One of the following statements is incorrect with reference to biodiversity. Identify it:
1. The richest reservoirs of animal and plant life (high species richness) with few or no threatened species are called 'biodiversity hotspots’
2. Biodiversity increases from higher altitudes to lower altitudes
3. Biodiversity decreases from the equator to polar regions
4. Depletion in genetic diversity of crop plants is mainly due to the introduction of better varieties with high yield, disease resistance, etc.