BSCI 106 Lecture Notes - Lecture 3: Thomas Robert Malthus, Maximum Sustainable Yield, Logistic Function
11 Jul 2016
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Document Summary
Population growth (dn/dt) is a function of: rmax = births are high and deaths are low, n = number of individuals added to the population is related to the number of individuals reproducing. Exponential growth: dn/dt = rmax n, j-shaped curve. Logistic growth: dn/dt=rmax n * (k-n)/k, s-shaped growth curve. Most populations grow quickly at low densities, but growth rate slows down at high densities. Once the population (n) gets large enough, the population will stop growing altogether: r=0 r decreases as n increases. Maximum sustainable yield (msy: commonly used fisheries model, goal: harvest maximum number of individuals possible without reducing the population size over the long term, warnings. Harvesting large fish and replacing them with small will reduce r. Biological significance (why does r go down as n increases?) Density dependent factors: competition for food, space, and shelter, stress as n increases. Cost of rarity negative growth rates at low densities.
