BIODIVERSITY AND CONSERVATION

Biodiversity includes variation from genes to ecosystems. This chapter examines its patterns and value, the human causes of rapid loss, and in situ and ex situ conservation.

Edward Wilson popularised the term biodiversity for combined diversity at all levels of biological organisation.

• Genetic diversity is variation within a species; species diversity is variety of species; ecological diversity is variety of ecosystems.
• More than 70% of recorded species are animals, and insects account for more than 70% of animal species. Fungi have more species than fishes, amphibians, reptiles and mammals combined.
• India has only 2.4% of world land area but about 8.1% of global recorded species diversity, making it one of 12 mega-diversity countries.

Species richness is unevenly distributed. It is highest in the tropics and declines toward poles.

• Tropical richness is explained by long evolutionary time, stable and predictable climate promoting niche specialisation, and high solar energy/productivity.
• Species richness rises with area. On log scale: log S = log C + Z log A; Z is usually 0.1-0.2 but 0.6-1.2 across continents.
• Communities with more species tend to show less year-to-year biomass variation, higher productivity and greater invasion resistance.

Current extinction rates are 100-1,000 times higher than pre-human rates. This human-driven sixth extinction could eliminate nearly half of Earth's species within a century if present trends continue.

• The four main causes - the Evil Quartet - are habitat loss and fragmentation, over-exploitation, alien species invasion and co-extinction.
• Alien invasives include Nile perch in Lake Victoria, Parthenium, Lantana, water hyacinth and African catfish.
• Loss of biodiversity lowers plant production, reduces resistance to environmental perturbation and increases variability in productivity, water use, pests and disease cycles.

• Narrowly utilitarian values include food, fibre, firewood, pharmaceuticals and genetic resources.
• Broadly utilitarian values are ecosystem services such as oxygen production, pollination, flood and erosion control, nutrient cycling and climate regulation.
• The ethical argument is that every species has intrinsic value and humans have a moral duty to pass biological heritage to future generations.

In situ conservation protects species in their natural habitat, preserving the complete ecosystem. It includes biosphere reserves, national parks, wildlife sanctuaries and sacred groves.

• Ex situ conservation protects threatened organisms away from their natural habitat through zoos, botanical gardens and safari parks.
• Modern ex situ methods include cryopreservation of gametes, in-vitro fertilisation, tissue culture and seed banks.
• Hotspots have high endemism and habitat loss; strict protection is a highly effective conservation priority.

• Biodiversity is genetic, species and ecological diversity.
• Tropics are species-rich; species richness also rises with area.
• Human activity drives the current rapid extinction crisis.
• The Evil Quartet: habitat loss, over-exploitation, alien invasion and co-extinction.
• Conservation is in situ (ecosystem protection) and ex situ (off-site protection).