BIODIVERSITY & CONSERVATION:
CHAPTER AT A GLANCE
LEVELS OF BIODIVERSITY
- Genetic diversity: Diversity shown by a single species at the genetic level. E.g., Rauwolfia vomitoria shows genetic variation in reserpine.
- Species diversity: Diversity at the species level. E.g., Western Ghats have a greater amphibian species than Eastern Ghats.
- Ecological diversity: Diversity at the ecosystem level. E.g., deserts, rainforests, mangroves, etc.
TOTAL NUMBER OF SPECIES ON EARTH (GLOBAL SPECIES DIVERSITY)
Biologists are not sure about the number of prokaryotic species because
- Conventional taxonomic methods are not suitable to identify microbial species.
- In the laboratory, many species cannot be cultured.
PATTERNS OF BIODIVERSITY
i. Latitudinal gradients:
Species diversity decreases from the equator to the poles.
Biodiversity (species richness) is highest in the tropics because
- It had more evolutionary time.
- Relatively constant environment.
- It receives more solar energy.
IMPORTANCE OF SPECIES DIVERSITY
Rivet popper hypothesis: Proposed by Paul Ehrlich. In an airplane (ecosystem), if passengers pop a rivet (extinction of a species), it may not affect flight safety (functioning of the ecosystem). But as more rivets are removed, the plane becomes dangerously weak.
LOSS OF BIODIVERSITY
IUCN Red List (2004): E.g., Dodo, Quagga, Thylacine, Stellar’s sea cow, etc.
Causes of Biodiversity losses ('The Evil Quartet')
- Habitat loss & fragmentation: Most important cause.
- Over-exploitation: Stellar’s sea cow, Passenger pigeon, etc. extinct due to over-exploitation.
- Alien species invasions: Cause extinction of indigenous species. E.g., Nile Perch introduced in Lake Victoria caused the extinction of cichlid fish, African Catfish is a threat to indigenous catfishes in our rivers.
- Co-extinction: When a species becomes extinct, the species associated with it also becomes extinct. E.g., Parasites – host, Plant – pollinator.
BIODIVERSITY CONSERVATION
There are 3 categories of reasons for conservation.
- Narrowly utilitarian arguments: Humans derive economic benefits from nature such as food, firewood, industrial products, and medicines.
- Broadly utilitarian arguments: Biodiversity has ecosystem services. E.g., production of O2, Pollination, Aesthetic pleasures.
- Ethical arguments: Every species has intrinsic value. We have a moral duty to care for their well-being.
a. In situ conservation (on site): Conservation of organisms within natural or human-made ecosystems. E.g.,
- National Park: Reserved for the welfare of wildlife where private ownership, cultivation, grazing, etc. are prohibited. E.g., Eravikulam National Park.
- Sanctuary: Protection only to the animals. Collection of timbers, minor forest products, and private ownership are allowed. E.g., Periyar wildlife sanctuary.
- Biosphere Reserves: Areas of land or coastal ecosystems for conservation and sustainable use.
- Sacred forests (Sacred groves): Forest fragments that are communally protected based on religious beliefs.
- Conservation of organisms outside their habitats.
- E.g., genetic resource centres, zoological parks, wildlife safari parks, botanical gardens, gene banks, cryopreservation, etc.
- The regions with very high species richness, high endemism but most threatened.
- There are 34 hotspots in the world.
- 3 hotspots cover India’s biodiversity regions- Western Ghats & Sri Lanka, Indo-Burma and Himalaya.