BIO 2129 Lecture Notes - Lecture 9: Exponential Growth, Density Dependence, Genetic Drift
18 Oct 2016
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Population density often fluctuates around reasonably stable values. Fluctuating around a mean value because of natural factors. Chickadee --> under line, grows, over line, shrinks. Dense populations --> exceed k, shrinks, and vice versa. Relationship between population density and size of egg clutch. High density --> low number of eggs, low density-- > high clutch number. High population density at the beginning of the year --> higher mortality. Population growth rates are proportional to population density r = b - d = f(population density) Interactions more likely --> disease spread more and faster, transmission. Secondary to there being a limitation to resources. Or just don"t get along and kill each other eg. lions killing cheetahs, mostly cubs etc. As population density increases, death rates increase and/or birth rates decrease. Population density tends to approach a stable value. Tigers in indonesia, just can"t find each other. Humans in exponential growth, where the exponent keeps increasing too, hyper exponential growth.
