MP Board · Class 12 · Biology · Biodiversity and ConservationExplain the three levels of biodiversity in detail. Why is biodiversity important for the ecosystem? Discuss the major causes of biodiversity losses.

Introduction to Biodiversity\nBiodiversity refers to the immense variety and variability of life on Earth. It encompasses all living organisms, from microscopic bacteria and fungi to complex plants and animals, as well as the ecological complexes of which they are a part. Biodiversity is generally categorized into three hierarchical levels:

1. Genetic Diversity

• Definition: Genetic diversity refers to the diversity of genes within a particular species. Every species is made up of individuals that have their own particular genetic makeup.
• Significance: A species with high genetic diversity has a better chance of surviving environmental changes, diseases, and climate shifts. For example, India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango.

2. Species Diversity

• Definition: Species diversity refers to the variety of species within a particular region or community. It is measured by species richness (the number of species per unit area) and species evenness (the relative abundance of different species).
• Significance: High species diversity ensures the stability and productivity of an ecosystem, as different species play unique ecological roles (e.g., Western Ghats have a greater amphibian species diversity than the Eastern Ghats).

3. Ecological Diversity

• Definition: Ecological diversity pertains to the variety of different ecosystems within a geographical location, such as deserts, rainforests, mangroves, coral reefs, wetlands, and alpine meadows.
• Significance: It represents the complexity of a biological community and the various trophic levels and interactions within ecosystems.

Importance of Biodiversity

• Ecological Stability: Ecosystems with high biodiversity are more resilient and resistant to natural and anthropogenic disturbances.
• Provision of Goods: Biodiversity provides food, timber, fiber, medicines, and industrial products.
• Ecosystem Services: It ensures pollination, nutrient cycling, climate regulation, soil formation, and flood control.

Causes of Biodiversity Losses (The 'Evil Quartet')

1. Habitat Loss and Fragmentation: Destruction of natural habitats due to urbanization, deforestation, and agriculture is the primary driver of extinction (e.g., tropical rainforests).
2. Over-exploitation: Excessive harvesting of natural resources by humans leads to the extinction of species, such as the Steller's sea cow and passenger pigeon.
3. Alien Species Invasions: Introduction of non-native species can threaten native flora and fauna due to the absence of natural predators (e.g., Water hyacinth and Nile perch).
4. Co-extinctions: When a species goes extinct, the plant and animal species associated with it in an obligatory relationship also become extinct (e.g., parasite and host species).