The primary cause of loss of biodiversity is --------------------.

The accelerated rates of species extinctions that the world is facing now are largely due to human activities. There are four major causes, known as the 'Evil Quartet'.

Habitat loss and fragmentation is the most important and primary cause driving animals and plants to extinction. The most dramatic examples of habitat loss come from tropical rain forests.

Other causes include overexploitation, alien species invasions, and co-extinctions, but habitat loss remains the primary factor.

Answer: Habitat loss and fragmentation