Biodiversity and Extinction

• Biodiversity exists not only at the species level but also at all levels ranging from macromolecules within cells to biomes.
• Sociobiologist Edward Wilson popularized the term biodiversity.

Biodiversity Levels

• Genetic diversity: A single species might show high diversity at the genetic level over its distributional range.
• Genetic variation is demonstrated by the medicinal plant Rauwolfia vomitoria in the Himalayas, which varies in the potency and concentration of the active chemical reserpine.
• India has over 50,000 genetically different rice strains and 1,000 mango varieties.
• Species diversity: The Western Ghats have greater amphibian species diversity compared to the Eastern Ghats.
• Ecological diversity: At the ecosystem level, India has a greater ecosystem diversity than a Scandinavian country like Norway, due to its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows.

Species Numbers

• According to the IUCN (2004), slightly more than 1.5 million plant and animal species have been described.
• Species inventories are more complete in temperate regions than in tropical countries.
• A conservative and scientifically sound estimate by Robert May places global species diversity at about 7 million.
• Animals account for over 70% of recorded species, while all plants account for no more than 22% of the total.
• Insects are the most species-rich taxonomic group among animals, making up over 70% of the total.
• The number of fungi species surpasses the combined total of fish, amphibian, reptile, and mammal species.
• Conventional taxonomic methods are not suitable for identifying microbial species, and most are unculturable under laboratory conditions.

India's Biodiversity

• India possesses only 2.4% of the world's land area, but it contributes an impressive 8.1% of global species diversity.
• India is one of the 12 mega diversity countries in the world. Approximately 45,000 plant species and twice as many animal species have been recorded in India.
• Applying May's global estimates, it's estimated that over 100,000 plant species and over 300,000 animal species are yet to be discovered and described in India

Latitudinal Gradients

• Tropics (23.5° N to 23.5° S) harbor more species than temperate or polar areas.
• Colombia, near the equator, has about 1,400 bird species, whereas New York (41° N) has 105 species, and Greenland (71° N) has only 56 species.
• Forests in tropical regions have up to 10 times as many vascular plant species as forests in temperate regions.
• The largely tropical Amazonian rain forest in South America boasts the earth's greatest biodiversity.
• Tropical latitudes have remained relatively undisturbed for millions of years, allowing for speciation. They also possess less seasonal and more constant environments and higher solar energy.

Species-Area Relationships

• Alexander von Humboldt observed that species richness increases within a region with the increasing explored area but up to a certain limit
• The relationship between species richness and area for various taxa turns out to be a rectangular hyperbola. log S = log C + Z log A S = Species richness A = Area Z = slope of the line (regression coefficient) C = Y-intercept
• The value of Z lies in the range of 0.1 to 0.2, whether it refers to plants in Britain, birds in California, or mollusks in New York state.
• Z values can be in the range of 0.6 to 1.2 if analyzing the species-area relationships among very large areas, such as entire continents.

Species Diversity and Ecosystem Stability

• Communities with more species generally tend to be more stable than those with fewer species.
• A stable community displays minor productivity variation year after year, resists disturbances, either natural or man-made, and repels alien species' invasions.
• David Tilman's experiments revealed that plots with more species had less year-to- year variation in total biomass, and higher diversity contributed to greater productivity.
• Stanford ecologist Paul Ehrlich used the "rivet popper hypothesis" to explain the importance of each species.
• The loss of rivets on the wings represents key species driving major ecosystem functions, posing a more significant risk to flight safety as opposed to losing a few rivets on the seats or windows inside the plane.

Biodiversity Loss

• While new species addition through speciation remains uncertain, existing species face continuous losses, primarily attributed to human activities.
• Colonization of tropical Pacific Islands by humans led to the extinction of over 2,000 native bird species.
• The IUCN Red List (2004) records the extinction of 784 species, Last recorded within 500 years, in particular vertebrates, invertebrates, and plants.
• Recent extinctions include the dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller's Sea Cow (Russia), and three tiger subspecies.
• In the last twenty years, 27 species went extinct, highlighting an accelerating trend.

