(i) Alpha diversity: It is measured by counting the number of taxa (usually species) within a particular area, community or ecosystem.
(ii) Beta diversity: It is species diversity between two adjacent ecosystems and is obtaining by comparing the number of species unique to each of the ecosystem.

Habitat fragmentation is the process where a large, continuous area of habitat is both, reduced in area and divided into two or more fragments. Fragmentation of habitats like forest land into crop lands, orchard lands, plantations, urban areas, industrial estates, transport and transit systems has resulted in the destruction of complex interactions amongst species, (food chain and webs) destruction of species in the cleared regions, annihilation of species restricted to these habitats (endemic) and decreased biodiversity in the habitat fragments. Animals requiring large territories such as mammals and birds are severely affected. The elephant corridors and migratory routes are highly vulnerable. The dwindling of-many well-known birds (sparrows) and animals can be attributed to this.

The most serious aspect of the loss of biodiversity is the extinction of species. The unique information contained in its genetic material (DNA), and the niche it possesses are lost forever.

Hotspots are areas characterized with high concentration of endemic species experiencing unusual rapid rate of habitat modification loss.
Eg. Western Ghats in India

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.