The introduction of Nile perch into Lake Victoria in East Africa led to the extinction of more than 200 species of cichlid fish in the lake. This is an example of:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Alien species invasions
The four major causes of loss of biodiversity are called “The Evil Quartet”: habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions. An alien species is one brought into an area from outside. Some such species turn invasive and cause the decline or extinction of the native (indigenous) species. The Nile perch put into Lake Victoria ate up more than 200 species of cichlid fish found only there.
(1) Endemism — Incorrect. Endemism means a species is found only in one area and nowhere else. It is not a cause of extinction.
(2) Over-exploitation — Incorrect. Over-exploitation is too much harvesting of a species by humans, as with the Steller’s sea cow and the passenger pigeon. The cichlids were not over-harvested.
(3) Co-extinctions — Incorrect. In co-extinction, when one species dies out, the species tied to it (such as its parasites or its pollinator partner) die out too.
(4) Alien species invasions — Correct. The Nile perch was an introduced species that turned invasive.
NCERT Extract:
Loss of Biodiversity – “… (iii) Alien species invasions: When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction of indigenous species.”
