What is a common effect of habitat fragmentation on biodiversity?

• A. Fragmentation reduces species richness and gene flow.
• B. Fragmentation increases species richness.
• C. There is no impact on ecosystem services.
• D. It uniformly improves connectivity.

Answer: (A)

Breaking up a continuous habitat into smaller, isolated patches often reduces biodiversity. When habitats are fragmented, each patch becomes smaller and more isolated, so fewer species can be supported and local populations are more prone to extinction. The smaller the patch, the fewer individuals it contains, which lowers species richness directly. Isolation also curtails movement of individuals and their genes between patches, reducing gene flow and genetic diversity. That reduced genetic exchange weakens populations’ ability to adapt to changes and recover from disturbances, further eroding biodiversity over time. Edge effects or altered microclimates at patch boundaries can favor some species while harming others, shifting community composition and reinforcing the decline.

This contrasts with the idea that richness would increase, or that ecosystem services are unaffected, or that connectivity would improve. In reality, fragmentation disrupts connectivity and generally diminishes biodiversity and the resilience of ecosystems.