Previous Year Question

Biodiversity Loss refers to the decline in species, their populations, and Genetic Diversity within a particular region. Its most significant cause is Habitat Loss and Fragmentation. Activities such as deforestation, agricultural expansion, urbanization, mining, road construction, and dam building destroy natural habitats or divide them into smaller fragments. Consequently, organisms face difficulties obtaining food, shelter, breeding sites, and other essential resources.

Habitat Fragmentation divides previously connected forests, grasslands, or wetlands into isolated patches. This affects wildlife movement, reproduction, and Gene Flow between populations. Small, isolated populations may face increased risks of Inbreeding, reduced genetic diversity, and Local Extinction. Changes in temperature, light, humidity, and predator activity along the boundaries of fragmented habitats are known as the Edge Effect, which can particularly affect species dependent on interior habitat conditions.

Other major causes of biodiversity loss include Overexploitation, Invasive Alien Species, and Pollution. Excessive hunting, fishing, and uncontrolled exploitation of forest resources reduce species populations. Invasive Alien Species may compete with native organisms for food and habitat. For example, Water Hyacinth (Pontederia crassipes) spreads rapidly in water bodies, affecting native aquatic vegetation and ecological processes. Similarly, pollution caused by industrial waste, pesticides, and fertilizers damages aquatic and terrestrial biodiversity.

NCERT describes four major causes of biodiversity loss as the ‘Evil Quartet’—Habitat Loss and Fragmentation, Overexploitation, Invasion by Alien Species, and Co-extinction. Co-extinction may occur when the extinction of one species leads to the extinction of another species dependent upon it. The 2019 Global Assessment of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) identified changes in land and sea use as the most influential global direct driver of biodiversity loss. Protecting natural habitats, establishing Biological Corridors, and restoring degraded ecosystems are important measures for limiting biodiversity decline.