living organisms into specific groups according to their phylogenetic relationships. Phylogeny is the study of the evolutionary relationships occurring among living organisms. Classification is the process of putting organisms together into categories based on their relationships to one another.

Carolus Linnaeus (17011778), a Swedish scientist and explorer, is considered the originator of the concept of systematics. He created enormous classifications of plants and animals, and published them as Species Plantarum (1753) and Systema Naturae (tenth edition published in 1758). In the nineteenth century (1800s), those reference volumes were used as the starting point for the modern systems of botanical and zoological nomenclature. One of the reasons that Linnaeus's work was so widely adopted was his use of simple and logical terminology. Another was his hierarchical framework for grouping organisms. (That is, a system in which organisms, such as plants or animals, are grouped in progressive order, from lowest to highest. This was generally done from least complex to most complex.) And finally his use of binomial nomenclature, in which two-word names, consisting of a generic name and a descriptor, were created in combinations which were unique to a specific species. His naming system was based on observed physical similarities and differences between organisms; he called these "characters."

Systematics has developed into the science both of the diversity of living organisms and of their interrelationships. As conceptualized today, the biological science of phylogenetic systematics seeks to develop novel theories and means for classification that transcend the concepts of taxonomy, and consider not only the similarity of characteristics but also evolutionary processes that result in changes in the original gene pool. The English naturalist Charles Darwin (18091882) was the first scientist to state that systematic hierarchy should reflect similarities and differences in evolutionary history. In the 1950s, a German scientist named Willi Henning suggested the system that has come to be known as phylogenetic systematics; he reasoned that classification of organisms should closely reflect the evolutionary history of specific genetic lines.

On a molecular level and relative to forensic science , every organism has a genome that includes all of the biological materials necessary to replicate itself. The genome's information is encoded in the nucleotide sequence of DNA and RNA molecules and is subdivided into units called genes. The Human Genome Project, begun in 1990, was designed to identify each gene in human DNA (estimated to be between 20,000 and 25,000), to classify the sequences of chemical base pairs that make up human DNA (about 3 billion), and to store all of this information in a database. From a forensic science standpoint, the more specifically one can classify living organisms, and the more discretely it is possible to map an individual's DNA, the more accurately it will be possible to match a perpetrator to a crime victim or a crime scene.

see also DNA databanks; DNA sequences, unique; Reference sample.

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systematics The study of the diversity of organisms and their natural relationships. It is sometimes used as a synonym for taxonomy. The term biosystematics (or experimental taxonomy) describes the experimental study of diversity, especially at the species level. Biosystematic methods include breeding experiments, field work, biochemical work (known as chemosystematics), and cytotaxonomy. See also molecular systematics.

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sys·tem·at·ics / ˌsistəˈmatiks/ • pl. n. [treated as sing.] the branch of biology that deals with classification and nomenclature; taxonomy.