Taxon in the context of "Node-based taxon"

Brain–body mass ratio, also known as the brain–body weight ratio, is the ratio of brain mass to body mass, which is hypothesized to be a rough estimate of the intelligence of an animal, although fairly inaccurate in many cases. A more complex measurement, encephalization quotient, takes into account allometric effects of widely divergent body sizes across several taxa. The raw brain-to-body mass ratio is however simpler to come by, and is still a useful tool for comparing encephalization within species or between fairly closely related species.

Biodiversity is the variability of life on Earth. It can be measured on various levels, for example, genetic variability, species diversity, ecosystem diversity and phylogenetic diversity. Diversity is not distributed evenly on Earth—it is greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than one-fifth of Earth's terrestrial area and contain about 50% of the world's species. There are latitudinal gradients in species diversity for both marine and terrestrial taxa.

Since life began on Earth, six major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic aeon (the last 540 million years) marked a rapid growth in biodiversity via the Cambrian explosion. In this period, the majority of multicellular phyla first appeared. The next 400 million years included repeated, massive biodiversity losses. Those events have been classified as mass extinction events. In the Carboniferous, rainforest collapse may have led to a great loss of plant and animal life. The Permian–Triassic extinction event, 251 million years ago, was the worst; vertebrate recovery took 30 million years.

This list of Latin and Greek words commonly used in systematic names is intended to help those unfamiliar with classical languages to understand and remember the scientific names of organisms. The binomial nomenclature used for animals and plants is largely derived from Latin and Greek words, as are some of the names used for higher taxa, such as orders and above. At the time when biologist Carl Linnaeus (1707–1778) published the books that are now accepted as the starting point of binomial nomenclature, Latin was used in Western Europe as the common language of science, and scientific names were in Latin or Greek: Linnaeus continued this practice.

While learning Latin is now less common, it is still used by classical scholars, and for certain purposes in botany, medicine and the Roman Catholic Church, and it can still be found in scientific names. It is helpful to be able to understand the source of scientific names. Although the Latin names do not always correspond to the current English common names, they are often related, and if their meanings are understood, they are easier to recall. The binomial name often reflects limited knowledge or hearsay about a species at the time it was named. For instance Pan troglodytes, the chimpanzee, and Troglodytes troglodytes, the wren, are not necessarily cave-dwellers.

A protist (/ˈproʊtɪst/ PROH-tist) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancestor excluding land plants, animals, and fungi.

Protists were historically regarded as a separate taxonomic kingdom known as Protista or Protoctista. With the advent of phylogenetic analysis and electron microscopy studies, the use of Protista as a formal taxon was gradually abandoned. In modern classifications, protists are spread across several eukaryotic clades called supergroups, such as Archaeplastida (photoautotrophs that includes land plants), SAR, Obazoa (which includes fungi and animals), Amoebozoa and "Excavata".

Species distribution, or species dispersion, is the manner in which a biological taxon is spatially arranged. The geographic limits of a particular taxon's distribution is its range, often represented as shaded areas on a map. Patterns of distribution change depending on the scale at which they are viewed, from the arrangement of individuals within a small family unit, to patterns within a population, or the distribution of the entire species as a whole (range). Species distribution is not to be confused with dispersal, which is the movement of individuals away from their region of origin or from a population center of high density.

In biology, taxonomy (from Ancient Greek τάξις (taxis) 'arrangement' and -νομία (-nomia) 'method') is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon), and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (division is sometimes used in botany in place of phylum), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, having developed a ranked system known as Linnaean taxonomy for categorizing organisms.

With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the evolutionary relationships among organisms, both living and extinct.

Cuckoos are birds in the Cuculidae (/kjuːˈkjuːlɪdiː/ kew-KEW-lih-dee) family, the sole taxon in the order Cuculiformes (/kjuːˈkjuːlɪfɔːrmiːz/ kew-KEW-lih-for-meez). The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals, and anis. The coucals and anis are sometimes separated as distinct families, the Centropodidae and Crotophagidae, respectively. The cuckoo order Cuculiformes is one of three that make up the Otidimorphae, the other two being the turacos and the bustards. The family Cuculidae contains 150 species, which are divided into 33 genera.

