Understanding Biodiversity: Definition and Levels

Definition of Biodiversity

• Biodiversity is a contraction of "biological diversity"
• Edward O. Wilson first coined the term biodiversity in 1986
• Biodiversity is a vast concept referring to the range of variations or differences among some set of entities
• Biological diversity refers to varieties within the living world
• The term 'biodiversity' is considered an 'Umbrella term' referring to organisms found within the living world
• It is commonly used to describe the number, variety of life, and variability of living organisms
• Biodiversity encompasses variability among living organisms from all sources, including terrestrial, marine, and aquatic ecosystems
• It includes diversity within species, between species, and of ecosystems

Levels and Elements of Biodiversity

• Biodiversity is considered on three fundamental hierarchical levels of biological organization: genes, species, and ecosystems
• These are referred to as genetic, species, and ecosystem diversity
• The predicted number of total species varies from 5 to 50 million, averaging at 14 million
• About 60% of all known species are insects
• About 16% are higher plants
• Only about 0.3% are mammals
• Sometimes landscape diversity, or pattern diversity, is considered a fourth type of biodiversity

Genetic Diversity

• Landscape can be a heterogeneous land area composed of a cluster of interacting ecosystems
• Genetic diversity is diversity within a species
• Species diversity is diversity between species, also know as taxonomic or organismal diversity
• Ecosystem or ecological diversity occurs at the ecological or habitat level
• Interaction is the principal intrinsic mechanism shaping the characteristics and functions of biodiversity
• These interactions are hierarchical in nature
• Genetic diversity is diversity within a species or infra-species diversity
• It encompasses the genetic coding that structures organisms, including nucleotides, genes, and chromosomes
• This includes variation in the genetic makeup between individuals within a population and between populations
• Variation can occur in alleles, entire genes, or chromosomal structures
• Genetic diversity enables a population to adapt to its environment and respond to natural selection

Measurement and Importance of Genetic Diversity

• If a species has more genetic diversity, it can adapt to changed environmental conditions
• Lower diversity in a species leads to uniformity
• The amount of genetic variation is the basis of speciation.
• Genetic diversity has a key role in maintaining diversity at species levels
• Genetic diversity within a species often increases with environmental variability
• It can be measured using DNA markers like RFLP, PCR, RAPD, APPCR, PFGE, and microsatellite-primed PCR

Species Diversity

• Species constitute distinct units of diversity, each playing a specific role in an ecosystem
• Loss of species has consequences for the ecosystem as a whole
• Species diversity refers to the variety of living species within a geographic area
• It encompasses the taxonomic hierarchy and its components, from individuals upwards to genera
• Simplest measures of species diversity include species richness (number of species per unit area) and species evenness (evenness in number of individuals of each species)
• Greater species richness generally correlates with greater species diversity

Alpha, Beta and Gamma Diversity

• Alpha diversity refers to the average species diversity within a particular area, habitat, community, or ecosystem
• Alpha diversity is measured by counting the number of taxa (distinct groups of organisms) within the ecosystem
• Beta diversity is species diversity between ecosystems
• It refers to the ratio between alpha diversity and regional diversity or comparison of taxa that are unique to each ecosystem
• Beta diversity calculated as the number of species in Habitat 1 minus the number of common species in Habitats 2 and 1, plus the number of species in Habitat 2 minus the number of common species in Habitats 1 and 2
• Gamma diversity is the overall diversity for different ecosystems within a region or total diversity over a large area or region

