Difference between Genus and Species
All living organisms present on the earth are categorized into groups for easier understanding. Taxonomy is a branch of science which deals with the scientific categorization of organisms into separate groups based on the presence and absence of certain characteristics. The characteristics may be physical or genetic. ‘Taxis’ in Greek refers to order and arrangement. Classification of all organisms including plants, animals and microbes according to a set of rules brings in uniformity and simplicity while studying these organisms across the globe. The taxonomic hierarchy consists of
Kingdom – Phylum – Class – Order – Family – Genus – Species.
Common names would have created lot of confusion as every country would have had a separate name for the same organism. The need to bring in standardization in the process of naming gave birth to the binomial naming system both in zoology and botany. This is a scientific naming process adopted all over the world across language barriers. It helps to reduce confusion.
Binomial naming system consists of giving two names to an organism. Just like we have a name and a surname, the organisms are named after their genus and species. These are the lowest two levels in the taxonomic system of naming. The first name is the genus followed by the name of their species. For example Homo sapiens refer to human beings. The word Homo refers to genus and the word sapiens refers to species. Let us understand certain differences between genus and species.
Species:
Species is defined as the largest group organisms that can interbreed to produce a fertile offspring. Organisms having similar set of DNA and similar physical and morphological attributes are said to be of the same species. They have the same number of chromosomes and thus possess similar morphological characteristics. The male and female of the same species can interbreed to produce a fertile offspring of the same species.
The name of the species or the specific name/epithet forms the second part of the binomial nomenclature. It is generally written in small letters and italics. Species are basically groups or populations of animals that have a high degree of genetic similarity. There may be many species under the same genus.
Genus:
‘Genus’ in Greek means ‘race’. It comes below the family and above the species in the taxonomic hierarchy. Many a times it is not possible to identify all organisms up to the level of the species, especially the fossilized and extinct ones. In such case identifying the genus of the organism is enough to label it.
A genus can have many species. Organisms of different species of the same genus cannot produce a fertile offspring if interbred together. Mule is a classic example of this. It is a product of a donkey and a horse which are two different species belonging to the same genus (Equus).
The genus or the generic name precedes the specific name in binomial classification. The first letter is written in capital letters. The generic name is also written in italics and can be abbreviated to the first letter. For example: Homo sapiens or H. sapiens.
To summarize genus and species are the lower most ranks in the taxonomic hierarchy of the scientific naming system.