Biodiversity as the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part. This includes diversity within species, between species and ecosystems of a region.

Habitat fragmentation is the process where a large, continuous area of habitat is both, reduced in area and divided into two or more fragments.
Eg. Fragmentation of habitats like forest land into crop lands, orchard lands, plantations, urban areas, industrial estates

Species diversity refers to the variety in number and richness of the species in any habitat.

(i) The chemical found in the medicinal plant Rauwolfia vomitoria is reserpine.
(ii) It belong to Genetic diversity.

There are three levels of biodiversity are
(1) Genetic diversity
(2) Species diversity and
(3) Community / Ecosystem diversity

Endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere.

It is a natural habitat that is notified by the state government to be constituted as a National Park due to its ecological, faunal, floral, geomorphological or zoological association of importance. No human activity is permitted inside the national park except the activities permitted by the Chief Wildlife Warden.
Eg: Mudumalia National park in Nilgiris district

The non-native or alien species of organisms are called exotic species. They are introduced unintentionally or deliberately as biological control agents for or other uses.
Eg .Tilapia fish from East African Coast has been introduced into Kerala's inland water for its high productivity.

Even though India is one of the 17 identified megadiverse countries of the world, it faces lots of threats to its biodiversity.
(i) Apart from natural causes, human activities, both directly and indirectly are today's main reason for habitat loss and biodiversity loss.
(ii) Fragmentation and degradation due to agricultural practices, extraction (mining, fishing, logging, harvesting) and development (settlements, industrial and associated infrastructures) lead to habitat loss and fragmentation leads to the formation of isolated, small and scattered populations and as endangered species.

Biodiversity is the variety of life on earth. That is, it is the number of different species of flora and fauna including microorganisms. These organisms can inhabit different ecosystems with, varying conditions like the Rainforests, Coral reefs, Grasslands, Deserts, Tundra, and the Polar icecaps. This variety (Biodiversity) is essential for the wellbeing of our planet and sustenance of life as a whole. The importance of biodiversity can be viewed and measured as:
a)Ecosystem services
b) Biological resources
c) Social benefits of biodiversity
The organization and functioning of ecosystems world over are affected and dependent on biodiversity and its richness. The major functional attributes are:
(i) Continuity of nutrient cycles or biogeochemical cycles (N₂, C, a,o, P, S cycles)
(ii) Soil formation, conditioning or maintenance of soil health (fertility) by soil microbial diversity along with the different trophic members
(iii) Increases ecosystem productivity and provide food resources
(iv) Act as water traps, filters, water flow regulators and water purifiers (forest cover and vegetation)
(v) Climate stability (forests are essential for rainfall, temperature regulation, CO₂ absorption, which in turn regulate the density and type of vegetation)
(vi) Forest resource management and sustainable development
(vii) Maintaining a balance between biotic components
(viii) Cleaning up of pollutants - microbes are the biggest degraders of molecules including many anthropogenic ones which are present in effluents, sewage, garbage and agro-chemicals
(ix) Ecological stability - the varieties and richness of species contribute to ecological stability and survival of species. Biodiverse regions are reservoirs of biological resources like food resources, gene pool, genetic resource, medicinal resources, bioprospecting
(x) To provide unique aesthetic value and hotspots for Ecotourism. Along with forest resources and wildlife, it has commercial significance
(xi) An indicator of the health of the ecosystem. Endemism is a crucial indicator of richness.

(i) Development of human society is inevitable. Natural habitats are destroyed for the purpose of settlement, agriculture, mining, Industries and construction of highways
(ii) As a result species are forced to adapt to the changes in the environment or move to other places. If not, they become victim to predation, starvation, disease and eventually die or results in human animal conflict.
(iii) Over population, urbanization, Industrialization and agricultural advancements require additional land, water and raw materials every year.
(iv) This is made possible only through fragmentation or destruction of natural habitats by filling wetlands, ploughing grasslands, cutting down trees, forest, desilting rivers, constructing transport ways, caving mountains, extracting, ores, changing the course of rivers and filling of seashore.

Insitu and Exsitu are two types of biodiversity conservation strategies.

S. No	Insitu Conservation	Exsitu Conservation
i)	It is the on-site conservation or the conservation of genetic resources in natural populations of plant or animal species.	This is a conservation strategy which involves placing of threatened animals and plants in special care locations for their protection.
ii)	It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or restoring the habitat itself or by defending the species from predators.	It helps in recovering populations or preventing their extinction under simulated conditions that closely resemble their natural habitats.
iii)	National Parks, Biosphere Reserve, Wild Life Sanctuaries form insitu conservation strategies.	Zoological parks and Botanical gardens are common exsitu conservation programs.

(i) Keystone species are those which have an extremely high impact on a particular ecosystem relative to its population. They are critical for the overall structure and function of an ecosystem and influence other and plants and animals that make up that ecosystem. Thus in the absence of a keystone species, many ecosystems will fail to exist.
(ii) Predator-prey relationship is an important example. Small Predators that consume herbivorous species prevent such herbivores from destroying the plant species in the ecosystem and are thus considered as keystone species.
(iii) If the number of predators was to decrease, the herbivore population would increase and the plant species in the ecosystem may perish very fast. In turn, the other organisms dependent on plants may also be impacted.
(iv) Thus extinction of a keystone species will lead to loss of biodiversity. Eg. Sea otter is considered to be a keystone species in the nearshore ecosystem. The Kelp forests are critical habitat for many organisms in nearshore ecosystems. These are fed by sea urchins. The Otters feed a Sea Urchins. In the absence of Otters, the sea urchins will destroy the Kelps forest which in turn will impact several other organisms and lead to loss of biodiversity in the ecosystem.

(i) Red Data Book or Red list is a catalogue of taxa facing risk of extinction.
(ii) IUCN - International Union of Conservation of Nature and Natural Resources
(iii) WCU - World Conservation Union maintains the Red Data Book.
(iv) The concept of Red list was mooted in 1963.
The purpose of preparation of Red List are:
(i) To create awareness on the degree of threat to biodiversity
(ii) Identification and documentation of species at high risk of extinction
(iii) Provide global index on declining biodiversity
(iv) Preparing conservation priorities and help in conservation of action
(v) Information on international agreements on conservation of biological diversity
Red list has eight categories of species:
(i) Extinct
(ii) Extinct in wild
(iii) Critically Endangered
(iv) Endangered
(v) Vulnerable
(vi) Lower risk
(vii) Data deficiency
(viii) Not evaluated.

The major causes for biodiversity decline are:
(i) Habitat loss, fragmentation, and destruction (affects about 73% of all species)
(ii) Pollution and pollutants (smog, pesticides, herbicides, oil slicks, GHGs)
(iii) Climate change
(iv) Introduction of alien/exotic, species.
(v) Over exploitation of resources (poaching, indiscriminate cutting of trees, overfishing, hunting, mining).
(vi) Intensive agriculture and aquacultural practices.
(vii) Hybridization between native and nonnative species and loss of native species
(viii) Natural disasters (Tsunami, forest fire, earthquake, volcanoes).
(ix) Industrialization, Urbanization, infrastructure development, Transport - Road and Shipping activity, communication towers, dam construction, unregulated tourism, and monoculture are a common area of specific threats.
(x) Co-extinction.