Shankar IAS Summary: Biodiversity- 2 | Famous Books for UPSC Exam (Summary & Tests) PDF Download

(a) Extinct (EX)

• A taxon is deemed Extinct when there is no reasonable doubt that the last individual has perished.
• It is presumed Extinct when exhaustive surveys throughout its historical range, at all appropriate times, have failed to document an individual.

(b) Extinct in the Wild (EW)

• A taxon is classified as Extinct in the Wild when it is only known to survive in cultivation, captivity, or as a naturalized population well beyond its historical range.

It is presumed Extinct in the wild when thorough surveys within known and expected habitats, at appropriate times, throughout its historical range have been unsuccessful in recording an individual.

Great India Bustard (Critically Endangered)

(c) Critically Endangered (CR)

• A taxon attains the status of Critically Endangered when the best available evidence indicates that it meets any of the criteria for Critically Endangered.
• Criteria include a reduction in population (>90% over the last 10 years), a population size of fewer than 50 mature individuals, and a quantitative analysis showing a probability of extinction in the wild of at least 50% within 10 years.

(d) Endangered (EN):

• A taxon is labeled Endangered when the best available evidence indicates that it meets any of the criteria for Endangered.
• Criteria involve a reduction in population size (70% over the last 10 years), a population size estimated to be fewer than 250 mature individuals, and a quantitative analysis showing a probability of extinction in the wild of at least 20% within 20 years.

Vulnerable Species

(e) Vulnerable (VU)

• A taxon is identified as Vulnerable when the best available evidence suggests that it meets any of the criteria for Vulnerable.
• Criteria include a reduction in population (>50% over the last 10 years), a population size estimated to be fewer than 10,000 mature individuals, and a probability of extinction in the wild of at least 10% within 100 years.

(f) Near Threatened (NT)

• A taxon is categorized as Near Threatened when evaluated against the criteria but does not currently qualify for Critically Endangered, Endangered, or Vulnerable. It is close to qualifying for or is likely to qualify for a threatened category shortly.

(g) Least Concern (LC)

• A taxon is considered Least Concern when evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable, or Near Threatened. This category includes widespread and abundant taxa.

Least-Concern

(h) Data Deficient (DD)

• A taxon is labeled Data Deficient when there is insufficient information to make a direct or indirect assessment of its risk of extinction based on distribution and population status. This category indicates the need for more information and is not a threat classification.

(i) Not Evaluated (NE)

• A taxon is categorized as Not Evaluated when it has not yet been assessed against the criteria, and its conservation status remains undetermined.

Important Species in Ecosystem