Indian biodiversity — flora, fauna, endemic & keystone species

Biodiversity is not a list of pretty species; it is the variability of life at genetic, species and ecosystem levels, and UPSC uses that layered meaning to test Indian examples.

• Three levels: genetic diversity means variation within a species, such as rice landraces, millets, wild relatives of crops and locally adapted livestock breeds; species diversity means the number and relative abundance of species; ecosystem diversity means forests, grasslands, wetlands, deserts, islands, coasts and marine systems.
• Indian scope: India is treated as a megadiverse country because it has only about 2.4% of the world's land area but supports a large share of recorded species, several biogeographic zones, four global biodiversity hotspots and a major store of traditional knowledge.
• Flora and fauna: flora covers plants, algae, fungi in many survey contexts and forest vegetation; fauna covers animals from insects and molluscs to fishes, amphibians, reptiles, birds and mammals. In prelims, do not reduce fauna to large mammals.
• Endemism: an endemic species is naturally restricted to a defined area. The area may be a hill range, island group, river basin or hotspot. High endemism plus habitat loss creates conservation priority.
• Keystone role: a keystone species has ecological effects much larger than its abundance suggests. Apex predators, large herbivores, pollinators, seed dispersers and reef-building organisms can hold food webs, vegetation structure or nutrient cycling together.
• Exam trap: flagship species such as tiger or elephant attract public attention; umbrella species protect many co-occurring species when their large habitats are conserved; keystone species are defined by ecological function, not popularity.
• Static-plus-current mix: this topic links NCERT ecology, standard environment basics, Wildlife Protection Act schedules, Biological Diversity Act institutions, forest-cover data and contemporary debates on corridors, invasive species and development projects.
• Prelims method: remember examples by role and habitat: tiger as apex predator and umbrella species in forest landscapes, elephant as ecosystem engineer and seed disperser, mangroves as coastal habitat, coral reefs as marine biodiversity centres, and Western Ghats amphibians as endemism indicators.