Which of the following is not the cause of biodiversity loss?

The correct answer is Option (3) → Endemism

The four major causes of biodiversity loss are called ‘The Evil Quartet’: habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions.

Option (1) Co-Extinction — A cause of biodiversity loss. When a species dies out, the species tied to it in an obligatory way, such as its parasites, die out too.

Option (2) Over-exploitation — A cause of biodiversity loss. Too much harvesting drove Steller’s sea cow and the passenger pigeon to extinction.

Option (3) Endemism — Not a cause of biodiversity loss. Endemism means species found only in one region. High endemism marks a biodiversity hotspot; it is a feature of rich regions, not a cause of loss.

Option (4) Alien species invasions — A cause of biodiversity loss. Introduced species such as the Nile perch can wipe out native species.

NCERT Extract:
Loss of Biodiversity – “In general, loss of biodiversity in a region may lead to (a) decline in plant production, (b) lowered resistance to environmental perturbations such as drought and (c) increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycles. Causes of biodiversity losses: The accelerated rates of species extinctions that the world is facing now are largely due to human activities. There are four major causes (‘ The Evil Quartet ’ is the sobriquet used to describe them).”
Loss of Biodiversity – “… (ii) Over-exploitation: Humans have always depended on nature for food and shelter, but when ‘need’ turns to ‘greed’, it leads to over-exploitation of natural resources.”
How Do We Conserve Biodiversity? – “… On a global basis, this problem has been addressed by eminent conservationists. They identified for maximum protection certain ‘biodiversity hotspots’ regions with very high levels of species richness and high degree of endemism (that is, species confined to that region and not found anywhere else).”