Unit 6: The diversity of life                                                         1   2   3

3. Biodiversity

Biodiversity is the number of different species of living beings that exist on Earth.

Scientists believe there may be more than thirty million species, of which only two million species have been classified.

3.1. The origin of biodiversity

Biodiversity is the result of a slow process called evolution. Evolution began with the first life forms and still continues today. 

Adaptation is the process of adjustment of living beings to their changing environment. The great diversity of environments that exist on the Earth provokes that living beings have to change and adapt to the different conditions to survive. This process gives as a result a great quantity and variety of species.

Biodiversity varies tremendously throughout the world. It is influenced by climate and habitats. For example, more than half the world's species live in tropical rain forests and coral reefs.

Some countries, for example Spain, have many different climate zones and habitats. As a result, they have more biological diversity. 

3.2. The importance of biodiversity

Biodiversity is a natural resource that we must preserve because we depend on it.

The values of biodiversity are several:

-Economic value: Living beings provide us with food, medicines,

 raw materials and energy.

-Recreational value: Natural environment is a source of economic incomes

 by tourism and satisfies our need for leisure and have benefitial effects 

 on our health.

-Scientific value: Keeping biodiversity allows that the scientists know better

 the nature and how it works.

-Ecological value: Each species plays a determinate role in the ecosystem.

  They depend on each other and they all are important to maintain

  the ecological balance.

-Genetic value: Each species stores in their genes, the adaptations it had

  to develop to survive.

3.3. The loss of biodiversity

Many species become extinct or they are endangered every day for these factors:

- Destruction of habitats caused by deforestation (for burning or

  logging), construction. etc.

- Overexploitation of resources, such as uncontrolled hunting and fishing

  that put in danger many species (E. g. Iberian Lynx)

- Pollution of water, soil and atmosphere, caused by agriculture, industry

  and urban development.

- Introduction of exotic species that can destroy local species

  (E.g. River crab)

3.1. Listen and indicate which concept is defined:

3.2. Indicate why:

a. Living beings have to adapt.

b. It is dangerous to introduce exotic species in natural habitats.

c. It is important to protect the endangered species.

d. Spain has more biodiversity than other European countries.

3.3. Match each photo with a factor that reduces biodiversity.

3.4. Listen and indicate which value of biodiversity each sentence refers to: