Biodiversity and Conservation

Introduction

Earth is home to an estimated 8–10 million species (though only about 1.8 million have been scientifically described). The variety and variability of all living organisms — their genes, species, and ecosystems — is collectively called biodiversity. This biological richness underpins human survival, yet it is being lost at an unprecedented rate. This chapter explores the concept, importance, threats, and conservation of biodiversity.

What is Biodiversity?

The term biodiversity (biological diversity) was popularised by E.O. Wilson and covers three levels:

1.Genetic diversity: Variation in genes within a species. Example: different varieties of rice or wheat. High genetic diversity allows species to adapt to changing environments.
2.Species diversity: The variety of species in a given region. Measured by species richness (number of species) and species evenness (relative abundance).
3.Ecosystem diversity: Variety of habitats, ecological communities, and processes. Includes forests, wetlands, deserts, coral reefs, grasslands, and oceans.

Biodiversity Patterns

Latitudinal gradient: Species diversity generally decreases from the equator to the poles. Tropical regions (especially rainforests) have the highest species richness; polar regions have the lowest. Explanations include: longer evolutionary time in tropics, higher energy availability, greater habitat complexity, more stable climate over geological time.

Altitude gradient: Similar to the latitudinal gradient — diversity decreases with altitude.

Species-area relationship: As area increases, the number of species also increases, generally following the formula S = C x A^z, where S = number of species, A = area, C and z are constants. The value of z typically ranges from 0.1 to 0.2 for large continental areas.

Biodiversity hotspots: Regions with exceptional species richness and high levels of endemism (species found nowhere else), which are also under severe threat. About 36 biodiversity hotspots have been identified globally, including the Himalayas and the Western Ghats in India. These hotspots cover <3% of Earth's surface but contain >50% of the world's plant species.

Importance of Biodiversity

Direct values: Food (crops, livestock, fisheries), medicine (about 25% of pharmaceutical drugs derive from plant compounds), timber, fibre, fuel, tourism.
Indirect (ecosystem service) values: Pollination (bees, butterflies), seed dispersal, climate regulation (forests), water purification, soil formation, nutrient cycling, flood control, carbon sequestration.
Option value: Future potential uses not yet discovered (pharmaceutical, agricultural).
Existence value: Intrinsic moral right of species to exist, regardless of human use.
Keystone species: Species whose disproportionate role is critical to ecosystem function (e.g., sea otters maintaining kelp forests; tigers regulating prey populations).

Threats to Biodiversity (HIPPO)

The major drivers of biodiversity loss (acronym: HIPPO):
H — Habitat loss and fragmentation: The greatest threat. Deforestation, agriculture expansion, urbanisation, drainage of wetlands. Fragmentation isolates populations, reducing genetic exchange.
I — Invasive species: Non-native species introduced to new areas that outcompete, prey on, or infect native species. Example: Nile perch extinguished ~200 cichlid species in Lake Victoria; water hyacinth (Eichhornia) chokes Indian waterways.
P — Pollution: Air, water, and soil pollution harm organisms directly or disrupt food chains (e.g., DDT causing thinning of bird egg shells, causing raptor population collapse).
P — Population (human): Growing human population drives all other threats by increasing demand for land, resources, and energy.
O — Overexploitation: Hunting, fishing, and harvesting at rates that exceed natural reproduction. Example: Atlantic cod nearly extirpated by overfishing.

Climate change is increasingly recognised as an additional major driver — shifting habitats, changing phenology, bleaching coral reefs, and forcing species migrations.

Conservation Strategies

Conservation can be:
In-situ conservation: Protecting species in their natural habitat. Most preferred approach.
National Parks: Protected areas where no human habitation or exploitation is permitted.
Wildlife Sanctuaries: Area protected for wildlife; some human activities may be permitted.
Biosphere Reserves: Larger zones for conservation AND sustainable use; have core, buffer, and transition zones.
Sacred Groves: Forest patches protected by local communities for religious reasons; traditional conservation.
Community Reserves: Areas managed by local communities.

Ex-situ conservation: Preserving species outside their natural habitat.
Zoological parks (zoos), botanical gardens, aquaria.
Seed banks: Storage of seeds at low temperature and humidity for long-term preservation (e.g., National Bureau of Plant Genetic Resources, India; Svalbard Global Seed Vault, Norway).
Cryopreservation of genetic material (sperm, eggs, embryos).

Conservation in India

India is one of the world's 17 megadiverse countries. It has:
5 major biodiversity hotspots: Western Ghats and Sri Lanka, Eastern Himalayas, Indo-Burma, and Sundaland (partly).
104 National Parks, 567 Wildlife Sanctuaries, and 18 Biosphere Reserves (as of recent figures).
Project Tiger (1973): Increased wild tiger population from ~1827 (2002) to over 3000 (2022 census).
Project Elephant: Protection of elephants and their corridors.

International Conventions

Convention on Biological Diversity (CBD, 1992): Signed at Rio Earth Summit; three goals: conservation of biodiversity, sustainable use of components, fair sharing of benefits from genetic resources.
CITES: Convention on International Trade in Endangered Species — regulates international trade in threatened species.
Ramsar Convention: Protection of wetlands of international importance.
IUCN Red List: Global assessment of conservation status of species (Extinct, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern).

Common mistakes

In-situ conservation is protecting species IN their natural habitat (in parks, reserves); ex-situ is OUTSIDE (zoos, seed banks).
Biodiversity hotspots are selected for high endemism AND high threat — not just biodiversity richness alone.
National Parks have stricter protection than Wildlife Sanctuaries — no human settlements inside national parks.
The latitudinal gradient means MORE species near the equator, not fewer.

Summary

Biodiversity encompasses genetic, species, and ecosystem diversity and is highest in tropical regions. It provides direct goods and essential ecosystem services. Major threats include habitat loss, invasive species, pollution, overexploitation, and climate change. Conservation strategies include in-situ (national parks, biosphere reserves) and ex-situ (zoos, seed banks) methods, supported by national and international frameworks.