BIOL 3130 Lecture Notes - Lecture 8: Disruptive Selection, Primary Production, Competitive Exclusion Principle
27 Oct 2017
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Area is important but cannot be the only factor. The maintenance of diversity: the factors that determine the relative balance of species arrivals and species extinctions. Assumption: greater long-term stability aids the accumulation of species over time, with less perturbation meaning less extinction. Temperate systems of the north and south, by contrast, have experienced several major disturbances relating to glaciation over the past 2-3my. More time permits more complete range colonization and more evolution of new species. Support: tropics-free from glaciation, speciation takes time (evolution); dispersal takes time (ecology) Problem: no region of the planet was free from the effects of glaciation. Glaciation: the tropics were more disrupted than originally believed (drought, fire, expansion of savannah-moisture locked up in glaciers: disturbance hypothesis. Current understanding: disturbances can be a mechanism of speciation (evolution), and a mechanism maintain diversity by offsetting competitive exclusion (ecology)