The cuckoos are generally medium-sized, slender birds. Most species live in trees, though a sizeable minority are ground-dwelling. The family has a cosmopolitan distribution; the majority of species are tropical. Some species are migratory. The cuckoos feed on insects, insect larvae, and a variety of other animals, as well as fruit. Some species (for example, the majority of cuckoo species living in Eurasia) are brood parasites, laying their eggs in the nests of other species and giving rise to the terms "cuckoo's egg" and "cuckold" as metaphors. However, most species raise their own young.

Vegetation is an assemblage of plants and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader than the term flora which refers to species composition. Perhaps the closest synonym is plant community, but "vegetation" can, and often does, refer to a wider range of spatial scales than that term does, including scales as large as the global. Primeval redwood forests, coastal mangrove stands, sphagnum bogs, desert soil crusts, roadside weed patches, wheat fields, cultivated gardens and lawns; all are encompassed by the term "vegetation".

The vegetation type is defined by characteristic dominant species, or a common aspect of the assemblage, such as an elevation range or environmental commonality. The contemporary use of "vegetation" approximates that of ecologist Frederic Clements' term earth cover, an expression still used by the Bureau of Land Management.

The International Code of Nomenclature for Cultivated Plants (ICNCP) is a guide to the rules and regulations for naming cultigens, plants whose origin or selection is primarily due to intentional human activity. It is also known as Cultivated Plant Code. Cultigens under the purview of the ICNCP include cultivars, Groups (cultivar groups), and grexes. All organisms traditionally considered to be plants (including algae and fungi) are included. Taxa that receive a name under the ICNCP will also be included within taxa named under the International Code of Nomenclature for algae, fungi, and plants, for example, a cultivar is a member of a species.

Cyanobacteria (/saɪˌænoʊbækˈtɪəriə/ sy-AN-oh-bak-TEER-ee-ə) are a group of autotrophic gram-negative bacteria of the phylum Cyanobacteriota that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" (from Ancient Greek κύανος (kúanos) 'blue') refers to their bluish green (cyan) color, which forms the basis of cyanobacteria's informal common name, blue-green algae.

Cyanobacteria are probably the most numerous taxon to have ever existed on Earth and the first organisms known to have produced oxygen, having appeared in the middle Archean eon and apparently originated in a freshwater or terrestrial environment. Their photopigments can absorb the red- and blue-spectrum frequencies of sunlight (thus reflecting a greenish color) to split water molecules into hydrogen ions and oxygen. The hydrogen ions are used to react with carbon dioxide to produce complex organic compounds such as carbohydrates (a process known as carbon fixation), and the oxygen is released as a byproduct. By continuously producing and releasing oxygen over billions of years, cyanobacteria are thought to have converted the early Earth's anoxic, weakly reducing prebiotic atmosphere, into an oxidizing one with free gaseous oxygen (which previously would have been immediately removed by various surface reductants), resulting in the Great Oxidation Event and the "rusting of the Earth" during the early Proterozoic, dramatically changing the composition of life forms on Earth. The subsequent adaptation of early single-celled organisms to survive in oxygenous environments likely led to endosymbiosis between anaerobes and aerobes, and hence the evolution of eukaryotes during the Paleoproterozoic.

In biological taxonomy, taxonomic rank (which some authors prefer to call nomenclatural rank because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of organisms (a taxon) in a hierarchy that reflects evolutionary relationships. Thus, the most inclusive clades (such as Eukarya and Animalia) have the highest ranks, whereas the least inclusive ones (such as Homo sapiens or Bufo bufo) have the lowest ranks. Ranks can be either relative and be denoted by an indented taxonomy in which the level of indentation reflects the rank, or absolute, in which various terms, such as species, genus, family, order, class, phylum, kingdom, and domain designate rank. This page emphasizes absolute ranks and the rank-based codes (the Zoological Code, the Botanical Code, the Code for Cultivated Plants, the Prokaryotic Code, and the Code for Viruses) require them. However, absolute ranks are not required in all nomenclatural systems for taxonomists; for instance, the PhyloCode, the code of phylogenetic nomenclature, does not require absolute ranks.