Threats to Biodiversity

• Extinctions are not arbitrary
• Some groups, such as amphibians, are especially prone to extinction.
• 12% of bird species, 23% of mammal species, 32% of amphibian species, and 31% of gymnosperm species are currently threatened with extinction.
• There have been five episodes of mass extinction on Earth.
• The sixth extinction currently in progress is estimated to be 100 to 1,000 times faster than in pre-human times.

Factors Causing biodiversity downfall:

• declining Plant Productivity
• Loss of Biodiversity in a region may lead to lowered resistance to environmental perturbations
• Increased variability in certain ecosystem process
• Habitat loss and fragmentation: driving animals and plants to extinction.
• Tropical rain forests have decreased from over 14% to no more than 6% cover. The Amazon rain forest is being cut and cleared for cultivating soya beans or for conversion to grasslands for raising beef cattle
• Mammals and birds require large territories, and animals with migratory habits are badly affected when large habitats get broken up into small fragments resulting in population decline.
• Over-exploitation: Humans exploitation of nature for food and shelter Steller's sea cow and passenger pigeon extinctions were due to overexploitation by humans.
• Alien species invasions: When alien species are introduced, leading to the decline or extinction of indigenous species.
• The Nile perch that was introduced into Lake Victoria in East Africa, leading to the extinction of over 200 cichlid fish species.
• Co-extinctions: When a species becomes extinct, the plant and animal species that were once associated with it in an obligatory way end up extinct.

Biodiversity Conservation

• There are three categories: narrowly utilitarian, broadly utilitarian, and ethical.
• Narrowly utilitarian: direct economic benefits
• More than 25% of drugs sold in the worldwide market derived from plants
• 25,000 contribute to traditional medicines used by native peoples around the world.
• Broadly utilitarian: Biodiversity has a major role in the service that nature provides.
• Pollination is just one example where without plants no oxygen would be produced in their processes.
• Ethical; every species has the right to exist and play a role. Its our duty to preserve species.

Approaches to Conservation

• In situ (on site) conservation protects the whole ecosystem to save biodiversity at all levels,
• Ex situ (off site) conservation saves species through urgent measures to prevent them From going extinct .
• Biodiversity hotspots are regions that have been identified for extreme protection with maximum species richness and degrees of endemism. In the region if it is not found anywhere else.
• Initially 25 biodiversity hotspots were identified but in today’s world they number 34 due to added additions.
• The Western Ghats + Srilanka , Indo Barma and Himalaya.
• These Regions Have some key features which included accelerated Habitat Loss. High levels of species and biodiversity richness. There is also a high decree of endemism meaning this species are only confined in this given region.
• These biodiversity hotspots together occupy just two percent of the Earth’s Land Area where a variety of species can be found.

Mass extinction and high rich species

• Ongoing Protection can result can lead to mass extinction to reduce at the minimum 30%.
• India has a wide variety that are protected regions such as 14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries.
• The earth summit has agreed in 2002 Johannesburg, South Africa a total of 100 countries has pledged their reduction in biodiversity loss.
• the World's biodiversity regions. Three key areas include the Western Ghats region in Sri Lanka of Indo Burma's Himalaya. And the sacred groves in Meghalaya, sacred Grove, are the last refuges for the large number of rare threatened plants.
• Sacred Groves can consist of zoological Parks, botanical gardens and a wildlife safari in the park located in Meghalaya

Methods conservation

• In X2 conservation threatened animals take come from their natural habitat and placed a special setting where the can have a protected region as such zoological parks, botanical gardens, and Wildlife Safari Parks.
• Now with modern technology that have advanced past maintaining threatened species in an enclosure we can now gametes can now we can use cable and federal condition.
• seeds of different general strains of commercially important can be kept for long periods in seed banks.
• all the other methods included protective maintenance of threatened species of zoological botanical gardens in fertilization and tissue culture of cryo preservation of gametes.
• World Summit on sustainable development in the follow up during the Earth's summit called the Convention on biological diversity was held in real January 1992 called on for nations to take of appropriate measures for conservator biodiversity.

Test your knowledge about biodiversity, endangered species, and extinction rates. Questions cover topics such as the IUCN Red List, current threats to organisms, genetic variety, and mass extinction events. See how much you know about the variety of life on Earth and the challenges it faces.