Biodiversity and Conservation

Notes

Biodiversity refers to the variety and variability of living organisms present on Earth.

It includes diversity at the genetic, species and ecosystem levels.

The term biodiversity was popularised by sociobiologist Edward Wilson.

Levels of Biodiversity

Biodiversity can be studied at three major levels:

1. Genetic Diversity
2. Species Diversity
3. Ecological Diversity

2. Genetic Diversity

Genetic diversity refers to diversity or variation at the genetic level within a species.

A single species may show high diversity at the genetic level over its distributional range.

Examples of Genetic Diversity

• India has more than 50,000 genetically different strains of rice.
• India has about 1,000 varieties of mango.
• Rauwolfia vomitoria, a medicinal plant growing in different Himalayan ranges, shows variation in the potency and concentration of the active chemical reserpine.

Different subspecies, varieties, breeds, forms and strains contribute to genetic diversity.

3. Species Diversity

Species diversity refers to diversity at the species level in a particular geographical region.

For example, the Western Ghats have greater amphibian species diversity than the Eastern Ghats.

Species Richness

Species richness refers to the number of different species present per unit area.

• Greater species richness indicates greater species diversity.
• Lower species richness indicates lower species diversity.

Species Evenness

Species evenness refers to the relative abundance of different species present in an area.

4. Ecological Diversity

Ecological diversity refers to diversity at the ecosystem level.

It represents the variety of ecosystems and habitats present in a geographical region.

Examples

• Rainforests
• Deserts
• Wetlands
• Coral reefs
• Mountains
• Alpine meadows

India has greater ecosystem diversity than a Scandinavian country such as Norway.

5. Magnitude of Biodiversity

According to the IUCN (2004), the total number of plant and animal species described was slightly more than 1.5 million.

However, a large number of species are still waiting to be discovered and described.

According to a scientifically sound estimate made by Robert May, global species diversity is about 7 million.

Distribution of Known Species

• More than 70% of all recorded species are animals.
• Plants comprise about 22% of the total recorded species.
• Among animals, insects are the most species-rich taxonomic group.
• More than 70% of animal species are insects.
• The number of fungi species is greater than the combined total of fishes, amphibians, reptiles and mammals.