#biology #species

Species

The smallest natural group of organisms is the

species. A species is a group of organisms that can

reproduce to produce fertile offspring.

Members of a species also often look very similar

to each other in appearance, Common mynas, eagles

and parrots are three different species of bird. Apart

from small variations, members of a species are

almost identical in their anatomy, physiology and

behaviour. Animals may look quite different if humans

have been involved in their breeding programmes.

For example, all cats belong to the same species,

but there are wide variations in the appearance of

different breeds (see ‘Variation’ in Chapter 18). An

American Longhair and a Siamese may look very

different but they breed together successfully.

Closely related species are grouped into a

genus (plural: genera). For example, there are

45 species of bronzeback snake, all in the same

genus Dendrelaphis.

Binomial nomenclature

Species must be named in such a way that the name

is recognised all over the world.‘Money Plant’ and ‘Devil’s Ivy’ are two common

names for the same wild plant. If you are not aware

that these are alternative names this could lead

to confusion. If the botanical name, Epipremnum

aureum, is used there is no chance of error. The

Latin form of the name allows it to be used in

all the countries of the world regardless of

language barriers.

People living in the Indian subcontinent

are familiar with the appearance of a robin.

The male is mainly black, with some red–brown

bottom feathers (although some more northern

populations are more brown than black). Males

also have a white flash across their shoulder. The

female has completely brown upper feathers and

grey–brown underparts. Its scientific name is

Copsychus fulicatus and the adult is about 17 cm

long (see Figure 1.1). However, someone living in

Britain would describe a robin very differently.

It has the species name Erithacus rubecula, and

is very distinctive. It has a round body with

a bright orange–red breast, a white belly and

olive–brown upper feathers. It is only 14 cm long

(see Figure 1.2). A British scientist could get very

confused talking to an Indian scientist about

a robin! Again, the use of the scientific name

avoids any confusion.The binomial system of naming species is

an internationally agreed system in which the

scientific name of an organism is made up of

two parts, showing the genus and the species.

Binomial means ‘two names’; the first name gives

the genus and the second gives the species. For

example, the Egyptian mongoose and Indian grey

mongoose are both in the genus Herpestes but they

are different species; the Egyptian mongoose is

Herpestes ichneumon and the Indian grey mongoose

is Herpestes edwardsii.

The name of the genus (the generic name) is

always given a capital letter and the name of the

species (the specific name) always starts with a

lowercase letter.

Often, the specific name is descriptive,

for example, edulis means ‘edible’, aquatilis

means ‘living in water’, bulbosus means ‘having

a bulb’, serratus means ‘having a jagged

(serrated) edge’.