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 overexploitation 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 3^rd 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.