BSC 2011 Lecture Notes - Lecture 30: Ecological Island, Biogeography, Robert Macarthur
8 Dec 2016
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Document Summary
Species richness generally increases towards the equator: especially seen in rainforests of the tropics, seen in a variety of species: Latitudinal gradient: the observation that there are more species along the equator. Main climatic factors associated with biodiversity: solar energy input and water availability. Correlation between the two are positively related. The more heat and water causes more evapotranspiration. Three hypotheses for why there is more speciation at the equator: ecological limits hypothesis. In the tropics, there is more productivity and energy in the system that can support more individuals and populations. In more northern climates there is less energy and therefore less individuals can be supported: evolutionary rates hypothesis. The rate of speciation is higher in the tropics because mutations of species are more common. The resources needed for speciation are the same, but they are better managed in tropical climates. Physiological processes and mutations are increased in warmer temperatures: history hypothesis.
