16
POPULATION DYNAMICS
POPULATION DYNAMICS
• Habitat: Set
87
75
60
30
1800
99
Source: Cunningham/Saigo, Environmental Science, 1999.
POPULATION DYNAMICS
POPULATION DYNAMICS
How do populations changeover time?
• Number of births
• Number of deaths
b = no. b/1000/year
R.N.I. = b - d• Growth rate r• R.N.I.
e.g. pop. = 10,000b = 2,000/yr (or 200/1,000)d = 1,000/yr (or 100/1,000)
r = 0.2 - 0.1 = 0.1 or 10%
Doubling Time
• Amount of time it would take for a population to double in size assuming a constant r
• Td = 0.7 r
r = (0.1 - 0.05) + (0.001 - 0.01)r = 0.05 - 0.009 = 0.041Td = 0.7 = 17 years 0.041
• Immigration: individuals entering a population• Emigration: individuals leaving a population
e.g. b = 1,000d = 500i = 10e = 100
Geometric vs Linear Growth• Starting salary of $1 for first week that then doubles each week
• Paid $10 per week with an increase in salary of $10 per week.
$0
$10,000
$20,000
$30,000
$40,000
$50,000
1 2 3 4 5 6 7 8 9 10 111213 141516
Time (weeks)
Inco
me
($)
$0
$200
$400
$600
$800
$1,000
Constant amount added tothe population
Exponent is multiplied tothe population
Source: Cunningham/Saigo, Environmental Science, 1999.
Depends on no. of offspring,their average survival rate, andhow early and often reproductiontakes place.
Source: Cunningham/Saigo, Environmental Science, 1999.
Source: Cunningham/Saigo, Environmental Science, 1999.
Source: Cunningham/Saigo, Environmental Science, 1999.
Source: Cunningham/Saigo, Environmental Science, 1999.
Source: Cunningham/Saigo, Environmental Science, 1999.
