Theories to Explain High Diversity in the Tropics

The question, Why are there so many species in the tropics is one that has intrigued scientists for almost a century. Scores of theories have been put forth to account for the increase in diversity in almost all taxa along a gradient of decreasing latitude. Pianka (1966) reviewed the major theories of the time and lumped them into six categories the time theory the theory of climatic stability the theory of spatial heterogeneity the competition hypothesis the predation hypothesis and the...