BIO220H1 Lecture Notes - Lecture 7: Exponential Growth
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BIO220H1 Full Course Notes
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If rates are constant and if birth and immigration > death and emigration, then growth trajectory is density independent and exponential. The logistic model is the simplest model of density dependent models that takes disease etc into consideration. Extrapolation gave a poor prediction because: extrapolation is dangerous, this is not a law it is just a hypothesis, this allows no overshoots, this assumes r and k to be constant. Our current food production can support 2. 5 billion people if the patterns were similar to canada and the us. 10 billion people with food consumption patterns like india. Stage 1: birth and death rates both high, r = 0. Stage 2: death rates drop, birth rates stay high and the population booms. Stage 3: birth rates fall, and the growth rate falls. Stage 4: birth and death rates equilibrate & r = 0 again (not equal to 0 but near 0 again)
