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Unformatted text preview: Evolution, Biological Communities, and Species Interactions Definitions evolution - genetic changes within a population over time natural selection - differential reproductive success mutations - random changes o in DNA adaptation - genetic trait that confers a selective advantage in a given environment Limits All living things have limits to the environmental conditions under which they can survive. Critical Limits Von Liebig proposed the single factor in shortest supply relative to demand is the critical determinant in species distribution. Shelford later expanded by stating each environmental factor has both minimum and maximum levels, tolerance limits, beyond which a particular species cannot survive. Tolerance Limits Critical Limits For many species, the interaction of several factors, rather than a single limiting factor, determines biogeographical distribution. For some organisms, there may be a specific critical factor that mostly determines abundance and distribution. Species requirements and tolerances can also be used as useful indicators....
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