Review the major hypotheses proposed to explain the higher species richness of t

The time since perturbation hypothesis suggests tropical regions have less disturbance and therefore lower extinction rates. The productivity hypothesis suggests tropical regions have greater primary production, and therefore larger population sizes and lower extinction rates for sensitive species. The environmental heterogeneity hypothesis states that tropical regions are more variable, and can therefore support a greater range of species. In contrast, the favourableness hypothesis suggests that tropical regions have fewer abiotic extremes (i.e. in temperature) and are therefore suitable for a wider range of species. The niche breadth hypotheses present several explanations related to species interactions.