IGCSE Biology 0610 - 1.2 Concept and uses of classification systems

Objective: Describe a species as a group of organisms that can reproduce to produce fertile offspring.

What is a Species?

A species is defined as a group of organisms that are capable of interbreeding and producing fertile offspring. This means that the offspring produced are also able to reproduce themselves.

This definition is known as the biological species concept. It's a widely used and generally effective way to define species.

It's important to note that this definition isn't always perfect. There can be cases where organisms that look very similar cannot successfully reproduce, or where closely related populations can no longer interbreed due to geographical barriers or other factors.

Key Characteristics of a Species

• Ability to interbreed: Individuals within a species can mate with each other.
• Production of fertile offspring: The offspring produced from these matings are capable of reproducing themselves.
• Genetic similarity: Members of the same species share a significant amount of genetic material.
• Similar physical characteristics: Although not always a definitive indicator, members of the same species often share similar physical traits.
• Similar behaviour: Species often exhibit similar behaviours.

Examples

Consider the following examples:

• Humans: Humans can interbreed and produce fertile offspring. Therefore, all humans belong to the same species (Homo sapiens).
• Dogs: Different breeds of dogs can interbreed and produce fertile offspring. Therefore, all dogs belong to the same species (Canis lupus familiaris).
• Different species of plants: A rose and a sunflower cannot interbreed and produce fertile offspring. Therefore, they belong to different species.

Why is the Species Concept Important?

The concept of a species is fundamental to biological classification. It allows us to group organisms together based on their evolutionary relationships and shared ancestry.

Understanding the species concept is crucial for:

• Identifying and naming organisms.
• Understanding evolutionary relationships.
• Conservation efforts: Identifying distinct species is essential for protecting biodiversity.

Table Summary

Characteristic	Description
Species Definition	A group of organisms capable of interbreeding to produce fertile offspring.
Biological Species Concept	The most commonly used definition of a species.
Interbreeding	The ability of individuals to mate.
Fertile Offspring	Offspring capable of reproducing themselves.