A quick guide to Biodiversity
Biodiversity, a contraction of “Biological diversity”, generally refers to the variety and variability of life on Earth. One of the most widely used definitions defines it in terms of the variability within species, between species and between ecosystems. It is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation within an area, biome, or planet.
Terrestrial biodiversity tends to be greater near the equator, which seems to be the result of the warm climate and high primary productivity. Biodiversity is not distributed evenly on Earth and is richest in the tropics. These tropical forest ecosystems cover less than 10% of earth’s surface and contain about 90 percent of the world’s species.
Types of Biodiversity
Each member of any animal or plant species differs widely from other individuals in its genetic makeup because of a large number of combinations possible in the genes that give every individual specific characteristic. Thus, for example, each human being is very different from all others.
This genetic variability is essential for a healthy breeding population of a species. If the number of breeding individuals is reduced, the dissimilarity of genetic makeup is reduced and in-breeding occurs. The diversity in wild species forms the ‘gene pool’ from which our crops and domestic animals have been developed over thousands of years.
This diversity is seen both in natural ecosystems and in agricultural ecosystems. Some areas are richer in species than others. Natural undisturbed tropical forests have much greater species richness than plantations. A natural forest ecosystem provides a large number of non-wood products that local people depend on such as fruit, fuelwood, fodder, fiber, gum, resin, and medicines. At present conservation, scientists have been able to identify and categorize about 1.75 million species on earth.
There are a large variety of different ecosystems on earth, which have their own complement of distinctive interlinked species based on the differences in the habitat. Ecosystem diversity can be described for a specific geographical region, or a political entity such as a country, a state or a taluka.
Distinctive ecosystems include landscapes such as forests, grasslands, deserts, mountains, etc., as well as aquatic ecosystems such as rivers, lakes, and the sea. Ecosystems are most natural in wilderness areas. If natural ecosystems are overused or misused their productivity eventually decreases and they are then said to be degraded. India is exceptionally rich in ecosystem diversity.
Ecosystem Diversity can be further classified into 3 sub-categories.
- Alpha Diversity;
It is the biodiversity of a particular area, community or ecosystem. It is usually expressed by the number of species (i.e., species richness) in that ecosystem. This can be measured by counting the number of taxa (distinct groups of organisms) within the ecosystem (e.g., families, genera, and species).
- Beta Diversity;
It is a measure of biodiversity which works by comparing the species diversity between ecosystems or along environmental gradients. This involves comparing the number of taxa that are unique to each of the ecosystems. It is the rate of change in species composition across habitats or among communities. It gives a quantitative measure of diversity of communities that experience changing environments.
- Gamma Diversity;
It refers to the total species richness over a large area or region. It is a measure of the overall diversity of the different ecosystems within a region. It is the product of a diversity of component ecosystems and the P diversity between component ecosystems.
Gamma diversity (Mathematical representation)
Gamma diversity can be expressed in terms of the species richness of component communities
Y = S1 + S2 – C
S1 = Total number of species recorded in the first community.
S2 = Total number of species recorded in the second community.
C = Number of species common to both communities.
A biodiversity hotspot is a region with a high level of endemic species that have experienced great habitat loss. While hotspots are spread all over the world, the majority of which are forest areas and most are located in the tropics.
To qualify as a biodiversity hotspot on Myers 2000 edition of the hotspot-map, a region must meet two strict criteria:
- It must contain at least 0.5% or 1,500 species of vascular plants as
- It has to have lost at least 70% of its primary vegetation.
Brazil‘s Atlantic Forest is considered one such hotspot, containing roughly 20,000 plant species, 1,350 vertebrates and millions of insects, about half of which occur nowhere else. The island of Madagascar and India are also particularly notable.
Colombia is characterized by high biodiversity, with the highest rate of species by area unit worldwide and it has the largest number of endemics of any country. About 10% of the species of the Earth can be found in Colombia.
- Amazon Rainforest
- Atlantic Forest (Brazil)
- Caribbean Islands
- The Western Ghats, Eastern Himalaya (India)
- Ganga-Brahmaputra Delta (India-Bangladesh)
- Mediterranean Basin (Europe)
Threats to Biodiversity
Rising population growth and resource consumption, climate change, and global warming, habitat conversion, and urbanization, invasive alien species, over-exploitation of natural resources and environmental degradation have put our Biodiversity under serious threat. Human activities have caused destruction and fragmentation of natural habitats, pollution, and eutrophication caused by agricultural and industrial practices, excessive water catchments in some areas, climate change, overfishing or sand and gravel extraction in marine areas.
International lists for threatened species
Species often become threatened or disappear when several of these factors are combined. The fragmentation of habitats decreases the size of populations and make these more vulnerable to other factors. Once the population is weakened, small external perturbations such as disease can wipe out the remaining individuals entirely. Thus the IUCN Red List and Red Data Books were laid down to identify, categorize and provide priority preservation to threatened species around the world.
IUCN Red List
The IUCN Red List of Threatened Species, founded in 1964, is the world’s most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature (IUCN) is the world’s main authority on the conservation status of species. A series of Regional Red Lists are produced by countries or organizations, which assess the risk of extinction to species within a political management unit.
The IUCN Red List is set upon precise criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world. The IUCN aims to have the category of every species re-evaluated every five years if possible, or at least every ten years.
The Red List of 2012 was released 19 July 2012 at Rio+20 Earth Summit; nearly 2,000 species were added, with 4 species to the extinct list, 2 to the rediscovered list. The IUCN assessed a total of 63,837 species which revealed 19,817 are threatened with extinction. With 3,947 described as “critically endangered” and 5,766 as “endangered”, while more than 10,000 species are listed as “vulnerable”.
Red Data Book
Red Data Book of the Russian Federation (RDBRF), is a state document established for documenting rare and endangered species of animals, plants, and fungi, as well as some local subspecies that exist within the territory of the Russian Federation and its continental shelf and marine economic zone. The book has been adopted by Russia and all CIS states to enact a common agreement on rare and endangered species protection.
The book provides a central information source in organizing studies and monitoring programs on rare and endangered species and their habitats. It is regularly consulted when developing and implementing special measures for the protection and rehabilitation of such species.
- Ankita Bhatia
- Arijit Samajdar
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