#9 - Population Growth

#9 - Population Growth - Some fundamental equations...

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1 Population sizes and growth rates Populations are collections of individuals! Individual birth rates and death rates, and the effect of competition/crowding on these rates, are acted on by natural selection and they evolve. Populations simply “follow along”. Remember life tables! Some fundamental equations • N 1 = N 0 R • N t+1 = N t R • N t = N 0 R t • N t /N t+1 = 1/R t N t / N t+1 100/200 = 0.50 100/150 = 0.67 100/100 = 1.00 100/75 = 1.33 a = (R-1) K
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2 Competition • Competition -- is an interaction between individuals, brought about by a shared requirement for one or more resources, that leads to a reduction in survival, growth and/or reproduction of at least some of the competing individuals. • Usually, competition increases as density increases, though the relationship may not be linear! (In fact, it is almost never linear.) How population growth is changed by competition (density) N t+1 = N t R “a” in the slide #4 All the term in the white box does is to slow down the rate of
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#9 - Population Growth - Some fundamental equations...

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