Taxa are hierarchical groups of organisms, and their ranks describes their position in this hierarchy. High-ranking taxa (e.g. those considered to be domains or kingdoms, for instance) include more sub-taxa than low-ranking taxa (e.g. those considered genera, species or subspecies). The rank of these taxa reflects inheritance of traits or molecular features from common ancestors. The name of any species and genus are basic; which means that to identify a particular organism, it is usually not necessary to specify names at ranks other than these first two, within a set of taxa covered by a given rank-based code. However, this is not true globally because most rank-based codes are independent from each other, so there are many inter-code homonyms (the same name used for different organisms, often for an animal and for a taxon covered by the botanical code). For this reason, attempts were made at creating a BioCode that would regulate all taxon names, but this attempt has so far failed because of firmly entrenched traditions in each community.

In biology, morphology is the study of the form and structure of organisms and their specific structural features.

This includes aspects of the outward appearance (shape, structure, color, pattern, size), as well as the form and structure of internal parts like bones and organs, i.e., anatomy. This is in contrast to physiology, which deals primarily with function. Morphology is a branch of life science dealing with the study of the overall structure of an organism or taxon and its component parts.

Extinction is the termination of an organism by the death of its last member. A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover. As a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence.

Over five billion species are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryotes globally, possibly many times more if microorganisms are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, and mammoths. Through evolution, species arise through the process of speciation. Species become extinct when they are no longer able to survive in changing conditions or against superior competition. The relationship between animals and their ecological niches has been firmly established. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive with little to no morphological change for hundreds of millions of years, though this claim has been disputed.

In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and environmental conditions, though this is not always so. Killer whales (orcas) are among the most well-known cosmopolitan species on the planet, as they maintain several different resident and transient populations in every major oceanic body on Earth, from the Arctic Circle to Antarctica and every coastal and open-water region in-between. Such a taxon (usually a species) is said to have a cosmopolitan distribution, or exhibit cosmopolitanism, as a species; another example, the rock dove (commonly referred to as a 'pigeon'), in addition to having been bred domestically for centuries, now occurs in most urban areas around the world.

The extreme opposite of a cosmopolitan species is an endemic (native) species, or one found only in a single geographical location. Endemism usually results in organisms with specific adaptations to one particular climate or region, and the species would likely face challenges if placed in a different environment. There are far more examples of endemic species than cosmopolitan species; one example being the snow leopard, a species found only in Central Asian mountain ranges, an environment to which the cats have adapted over millions of years.

In botany, an infraspecific name is the scientific name for any taxon below the rank of species, i.e. an infraspecific taxon or infraspecies. The scientific names of botanical taxa are regulated by the International Code of Nomenclature for algae, fungi, and plants (ICN). As specified by the ICN, the name of an infraspecific taxon is a combination of the name of a species and an infraspecific epithet, separated by a connecting term that denotes the rank of the taxon. An example of an infraspecific name is Astrophytum myriostigma subvar. glabrum, the name of a subvariety of the species Astrophytum myriostigma (bishop's hat cactus). In the previous example, glabrum is the infraspecific epithet.

Names below the rank of species of animals and of cultivated plants are regulated by different codes of nomenclature and are formed somewhat differently.

The International Code of Nomenclature of Prokaryotes (ICNP) or Prokaryotic Code, formerly the International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC), governs the scientific names for Bacteria and Archaea. It denotes the rules for naming taxa of bacteria, according to their relative rank. As such it is one of the nomenclature codes of biology.

Originally the International Code of Botanical Nomenclature dealt with bacteria, and this kept references to bacteria until these were eliminated at the 1975 International Botanical Congress. An early Code for the nomenclature of bacteria was approved at the 4th International Congress for Microbiology in 1947, but was later discarded.

In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes the defining features of that particular taxon. In older usage (pre-1900 in botany), a type was a taxon rather than a specimen.

A taxon is a scientifically named grouping of organisms with other like organisms, a set that includes some organisms and excludes others, based on a detailed published description (for example a species description) and on the provision of type material, which is usually available to scientists for examination in a major museum research collection, or similar institution.