3. Give three hypotheses for explaining why tropics show greatest levels of species richness.
Tropics show the greatest level of species richness due to the following reasons (hypotheses)
1. The climate of tropical areas is more stable as compared to temperate areas. So the local populations, continuously live in the absence of natural disturbances.
2. Tropical communities are highly productive and can support a wide range of other species. This is mainly because tropics receive more solar energy.
3. In tropics, there is warm temperature and high humidity. Such conditions are favourable for a number of varieties of fungi, plants and algae.