# ZOL 355 Lecture Notes - Lecture 17: Logistic Function, Exponential Growth, Loggerhead Sea TurtlePremium

7 pages50 viewsSpring 2018

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**preview**shows pages 1-2. to view the full**7 pages of the document.**Lecture 17: Population Ecology, Logistic Growth

• Brief Review: Exponential & Geometric Growth Equations for Estimating

Population Size N and Growth Rate r or λ

• Assumptions of the exponential growth equation

o When is the exponential growth equation a reasonable model for

population growth?

o All populations have the potential for exponential growth but

o this is not the case for long, Why?

▪ There is a limit to the population; space, food, etc.

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• Population growth is limited by the carrying capacity or K such populations

experience logistic growth.

o Comparison of logistic and exponential growth curves

▪ Carrying Capacity - the maximum amount a population can be

▪ K is a population size that has reached its max size

o Comparison of equations for population growth rate for logistic and

exponential growth

▪ Exponential Growth Logistic

▪ (unrestricted) (restricted or bounded)

▪ dN/dt = rN dN/dt = rN(1 – N/K)

▪ K = carrying capacity

▪ What happens to N and dN/dt if N=K?

• Population is not growing - its zero

▪ What happens to N and dN/dt if N<K?

• Population is decreasing

▪ What happens to N and dN/dt if N>K?

• Population is increasing

o K is the carrying capacity but also the equilibrium population size

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