What is Genus?

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Genus Definition Biology: Genus (plural genera) is a taxonomic rank in biology that is used to classify living and extinct species, and also viruses. Genus is placed over species and below family throughout the biological classification hierarchy. The genus-species name is the first element of the binomial species name for every species belonging to the genus in binomial nomenclature.

Genus Example: Panthera leo (lion) and Panthera onca (jaguar), for example, are two species in the Panthera genus. Panthera has become a genus of the Felidae family. This genus example gives us the perfect description of the question of what is genus in Biology?. 

Genus and Species Definition and Classification

Taxonomists decide the makeup of a genus. Since there are no definite codified criteria for genus classification, various authorities frequently create different classifications for genera.

However, there are some common practises, such as the suggestion that a newly identified genus should meet these three conditions in order to be concisely beneficial:

  • Monophyly - All descendants of an ancestral taxon were placed together in monophyly (that is, a phylogenetic analysis must specifically clearly demonstrate both monophyly and validity as a separate lineage).

  • Fair Compactness – A genus must not be overly extended.

  • Distinctness – In terms of evolutionarily applicable parameters such as ecology, anatomy, or biogeography; DNA sequences are a result instead of a cause of diverging evolutionary lineages unless they specifically impede gene flow (for example, postzygotic barriers).

Furthermore, genera should be made up of the very same phylogenetic units as other (analogous) genera.


The generic name of the genus is sometimes known as its scientific name (or scientific epithet); it is often capitalised in modern style science and guides. It is used in binomial nomenclature, a method for labelling organisms, in which it is associated with an organism' scientific name: see Specific name (zoology) and Specific name (Botany).

Use in Nomenclature:

The guidelines for scientific names of species are set out in the Nomenclature Codes, which enable every species to have a single specific name which is Latin and binomial in type for "plants," "animals," and prokaryotes (Archaea and Bacteria); this contrasts towards popular or vernacular names, which have been non-standardized, may be non-unique, and sometimes differ by country and language of use. The standard format for a species name, with the exception of viruses, is the generic name, which indicates the genus under which the species relates, accompanied by the particular epithet, that is exclusive to the organism within the same genus.

Canis lupus, for instance, is the scientific name for the grey wolf, and with Canis (Latin for "dog") as the generic name used by the wolf's immediate relatives and lupus (Latin for "wolf") as the specific name exclusive to the wolf. Hibiscus arnottianus, a species of the genus Hibiscus native to Hawaii, is a botanical reference. In zoology and botany, the basic names are listed in lower case and might even be accompanied by subspecies names or a number of infraspecific names.

The Type Concept: 

Each genus should get its own type, however, there is a backlog of older names that do not have one. It is the kind species in zoology, and the common name is often linked to the type specimen of the type species. If the species is assigned to a different genus, the generic name associated with it becomes a junior synonym, and the residual taxa in the former genus must be reevaluated.

Categories of Generic Name:

Taxonomic names, along with those of genera, are listed as "available" or "unavailable" in zoological terminology. Appropriate names are those that have been reported in compliance with the International Code of Zoological Nomenclature (ICZN) and have not been prohibited by subsequent decisions of the ICZN; the latest known term for any taxon (for instance, a genus) should therefore be chosen as the "true" (— for example, existing or acknowledged) title for the taxon in question.

Identical Names (homonyms):

A generic name could only refer to one genus in the same kingdom. Most names, on the other hand, are being mistakenly identified by two or even more genera. The platypus, for instance, belongs to the genus Ornithorhynchus, despite the fact that George Shaw labelled it Platypus in 1799. Johann Friedrich Wilhelm Herbst had already assigned the term Platypus to a group of ambrosia beetles in 1793. A homonym is a term that has two different meanings. The name should not be preferred for all beetles and platypuses since they are both parts of the Animalia kingdom. In 1800, Johann Friedrich Blumenbach published Ornithorhynchus as a replacement phrase.

Use in Higher Classifications:

The basic genus serves as the foundation for higher taxonomic levels, including the Canidae ("Canids") family name. Nevertheless, this usually only goes up one or two stages: Carnivora seems to be the order in which dogs and wolves belong ("Carnivores").

Numbers of Accepted Genera:

The precise figure of approved or all reported genus names is unknown; Rees et al., 2020 predict that there are nearly 310,000 accepted names (valid taxa) out of a total of c. As of the end of 2019, there were 520,000 recorded names (such as synonyms), with 2,500 new generic names being added per year.

Genus Size

The list of genus biology examples in a given genus varies greatly between taxonomic groups. For example, among the 1180 genera of non-avian reptiles, the majority (>300) have only one species, approximately 360 possess between two and four species, 260 have five to ten species, 200 have eleven to fifty species, and only 27 genera carry more than fifty species. However, several insect genera include over 1000 species, including the bee genera Lasioglossum and Andrena. Astragalus is the greatest flowering plant genus, with over 3,000 species.

The assignment of species to a genus is rather subjective. There are no specific standards for organizing species into genera, despite the fact that all species within a genus are expected to be "similar." Wide, species-rich genera are a source of debate among zoologists, as this is hard to come up with identification keys or perhaps even character sets that differentiate all species.

As a result, most taxonomists advocate for the division of large genera. For example, in genus and species examples, this has been proposed that the lizard genus Anolis be divided into 8 or so different genera, dividing its 400 species into smaller, relatively accessible subsets.

FAQ (Frequently Asked Questions)

Q1. Name the 5 Kingdoms?

Ans. Animals, plants, fungi, protists, and monera are the five kingdoms of life.

Q2. What's the difference between a Genus and a Species?

Ans. The difference between a genus and species: A genus is a higher level of classification than a species. The binomial name of an organism is made up of each of these classes. Humans, for example, are members of the genus Homo and the race sapiens. A genus is a set of species that are closely related.