a. ‘The Evil Quartet’ describes the rates of species extinction due to human activities. Explain how the population of organisms is affected by fragmentation the habitats. b. Introduction of alien species has led to environmental damage and decline of indigenous species. Give any one example of how it has affected the indigenous species? c. Could the extinction of Steller’s sea cow and passenger pigeon be saved by man? Give reasons to support your answer.

a. ‘The Evil Quartet’ describes the rates of species extinction due to human activities. Explain how the population of organisms is affected by fragmentation the habitats.
b. Introduction of alien species has led to environmental damage and decline of indigenous species. Give any one example of how it has affected the indigenous species?
c. Could the extinction of Steller’s sea cow and passenger pigeon be saved by man? Give reasons to support your answer.

Answer.
a. When a large habitat is broken into small fragments due to various
activities, mammals and birds requiring large territories and certain
animals with migratory habitats are badly affected, leading to
population decline.
b.
● Nile perch introduced in Lake Victoria eventually led to the
extinction of an ecologically unique assemblage of more than
200 species of cichild fish.
● Parthenium/Lantana/water hyacinth caused environmental
damage and threat to our native species
● African catfish-Clarias gariepinus introduced for aquaculture
purposes is posing a threat to the indigenous catfishes in our
rivers. (Any one)
c. Yes; Humans have overexploited natural resources for their ‘greed’
rather than ‘need’ leading to extinction of these animals.
Sustainable harvesting could have prevented extinction of these
species.