The tropics show the greatest levels of species richness because of the following reasons:
Speciation: The tropics have been left undisturbed for several years that led to the evolution of several species as compared to the species in the temperate regions.
Environment: The environment is more predictable, constant and less seasonal. This provides an opportunity to a large number of species to flourish which leads to species richness.
Solar energy: More solar energy increases productivity and in turn increases the diversity.
