BIO220H1 Lecture Notes - Lecture 7: Demographic Transition, Exponential Growth, Population Connection
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BIO220H1 Full Course Notes
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Bio120 treated fundamental ecological processes in natural systems. To date in 220 its been a mixture. Transition from just another species to a unique force: numbers and technology. This topic necessarily goes beyond previous material in: Human impact = function of population and consumption (affluence and technology) Per person, human actually make less polution if in urban area. If rates are constant and if (birth + immigration) > (death + emigration), growth trajectory is densityindependent and exponential. Model as dn/dt = rn; solved as nt = n0ert. Exponential growth cannot continue unchecked, so more complex models are needed. Simplest model of density-dependent regulation is the logistic: In mid-20th century, logistic model was viewed almost as an ecological law . Is n is small, we have exponential growth. As n (cid:314) k, population groeth levels off. Population growth rate is a function of density. Historical perspective from first really successful ecology textbook:
