BIODIVERSITY AND CONSERVATION · Comparison Tables

1. Genetic, species and ecological diversity

Three important levels of biodiversity
Level	Meaning	NCERT example
Genetic diversity	Variation in genes within a species across its range.	Rauwolfia vomitoria varies in reserpine potency; India has more than 50,000 rice strains and 1,000 mango varieties.
Species diversity	Variety of species in a region.	Western Ghats have more amphibian species than Eastern Ghats.
Ecological diversity	Variety of ecosystems/habitats.	India has deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows.

2. Tropics vs temperate/polar regions

Latitudinal gradient in species richness
Feature	Tropics	Temperate and polar regions
Species richness	Generally highest between 23.5 degrees N and 23.5 degrees S.	Generally falls away from equator toward poles.
Evolutionary history	Longer uninterrupted evolutionary time.	More affected by past climatic changes/glaciations.
Environment	Less seasonal, more constant and predictable; promotes niche specialisation.	More seasonal and variable.
Energy	More solar energy and productivity.	Relatively lower energy input and productivity.

3. Small-scale vs continental species-area relationship

Species richness rises with area
Feature	Most regional comparisons	Very large areas / continents
Relationship	Rectangular hyperbola; log S = log C + Z log A.	Same broad relationship, but steeper slope.
Z value	Usually 0.1-0.2 across many taxa/regions.	Usually 0.6-1.2.
Meaning	Moderate increase in species richness with area.	Greater increase across huge geographic scales.

4. Stable vs unstable community

Effects associated with high species richness
Feature	Stable community	Unstable community
Productivity	Little year-to-year variation.	Greater variation in total biomass/productivity.
Disturbance	Resistant or resilient to natural/man-made disturbance.	Less able to maintain function after disturbance.
Alien invasion	More resistant to invasion.	More vulnerable to biological invasions.
Evidence	Tillman's plots with more species had less biomass variation and greater productivity.	Lower diversity generally weakens these effects.

5. Background vs sixth mass extinction

Loss of species through time
Feature	Past / background extinctions	Current sixth extinction
Rate	Natural losses across evolutionary time; five historic mass-extinction episodes occurred.	Estimated 100-1,000 times faster than pre-human rates.
Driver	Natural geological and environmental events.	Largely human activities.
Risk	Part of long-term evolutionary history.	Nearly half of Earth's species could be lost within the next 100 years if trends continue.

6. The Evil Quartet: causes of biodiversity loss

Major human-driven causes
Cause	Meaning	Example
Habitat loss and fragmentation	Habitat destruction and division into small isolated patches.	Deforestation and degradation of forests.
Over-exploitation	Harvesting faster than populations can recover.	Steller's sea cow, passenger pigeon and overharvested marine fish.
Alien species invasion	Introduced species become invasive and displace natives.	Nile perch in Lake Victoria; Parthenium, Lantana, water hyacinth and African catfish in India.
Co-extinction	Obligately associated species disappear with a lost partner.	Host fish and its parasites; coevolved plant-pollinator pair.

7. Utilitarian vs ethical reasons to conserve

Why biodiversity matters
Reason	Basis	Examples
Narrowly utilitarian	Direct economic value.	Food, firewood, fibre, medicines, industrial products and crop genetic resources.
Broadly utilitarian	Ecosystem services supplied by nature.	Oxygen production, pollination, flood/erosion control, nutrient cycling and climate regulation.
Ethical	Every species has intrinsic value; humans have a moral duty to future generations.	Care for co-inhabitants even without immediate economic value.

8. In situ vs ex situ conservation

Two conservation approaches
Feature	In situ conservation	Ex situ conservation
Meaning	On-site protection in natural habitat/ecosystem.	Off-site protection outside natural habitat.
Approach	Protects whole ecosystem and all levels of biodiversity.	Gives threatened species special care in controlled settings.
Examples	Biosphere reserves, national parks, wildlife sanctuaries and sacred groves.	Zoos, botanical gardens, wildlife safari parks, seed banks and cryopreservation.
Best use	"Save the entire forest to save the tiger."	Urgent support when species faces high near-term risk in wild.

9. Biodiversity hotspots vs protected areas

Priority and legal conservation tools
Feature	Hotspots	Protected areas
Focus	Regions with high endemism and high habitat loss.	Legally protected biodiversity-rich ecosystems.
Goal	Strict protection can reduce ongoing mass extinctions substantially.	Conserve habitats, wildlife and ecosystem processes.
Indian examples	India contains portions of several global hotspots.	Biosphere reserves, national parks, sanctuaries and sacred groves such as those in Meghalaya.