Bio_Lecture_9 - PopulationGrowth Populationgrowth...

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Population Growth Population growth Population: a group of individuals of the same species in the same  place Populations may display two types of growth: o Exponential o Logistic Exponential      Growth : all or a fixed proportion of individuals can  reproduce indefinitely Exponential growth Consider a case where we start with a single cell, and all cells can  reproduce Exponential growth curve Clearly not linear, an exponential function N time
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Exponential growth formula Growth Rate = change in size divided by change in time (dN/dT) Growth rate is slope of curve o dN/dT = rN o N = population size o r = the growth constant, or… o r = the increase in size per generation o r is calculated as the difference in the birth rate and the death  rate Exponential growth: by the numbers Consider what is happening numerically T 0 1 2 3 4 5 N 1 2 4 8 16 32 dN/dT 1 2 4 8 16 dN/dt increases with increasing N dN/dt is proportional to N (dN/dt = rN) Implications Even with lower r, dN/dt can be actually larger because of the higher  N o Ex: r = 0.4, N = 1000 vs r = 0.3, N = 1500
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Bio_Lecture_9 - PopulationGrowth Populationgrowth...

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