Biodiversity and Biodiversity Hotspots
Biodiversity
- The variability among living organisms from all sources including terrestrial, marine and other aquatic ecosystems, and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems. Biological Diversity actually means number and variety of plants and animals
- As you move from equator towards the poles, biodiversity decreases
- Biodiversity is normally greater in the lower latitudes as compared to the higher latitudes
- Biodiversity is normally greater in the lower altitudes as compared to the higher altitudes
- Biodiversity is high in tropical forests and coral reefs
Biodiversity can be subdivided into three levels
Genetic Diversity
- It refers to the variation of genes within a species which enables a population to adapt to its environment and to respond to natural selection.
- Genetic diversity within a species often increases with environmental variability. For ex: Butterflies, Roses, Corals etc.
Species diversity
- Refers to variety of species within a region
Community & ecosystem diversity
- diversity of a place at the level of ecosystems i.e. variety of ecosystems present in a biosphere
- variety of species & ecological processes that occur in different physical settings
- differs from biodiversity, which refers to variation in species rather than ecosystems
Biodiversity is defined & measured on two components viz. richness & evenness
- Richness: Expressed as the number of species found in a community
- Evenness: Proportions of species or functional groups present on a site. The more equal species are in proportion to each other the greater the evenness of the site. A site with low evenness indicates that a few species dominate the site.
Alpha Diversity: richness and evenness of individuals within a habitat unit. For example in the figure above, Alpha Diversity of Site A = 7 species, Site B = 5 species, Site C = 7 species.
Beta Diversity: expression of diversity between habitats. In the example above, the greatest Beta Diversity is observed between Site A and C with 10 species that differ between them and only 2 species in common.
Gamma Diversity: landscape diversity or diversity of habitats within a landscape or region. In this example, the gamma diversity is 3 habitats with 12 species total diversity.
Plant biodiversity and Green Revolution
- Under the green revolution program, government introduced HYV (high yielding variety) seeds.
- So, instead of 30,000 indigenous varieties of rice, now Indian farmers plant only 12 HYV rice varieties → reduced biodiversity of rice.
Biodiversity Hotspot
- An area unusually rich in biodiversity under constant threat of overe xploitation for ex. Eastern Himalayas & Western Ghats
- To qualify as a biodiversity hotspot on Myers 2000 edition of the hotspot-map, a region must meet two strict criteria viz.
- Must have at least 1,500 species of vascular plants as endemics (> 0.5% of world’s total)
- Has to have lost at least 70% of its primary vegetation habitat
- Around the world, these sites support nearly 60% of the world’s plant, bird, mammal, reptile, and amphibian species, with a very high share of endemic species.
Biodiversity Hotspots in India
- Western Ghats and Sri Lanka
- The Eastern Himalayas
- Indo-Burma Region
- Sundaland (South-East Asia region – India is represented by the Nicobar Islands)
- The Indo-Burma region encompasses several countries. It is spread out from Eastern Bangladesh to Malaysia and includes North-Eastern India south of Brahmaputra river, Myanmar, the southern part of China’s Yunnan province, Lao People’s Democratic Republic, Cambodia, Vietnam and Thailand.
- Sundaland is a region in South-East Asia that covers Thailand, Malaysia, Singapore, Brunei and Indonesia. India is represented by the Nicobar Islands.
Hottest Hotspots in the world
- Indo – Burma region
- Sundaland
- Philippines
- Western Ghats & Srilanka
- Madagascar
- Eastern arc & coastal forests of Tanzania/Kenya
- Caribbean island
- Brazil’s Atlantic forests
2010: International year for Biodiversity, declared by United Nations
22 May: International day for Biological diversity, declared by United Nations
India has only 2.4% of world land area & 4% of fresh water, yet accounts for 7.3% of recorded species making it 3rd most mega diverse country (after Brazil & Costa Rica) with highest concentration of species in Agasthymalai Hills in Western Ghats
Hope Spots
- A hope spot is an area of ocean that merits special protection because of its wildlife and significant underwater habitats.
- Andaman and Nicobar & Lakshadweep Islands have been named as the new “hope spots” by IUCN & oceanographer Sylvia Earle of Mission Blue, an organization involved in the study of oceans
- Andamans & Nicobar Island has some of world’s unique species of birds and plants.
- In the case of Lakshadweep, the coral reefs are quite sensitive to the ocean environment and that needs protection.