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I. CHARACTERISTICS OF I. CHARACTERISTICS OF POPULATIONSPOPULATIONS
A. Density and Abundance– Abundance refers to the number of
individuals, N.
– Density refers to the number of individuals per unit area
I. CHARACTERISTICS OF I. CHARACTERISTICS OF POPULATIONSPOPULATIONS
A. Density and Abundance– Relation to body size
Mass (g)
100 101 102 103 104 105 106 107
De
ns
ity
(#
/sq
km
)
10-1
100
101
102
103
104
D = 16,982M-3/4
Source: Damuth (1981, Nature 290:699)
I. CHARACTERISTICS OF I. CHARACTERISTICS OF POPULATIONSPOPULATIONS
A. Density and Abundance
large species occur at lower densities
relationship exists with metabolic rate:
3/ 416,982D W
3 3 3 304 4 4 4 x RMR D W W W W
I. CHARACTERISTICS OF I. CHARACTERISTICS OF POPULATIONSPOPULATIONS
A. Density and Abundance
B. Vital Rates– Fertility rate
– Mortality rate
– Immigration rate
– Emigration rate
I. CHARACTERISTICS OF I. CHARACTERISTICS OF POPULATIONSPOPULATIONS
A. Density and Abundance
B. Vital Rates
C. Age Structure – proportion of individuals of various
ages
I. CHARACTERISTICS OF I. CHARACTERISTICS OF POPULATIONSPOPULATIONS
A. Density and Abundance
B. Vital Rates
C. Age Structure
D. Sex Ratio – ratio of males to females
– example 60:40
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
A. Growth in a Constant Environment with Unlimited Resources– population doubles monthly
– N after 4 months = ?
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
A. Growth in a Constant Environment with Unlimited Resources
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
Geometric model:
Time (month)
0 1 2 3 4
N
0
10
20
30
40
50
0
10
20
30
40
50
Nt = N0t
= 2 = finite rate of change
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
Exponential model:
Time (month)
0 1 2 3 4
N
0
10
20
30
40
50
0
10
20
30
40
50
Nt = N0ert
r = ln() = instantaneous rate of change
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
Growth rate is independent of N
Time (month)
0 1 2 3 4
N
1
10
100
1
10
100
Nt = N0t
= 2, r = ln(2) = 0.69
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
– Intrinsic rate of increase
Mass (g)
100 101 102 103 104 105 106 107
r m
10-2
10-1
100
101
rm = 18M-0.36
Source: Caughley and Sinclair(1994, Wildlife ecology and management)
Herbivorous Mammals
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
B. The Importance of Considering Environmental Variation– Red deer and spring temperature
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
B. The Importance of Considering Environmental Variation– Cotton rats on the northern fringe
II. DENSITY-INDEPENDENT II. DENSITY-INDEPENDENT POPULATION GROWTHPOPULATION GROWTH
B. Importance of Environmental VariationSpecies Spring Captures
Cotton rats 22%
Prairie voles 99%
White-footed mice 83%
Deer mice 80%
Harvest mice 66%
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