Difference Between Species And Genus, Simple Guide, Examples


Here we’ve decided to discuss the differences between Species and Genus and hopefully apply simple terms so that adults and children can understand how it works. First, let’s offer a quick answer then we’ll look into more detail…

What Is The Difference Between Species And Genus? The main difference between species and genus is the taxonomic rankings that are used for biological classifications of organisms. Genus belongs to a ranking lower than family and above species, whereas species are organisms with similar characteristics that come below the Genus classification ranking.

For those who might still be confused, let’s walk you through this and focus on the difference between these two confusing or often misunderstood names genus and species that are used as a standard format for naming organisms.

Let’s start with the Genus…

What Is A Genus

The word genus originates from a Greek term meaning “race”. So in a taxonomic hierarchy, this ranks above species – and below family (which is another classification in the taxonomic hierarchy).

Genus consists of structurally …or phylogenetically related groups of organisms, or a single solitary organism exhibiting unusual differentiation (monotypic genus).

Two organisms from the same genus may produce fertile offsprings. But two organisms from two different genera cannot produce offsprings that are capable of reproduction. 

When writing the scientific names of organisms it begins with the Genus name, with the first letter of the Genus name capitalized followed by a period. A genus name is also referred to as the generic epithet (by botanists) or generic name (by zoologists). The following are the criteria used to define an organism to a specific genus.

Examples of Genus

The following are a few examples of Genus.

  • Human – Homo 
  • Rose – Rosa (Th Genus Rosa has four subdivisions including Hulthemia, Hesperrhodos and Platyrhodon and Rosa (the type subgenus – all the roses that don’t belong to any other subgenus is classified in Rosa)
  • ZebraHorse, and Donkeys – Equus (In here plains zebra and the mountain zebra belong to the subgenus Hippotigris, while Grévy’s zebra belongs to the subgenus Dolichohippus)
  • Madrone butterfly – Eucheira (The madrone butterflies are the only organism in the genus Eucheira making it a monotypic genus)

If we take the example of a horse in its entire taxonomic classification, it would list as below, in this example, you can see where we’ve highlighted both the Species and Genus positions on the scale.

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Perissodactyla
  • Family: Equidae
  • Genus: Equus
  • Species: E. ferus
  • Subspecies: E. f. caballus

What Is A Species

Species are the most basic level in a taxonomic hierarchy. Species are a group of organisms with similar features (that are intrinsic only to their species), identical chromosomes count (meaning they have similar form and structure) and sometimes even similar habitat …who produce fertile offspring when they breed.

For defining a specific species the DNA sequences, morphological, and ecological features are taken into consideration. 

When writing the scientific name of an organism the name of the species is written as the second part. The species name is written in italics and lowercase letters. In zoology, a species name is also called a “specific name,” while botanists refer to it as a “specific epithet.”

Examples of Species

The following are some examples of a few species.

  • Human – sapiens 
  • Different roses – Shrub rose is “Flutterbye”, red climbing rose “Santana”, double pink shrub rose “Hybrid”.
  • Zebra – zebra 
  • Horse – ferus  
  • Donkeys – africanus
  • Madrone butterfly – socialis

It’s also important to remember that some species will have subspecies which will make their scientific names a bit lengthy (but they’re not usually included in the scientific name).

If we take the example of a Horse in isolation, we’ve listed the Classification structure below. You can see where we’re highlighted both the Genus, the Species, and the Sub-Species to help you understand their placement in the hierarchy.

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Perissodactyla
  • Family: Equidae
  • Genus: Equus
  • Species: E. ferus
  • Subspecies: E. f. caballus

As an additional example, the species name for tiger is “tigris” and subspecies such as the Bengal tiger is named as “tigirs tigris”, the Sumatran tiger “tigris sumatrae” and the Siberian tiger “tigris altaica”. As you can see from its hierarchical example laid out below, we’ve highlighted where the species name is then followed by the subspecies name.

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Carnivora
  • Suborder: Feliformia
  • Family: Felidae
  • Subfamily: Pantherinae
  • Genus: Panthera
  • Species: P. tigris
  • Subspecies: P. t. tigris

Difference Between Genus And Species Based On Different Factors

Level Of Ranking In The Taxonomic Hierarchy 

Genus is a taxonomic classification, which ranks below family (and any Subfamily) and above Species. Whereas species is a taxonomic classification that ranks below Genus in the taxonomy hierarchy, but it is the fundamental level of classification for an organism.

Composition

A genus is composed of many different species, whereas species are composed of different subspecies. One example of this is the plant “Rose” which belongs to the Genus “Rosa” which has more than 100 “Species” of Rose and further different subspecies.

For detailing it more, “hybrid” is a species of rose that has subspecies such as “fair bianca”, ”gizmo” and “iceberg”, whereas “floribunda” is another species of rose that has several subspecies such as “cherish”, “disneyland” and  “europeana” and these all come under the genus “Rosa”. See the chart below which outlines how this hierarchy works.

difference species genus, with sub-species example
difference species and genus, with sub-species examples

Number Of Organisms in each category

A genus consists of a large number of organisms, whereas species consists of a fewer number of organisms. The best example is animals like zebra, horses, and donkeys which belong to the same Genus “Equss”. Meaning all the different species of zebra, donkey, and horses all belong to Equss.

Whereas zebra belongs to the species “zebra”, horses belong to the species “ferus” and donkeys to the species “africanus” which are all very small/limited in number for each organism. 

In Binomial Nomenclature

In taxonomy, there’s a scientific naming process called “Binomial Nomenclature” which gives every single organism two names. You can compare this to your name which consists of the first name and the surname.

This systematic naming process names organisms by considering the genus name as the first name followed by the species and subspecies (but very rarely are subspecies names used for the binomial name) as the sir/last name.

As an example:-

For red climbing rose the scientific name is, “Rosa santana” where Rosa is the Genus and “santana” is the species.

In cases of subspecies, it’s named as “Rosa floribunda angel face”, “Rosa floribunda cherish” and “Rosa foribunda cinco de mayo”. As you can clearly see the genus (Rosa) and the species (floribunda) remains the same – while the subspecies names keep changing as “angel face”, “cherish” and “cinco de mayo”.

(There are rules on how to name the genus and species, which we’ve previously outlined above).

Reproduction Capability/ Fertility

Organisms between separate genera can never produce offsprings that are fertile or capable of reproduction. In contrast species and its subspecies can produce fertile offspring. Whereas organisms from separate species but under a specific (one common) genus may or may not be able to reproduce fertile offspring.

To finish…

It’s a complex area to get your head around. But it’s a clever system that has stood the test of time – even though it has had to be expanded upon occasionally.

We hope we’ve been able to shed some light on the fundamental differences between Genus and Species in as simple a way as possible. If you have anything to add or further comments then we’d really like to hear from you.

Here’s a Video which may help to explain it further…

genus and species difference video


Michael

A Certified Ecologist and an Entomologist, Michael has been interested in all aspects of Nature for many years. It's only now he's decided, along with his partner Fran, to begin documenting what he knows.

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