Biological classification in the context of "Order (biology)"

Genus (/ˈdʒiːnəs/; pl.: genera /ˈdʒɛnərə/) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful:

Zoology (/zoʊˈɒlədʒi/ zoh-OL-ə-jee, UK also /zuˈ-/ zoo-) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one of the primary branches of biology. The term is derived from Ancient Greek ζῷον, zōion ('animal'), and λόγος, logos ('knowledge', 'study').

Although humans have always been interested in the natural history of the animals they saw around them, and used this knowledge to domesticate certain species, the formal study of zoology can be said to have originated with Aristotle. He viewed animals as living organisms, studied their structure and development, and considered their adaptations to their surroundings and the function of their parts. Modern zoology has its origins during the Renaissance and early modern period, with Carl Linnaeus, Antonie van Leeuwenhoek, Robert Hooke, Charles Darwin, Gregor Mendel and many others.

In biological classification, a subfamily (Latin: subfamilia, plural subfamiliae) is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zoological subfamily names with "-inae".

Detarioideae is an example of a botanical subfamily. Detarioideae is a subdivision of the family Fabaceae (legumes), containing 84 genera.

The history of plant systematics—the biological classification of plants—stretches from the work of ancient Greek to modern evolutionary biologists. As a field of science, plant systematics came into being only slowly, early plant lore usually being treated as part of the study of medicine. Later, classification and description was driven by natural history and natural theology. Until the advent of the theory of evolution, nearly all classification was based on the scala naturae. The professionalization of botany in the 18th and 19th century marked a shift toward more holistic classification methods, eventually based on evolutionary relationships.

Hildegardia is a genus of trees in the family Malvaceae. The genus includes 12 species with a pantropical distribution.

In older systems of classification, it was placed in Sterculiaceae, but all members of that family are now in an expanded Malvaceae. The genus is named for Saint Hildegard of Bingen due to her contributions to herbal medicine.

The two-domain system is a biological classification of all organisms in the tree of life into two domains: Archaea, which includes eukaryotes in this classification, and Bacteria. It emerged from development of knowledge of archaea diversity and challenges the widely accepted three-domain system that classifies life into Bacteria, Archaea, and Eukarya. It was preceded by the eocyte hypothesis of James A. Lake in the 1980s, which was largely superseded by the three-domain system, due to evidence at the time. Better understanding of archaea, especially of their roles in the origin of eukaryotes through symbiogenesis with bacteria, led to the revival of the eocyte hypothesis in the 2000s. The two-domain system became more widely accepted after the discovery of a large kingdom of archaea called Promethearchaeati in 2017, which evidence suggests to be the evolutionary root of eukaryotes, thereby making eukaryotes members of the domain Archaea.

While the features of promethearchaea do not completely rule out the three-domain system, the notion that eukaryotes originated within Archaea has been strengthened by genetic and proteomic studies. Under the three-domain system, Eukarya is mainly distinguished by the presence of "eukaryotic signature proteins" that are not found in Archaea and Bacteria. However, promethearchaea contain genes that code for multiple such proteins.

In biological taxonomy, circumscription is the content of a taxon, that is, the delimitation of which subordinate taxa are parts of that taxon. For example, if it is determined that species X, Y, and Z belong in genus A, and species T, U, V, and W belong in genus B, those are the circumscriptions of those two genera. Another systematist might determine that T, U, V, W, X, Y, and Z all belong in genus A. Agreement on circumscriptions is not governed by the codes of zoological or botanical nomenclature, and must be reached by scientific consensus.

A goal of biological taxonomy is to achieve a stable circumscription for every taxon. This goal conflicts, at times, with the goal of achieving a natural classification that reflects the evolutionary history of divergence of groups of organisms. Balancing these two goals is a work in progress, and the circumscriptions of many taxa that had been regarded as stable for decades are in upheaval in the light of rapid developments in molecular phylogenetics. New evidence may suggest that a traditional circumscription should be revised, particularly if the old circumscription is shown to be paraphyletic (a group containing some but not all of the descendants of the common ancestor).