Biodiversity

Biodiversity

• Varieties of life on the earth exists over thousands of years to fulfill the needs of mankind. For understanding the life cycle of plants and animals they must be classified and categorized properly.

Biodiversity (Biological diversity) is defined as variety and variability of living organisms in a given assemblage. Biodiversity covers whole life on earth.

• Biodiversity may be described in terms of genes, species and ecosystems, corresponding to three fundamental and hierarchically related levels of biological organization.

• All life depends on uninterrupted functioning of natural systems that ensure the supply of energy and nutrients, so ecological responsibility among all people is necessary for survival, security, equality and dignity of the world's communities.

1. Importance of Biodiversity

1. Increase ecosystem productivity; each species in an ecosystem has a specific role to play.

2. Support a larger number of plant species and, therefore, a greater variety of crops.

3. Protect freshwater resources.

4. Promote soils formation and protection.

5. Provide for nutrient storage and recycling.

6. Aid in breaking down pollutants.

7. Contribute to climate stability.

8. Speed recovery from natural disasters.

9. Provide more food resources.

10. Provide more medicinal resources and pharmaceutical drugs.

11. Offer environments for recreation and tourism.

2. Types of Biodiversity

• There are three basic types of biodiversity -

1. Genetic diversity

2. Species diversity

3. Ecosystem diversity or community diversity.

3. Genetic Diversity

• Genetic diversity is a measure of variety available for the same genes within individual species.

• Genetic diversity is based on variation between genes i.e. functional units of hereditary information. The genetic variability is essential for a healthy breeding population of a species.

Example : Each human being is different from all other, thousands of rice varieties are available.

4. Species Diversity

• Species diversity is the number of different species of living things within an area.

• Species are regarded as populations within which gene flow occurs under natural conditions. Members of one species, do not breed freely with members of other species.

Examples : Tiger, lion, teakwood, human being etc.

5. Ecosystem Diversity

• Ecosystem diversity relates to the variety of habitats, biotic communities and ecological processes in the biosphere as well as the diversity within ecosystems.

• Diversity can be described at a number of different levels and scales :

* Functional diversity is the relative abundance of functionally different kinds of organisms

* Community diversity is the number sizes and spatial distribution of communities, and is sometimes referred to as patchiness (uneven quality)

* Landscape diversity is the diversity of scales of patchiness.

• No simple relationship exists between the diversity of an ecosystem and ecological processes such as productivity, hydrology and soil generation.

• Neither does diversity correlate neatly with ecosystem stability, nor its resistance to disturbance and its speed of recovery.

• There is no simple relationship within any ecosystem between a change in its diversity and the resulting change in the system's processes.

• For example, the loss of a species from a particular area or region (local extinction or extripation) may have little or no effect on net primary productivity of competitors take its . place in the community.

• The converse may be true in other cases. For example, if herbivorous such as zebra and wild beasts are removed from the African savanna, net primary productivity of the ecosystem decreases.

Review Questions

1. Define the term biodiversity. What are its values ?

2. What is meant by genetic diversity ? Species diversity and ecosystem diversity.