Quantitative changes in population Flashcards
What are the 3 growth modes?
- Linear
- Unrestricted exponential
- Logistic
What is the growth rate for Linear growth mode?
-dN/dt= c
What does the Linear growth mode describe?
-It describes that growth is constant & independent of population size
What is the growth rate for the Unrestricted Exponential growth mode?
-dN/dt= rN
What does the Unrestricted Exponential growth mode describe?
-It describes that the growth rate is proportional to population size
What is the growth rate for the Logistic growth mode?
-dN/dt= rN( K-N/ K)
What does the Logistic growth mode describe?
-It describes that the growth rate is influenced by the difference between carrying capacity & population size
What does the variable K stand for?
-The carrying capacity
What 2 things DO NOT affect the carrying capacity?
- The initial population
- and the intrinsic rate of increase= little r (found in genetics)
What is the variable r stand for?
-The intrinsic rate of increase (genetic)
What occurs in Linear growth?
- A fixed # of cells reproduce in each generation
- The slope (rate of increase) is constant
What occurs in the Unrestricted Exponential growth?
- A fixed proportion of the cells reproduce
- The growth rate is proportional to population size
What occurs in Logistic growth?
- At first there is a Lag phase= number of births is greater than the # of deaths but slow growth
- Then enters the Log phase= many organisms are reproducing= accelerating growth
- Finally enters the stationary phase= birth & death rates are equal
What is the population size equation for linear growth?
N=ct+ N0
What does the variable c stand for?
-Rate of increase (change in population size per unit time)