Uses of Biodiversity

• Direct-use values of biodiversity include food, medicine, biological control, industrial materials, recreational harvesting, and ecotourism
• Food can come in the form of vegetables, fruit, nuts, meat, milk, and food colorants, flavorings, and preservatives
• Medicines include willow trees (salicylic acid/aspirin), foxglove (digitoxin), Atropa belladonna (atropine), Opium sativum (codeine), Papaver somniferum (morphine), and Cinchona ledgeriana (quinine)
• Animal-sourced products include anticoagulants, coagulants, and vasodilator agents
• Animals are also used as models on which to test potentially useful drugs or techniques
• Biological control involves vector control using biological agents
• Industrial materials include building materials, fibers, dyes, resins, gums, adhesives, rubber, oils, waxes, agricultural chemicals (including pesticides), and perfumes
• Recreational harvesting involves harvesting animals (e.g., fish, reptiles, birds, mammals) for display and as pets

Threats to Biodiversity

• Global change in factors responsible for biodiversity results in loss of biodiversity
• These factors include land conversion, greater climatic changes & global warming, pollution, exploitation of natural resources, interference of ecosystems by alien species, habitat destruction, and genetic manipulation of species

Secondary Causes of Biodiversity Loss

• Population growth
• Unsustainable patterns of consumptions
• Increased waste production
• Urban development
• International conflict

Mega-Biodiversity and Biodiversity Hotspots

• The distribution of biological species across the world differs, with some areas having an abundance of life and others having very little
• A mega-diversity zone is defined as a region with a large number of species in an ecosystem
• The concept of biodiversity hotspots was developed by Norman Myers in 1988
• Hotspots are the richest and the most threatened reservoirs of plant and animal life on Earth
• There are 34 hotspots for conservation of biodiversity, which have been identified worldwide, including four Indian hotspots

Conservation of Biodiversity

• Conservation is defined as management of human use of the biosphere to yield sustainable benefit to the present generation while maintaining its potential to meet the needs and aspirations of posterity
• Two basic strategies for biodiversity conservation are in-situ (on-site) and ex-situ (off-site) conservation

In-situ Conservation

• Conservation of organisms in their natural home is achieved through protection of typical ecosystems via a network of protected areas, biosphere reserves, sacred forests, and sacred lakes
• Protected areas, such as National Parks and Wildlife Sanctuaries, are areas of land and/or sea especially dedicated to protecting and maintaining biological diversity, and natural and associated cultural resources
• There are more than 37,000 protected areas around the world
• India has 612 protected areas, including 99 National Parks and 513 Wildlife Sanctuaries

Biosphere Reserves

• Biosphere reserves are a special category of protected areas of land and/or coastal environments wherein people are an integral component of the system
• A biosphere reserve consists of core, buffer, and transition zones
• The core zone comprises an undisturbed and legally protected ecosystem
• The buffer zone surrounds the core area and is managed to accommodate a greater variety of resource use strategies, research, and educational activities
• The transition zone is the outermost part of the biosphere reserve and is an area of active cooperation between reserve management and local people
• Some activites that take place are settlements, cropping, forestry, and recreation and other economic uses continue in harmony with conservation goals
• There are 408 biosphere reserves located in different countries and 13 reserves are located in India.

Ex-situ Conservation

• Utilizes botanical gardens, zoos, conservation stands, gene, pollen, seed, seedling, tissue culture and DNA banks to protect species
• There are more than 1,500 botanical gardens worldwide with >80,000 species
• Many botanical gardens now have seed banks, tissue culture facilities, and other ex-situ technologies
• More than 800 professionally managed zoos worldwide contain about 3,000 species of mammals, birds, reptiles, and amphibians
• Plants and animals conserved in botanical gardens, arboreta, zoos and aquaria can be used to restore degraded land, reintroduce species into the wild, and restock depleted populations

Biodiversity in India

• India is known for its biodiversity
• India is one of the 17 mega-diverse countries in the world with 7-8% of the world's recorded plant and animal species
• 91,307 species of animals (2,557 Protista), 12,470 general invertebrates, 69,903 arthropods, 4,994 vertebrates, and 45,500 species of plants and 5,650 microbial species have been documented in India
• About 5,150 plant species and 1,837 animal species are endemic to India
• India possesses cultural and traditional diversity including 550 tribal communities of 227 traditional groups across 5,000 forested villages