Ecology and Environment - Biodiversity and its Conservation

Biodiversity is the term popularized by the sociobiologist $Edward\ Wilson$ to describe the combined diversity at all levels of biological organization.

Genetic Diversity: Variation at the genetic level within a single species, e.g., the medicinal plant $Rauwolfia\ vomitoria$ growing in different Himalayan ranges produces different concentrations of the active chemical $reserpine$.

Species Diversity: Diversity at the species level, e.g., the $Western\ Ghats$ have a greater amphibian species diversity than the $Eastern\ Ghats$.

Ecological Diversity: Diversity at the ecosystem level, including deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows.

Latitudinal Gradients: Species diversity decreases as we move away from the equator towards the poles. Tropical areas ($23.5^\circ N$ to $23.5^\circ S$) harbor more species than temperate or polar areas.

Species-Area Relationship: $Alexander\ von\ Humboldt$ observed that within a region, species richness increases with increasing explored area, but only up to a limit. The relationship is a rectangular hyperbola.

The 'Evil Quartet' of Biodiversity Loss: 1. Habitat loss and fragmentation, 2. Over-exploitation, 3. Alien species invasions (e.g., $Nile\ perch$, $Lantana$, $Eichhornia$), and 4. Co-extinctions.

In-situ Conservation: 'On-site' conservation where the whole ecosystem is protected (e.g., $National\ Parks$, $Wildlife\ Sanctuaries$, $Biosphere\ Reserves$, and $Sacred\ Groves$).

Ex-situ Conservation: 'Off-site' conservation where threatened animals and plants are taken out from their natural habitat and placed in special settings (e.g., $Zoological\ Parks$, $Botanical\ Gardens$, and $Cryopreservation$ of gametes at $-196^\circ C$).