Biological classification

science of naming, defining and classifying organisms

thumb|270px|African elephants form the [[genus Loxodonta, a widely accepted taxon.]]

thumb|400px|A comparison of phylogenetic and phenetic (character-based) concepts 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: phylogenetic trees, phylogenies). Phylogenies have two components: branching order (showing group relationships, graphically represented in cladograms) and branch length (showing amount of evolution). Phylogenetic trees of species and higher taxa are used to study the evolution of traits (e.g., anatomical or mol

major work by Carolus Linnaeus

life that exists without a cellular structure, such as virusses, viroids, etc.

closest relative(s) of another given taxon in a phylogenetic tree

Viridiplantae (kingdom Plantae sensu stricto), the green plants, is a natural group or clade of around half a million eukaryotes. They are green because they contain chloroplasts, cell organelles able to produce food by photosynthesis. They are major primary producers of food both in the sea and on land. The group includes both green algae and the land plants (embryophytes) that arose from them.

thumb|right|300px|Two serotypes 1a and 1b with antigens 2a and 2b on surface, which are recognized by two distinct [[antibodies, 3a and 3b, respectively]]

organisation of viruses into a taxonomic system

virus classification system by David Baltimore consisting of 7 groups based on genome type (DNA or RNA), number of strands (single- or double-stranded), sense (positive or negative), and method of replication (through DNA or RNA intermediate)

thumb|A mound built by Nasutitermes triodiae|cathedral termites thumb|A coral colony

gradual variation of the characteristics of a species along its territory

thumb|400px|Nucleotide bonds showing AT and GC pairs. Arrows point to the hydrogen bonds. In molecular biology and genetics, GC-content (or G+C content or guanine-cytosine content) is the percentage of nitrogenous bases in a DNA or RNA molecule that are either guanine (G) or cytosine (C). This measure indicates the proportion of G and C bases out of an implied four total bases, also including adenine and thymine in DNA and adenine and uracil in RNA.

thumb|Wildscreen ARK Launch Party 2024 ARKive was a global initiative with the mission of "promoting the conservation of the world's threatened species, through the power of wildlife imagery", which it did by locating and gathering films, photographs and audio recordings of the world's species into a centralised digital archive. Its priority was the completion of audio-visual profiles for the c. 17,000 species on the IUCN Red List of Threatened Species.

thumb|The ichnogenus Thalassinoides: [[burrow fossil produced by crustaceans from the Middle Jurassic, HaMakhtesh HaKatan, southern Israel]] An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. Ichnotaxon comes from the Ancient Greek (íchnos) meaning "track" and English , itself derived from Ancient Greek (táxis) meaning "ordering".

In biology, phenetics (; ), also known as taximetrics, is an attempt to classify organisms based on overall similarity, usually with respect to morphology or other observable traits, regardless of their phylogeny or evolutionary relation. It is related closely to numerical taxonomy which is concerned with the use of numerical methods for taxonomic classification. Many people contributed to the development of phenetics, but the most influential were Peter Sneath and Robert R. Sokal. Their books are still primary references for this sub-discipline, although now out of print.

branch of biological classification

hypothesis for classification of life

conserved name (a protected scientific name)

name of a taxon, at a rank lower than species

thumb Cormophytes (Cormophyta) is a historical term seldom used today for the plants that are differentiated into roots, stems and leaves. These plants differ from thallophytes, whose body is referred to as the thallus, i.e. a simple body not differentiated into leaves and stems. Definitions have varied, notably about whether mosses and liverworts are included.

thumb|right|Klepton genetic inheritance in frogs In biology, a klepton (abbreviated kl.) and synklepton (abbreviated sk.) is a species that requires input from another biological taxon (normally from a species which is closely related to the kleptonic species) to complete its reproductive cycle. Specific types of kleptons are zygokleptons, which reproduce by zygogenesis; gynokleptons which reproduce by gynogenesis, and tychokleptons, which reproduce by a combination of both systems.

Hypothesis in evolutionary biology

naming system for insect wing veins, devised by John Comstock and George Needham in 1898 and an important step in showing the homology of all insect wings

measure of the cell appearance in tumors and other neoplasms

thumb|Bacterial black spot of mango caused by Xanthomonas citri pv. mangiferaeindicae|Xanthomonas citri pv. mangiferaeindicae A pathovar is a bacterial strain or set of strains with the same or similar characteristics, that is differentiated at infrasubspecific level from other strains of the same species or subspecies on the basis of distinctive pathogenicity to one or more plant hosts. thumb|Bacterial leaf blight of common panax (Polyscias guilfoylei) caused by Xanthomonas campestris pv. hederae Pathovars are named as a ternary or quaternary addition to the species binomial name, for example

classification of organisms based on their morphology

Mythical, magical or otherwise suspect animals mentioned in Systema Naturae

Cormus (Plural|: cormi) (from ancient Greek: κορμός, kormόs, 'stem') is the appearance of a plant that belong to Cormophyte (Pteridophyte and Spermatophyte). In cormus, the vegetative apparatus is no longer a thallus, such as algae, that cannot be distinctly differentiated. The structure of cormus can be easily differentiated into its roots, stems, and leaves.

taxonomic name replacing a preoccupied name

book by Carl Alexander Clerck