BIODIVERSITY AND CONSERVATION

Biodiversity term popularised by Edward Wilson; combined diversity at all levels.

Three levels — Genetic, Species, Ecological diversity.

Robert May's estimate = ~7 million global species; IUCN documented = 1.5 million.

Fungi species > combined species of Fishes + Amphibians + Reptiles + Mammals.

Among invertebrates: Insects > Molluscs > Crustaceans > Others.

India — 2.4% land area but 8.1% global species diversity; one of 12 mega-diversity countries.

Latitudinal gradient — species diversity increases from poles to equator.

Amazon = greatest biodiversity on Earth.

Taxa numbers in Amazon (descending): Invertebrates > Plants > Fishes > Birds > Mammals.

Descending order of species number in the Amazonian rain forest — Invertebrates (>1,25,000) > Plants (>40,000) > Fishes (3,000) > Birds (1,300) > Mammals (427).

Three hypotheses for tropical species richness — evolutionary time, constant environment (niche specialisation), more solar energy (higher productivity).

Tropical latitudes remained relatively undisturbed for millions of years giving more time for species diversification; tropical environments are constant and predictable (LESS seasonal), which promotes niche specialisation; and more solar energy is available in the tropics.

Alexander von Humboldt — species-area relationship; rectangular hyperbola.

log S = log C + Z log A equation; know all variables.

Z values — 0.1–0.2 for taxonomic groups; 0.6–1.2 for continents; 1.15 for frugivorous birds & mammals.

David Tilman — more species = less variation + more productivity.

Rivet Popper Hypothesis — Paul Ehrlich; Airplane = Ecosystem; Rivets = Species; Wing rivets = Keystone species.

The sixth extinction, currently in progress, differs from the previous five in that present species extinction rates are 100 to 1000 times faster than in pre-human times.

IUCN Red List — 784 species extinct in last 500 years (338 vertebrates, 359 invertebrates, 87 plants).

Critically Endangered = species facing extremely high risk of extinction in immediate future.

Steller's sea cow and passenger pigeon became extinct due to over-exploitation by humans.

Match-the-list: Dodo ↔ Extinction.

Habitat loss & Fragmentation = MOST IMPORTANT cause.

The Evil Quartet = Habitat loss and fragmentation, Over-exploitation, Alien species invasions, and Co-extinctions — pollution (air, water, soil) is NOT part of the quartet.

Match-the-list: The Evil Quartet ↔ Causes of biodiversity losses.

When a species becomes extinct, the plant and animal species associated with it ARE affected — this is co-extinction.

The Amazon rainforest being cut and cleared for cultivation of soyabeans is an example of habitat loss.

Nile Perch → Lake Victoria → >200 cichlid species extinct.

African catfish (Clarias gariepinus) — threat to indigenous catfishes in Indian rivers.

Invasive species — Parthenium, Lantana, Eichhornia.

The Nile perch introduced into Lake Victoria DECIMATED the cichlid fish, causing extinction of more than 200 species.

Water hyacinth is an invasive species.

Match-the-list: Lantana camara ↔ Alien species invasion.

The Abingdon tortoise in the Galapagos islands became extinct within a decade after goats were introduced, because goats were more efficient at browsing than the tortoise.

Exploring molecular, genetic and species-level diversity for products of economic importance is called bioprospecting — not biomagnification, biofortification or bioremediation.

In-situ conservation — on-site; natural habitats.

In-situ methods = Hotspots (34), Biosphere Reserves (14), National Parks (90), Wildlife Sanctuaries (448), Sacred Groves.

Sacred Groves are an in-situ conservation method; Wildlife Safari Parks, Botanical Gardens and Seed Banks are all ex-situ.

34 biodiversity hotspots worldwide; < 2% land → reduce extinction by ~30%.

Endemism = species confined to a particular region, not found anywhere else.

Species found in the Western Ghats and nowhere else in the world are termed endemic — not vulnerable, threatened or keystone.

Three hotspots in India — Western Ghats & Sri Lanka, Indo-Burma, Himalaya.

Core zone of biosphere reserve — legally protected, no human activity.

Sacred Groves — forest patches protected by tribal/religious communities; Khasi & Jaintia Hills in Meghalaya.

Ex-situ methods — Zoos, Botanical Gardens, Seed Banks, Cryopreservation, IVF, Tissue culture.

Zoos and botanical gardens are examples of ex-situ conservation; protected areas, National Parks and Wildlife Sanctuaries are in-situ.

Match-the-list: Ex-situ conservation ↔ Cryopreservation.

Earth Summit — 1992; Rio de Janeiro; conservation + sustainable utilisation.

World Summit — 2002; Johannesburg; 190 countries; pledge to reduce biodiversity loss by 2010.