BIOLOGY 3SS3 Lecture 3: nonlinear.complete
26 Sep 2016
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Introduction: in linear population models, per capita rates are independent of popu- lation size, now we"ll discuss why large and small populations might have di erent birth or death rates. And what this implies about population dynamics. The rst law of population dynamics: if individuals are behaving independently: The population-level rate of growth (or decline) is proportional to the population size. The second law of population dynamics: exponential growth (or decline) cannot continue forever, something is changing the average rate at which populations we observe grow. Answer: as populations go up, pressure from natural ene- mies could go up even faster. Answer: not enough to go around: e. g. , oak trees use all the available light. Answer: resources are destroyed: e. g. , gypsy moths kill all the oak trees. Population regulation: all the populations we see are regulated. On average, population growth is higher when the population is lower. Lots of populations don"t look like they are regulated.
