1. Population Ecology
Chapter 53

2. Population
Groups of individual of the same species that live in the same place
Characteristics of populations
1. Population range
Area where it occurs
2. Spacing patterns
Spacing of individuals
3. Size

3. Population range No population is in all habitats
No population is static
1. Changing environment (receding glaciers)
2. Expansion to new areas

4. Cattle egret
Current
1970
1966
1965
1960
1961
1958
1943
1937
1951
1956
Figure 52.7 Dispersal of the cattle egret in the Americas
1970

5. Population
Density
Dispersion
Pattern of spacing

6. Spacing 1. Randomly spaced 2. Uniformly spaced 3. Clumped spacing
Little interaction
2. Uniformly spaced
Competition for resources
3. Clumped spacing
Uneven distribution of resources
Social interactions (herd, flock, pride)

8. Demography Statistical study of populations
Grows: births outweigh deaths
Shrinks: deaths outweigh births
Sex ratios (females > males)
Generation time (birth to reproduce)
Reproduction
Survivorship curves

9. Age structure Cohort Group of individuals that are of the same age
Fecundity:
Birth rate
Mortality:
Death rate
Age structure
# of individuals in a given cohort

10. Number of survivors (log scale)
Survivorship curve
1,000 I
100 II
Number of survivors (log scale) 10
Figure 53.6 Idealized survivorship curves: Types I, II, and III
III 1 50
100
Percentage of maximum life span

11. Factors regulate populations
Cost of reproduction
Age at first birth
Semelparity:
Single birth event
Annuals/insects
Iteroparity:
Several births over several years

12. Factors regulate populations
Carrying capacity K:
Maximum population an environment can sustain
Density-dependent effects
Increase density decreased birth rates
Light, water, space, food, disease
Density-independent effects:
Fire, volcano, cold

13. Number of hares (thousands) Number of lynx (thousands)
Carrying capacity
Snowshoe hare
160
120 9
Figure Population cycles in the snowshoe hare and lynx
Lynx
Number of hares
(thousands)
Number of lynx
(thousands) 80 6 40 3
1850
1875
1900
1925
Year

14. Factors regulate populations
K-selection:
Density dependent selection
r-selection:
Density independent selection

15. Human growth

16. Population pyramids

17. Life expectancy (years) Infant mortality (deaths per 1,000 births)
Fig 60 80 50 60 40
Life expectancy (years)
Infant mortality (deaths per 1,000 births) 30 40 20 20
Figure Infant mortality and life expectancy at birth in industrialized and less industrialized countries (data as of 2005) 10
Indus-
trialized
countries
Less indus-
trialized
countries
Indus-
trialized
countries
Less indus-
trialized
countries

18. 13.4 9.8 5.8 Not analyzed Log (g carbon/year) Ecological footprint
Figure The amount of photosynthetic products that humans use around the world
5.8
Not analyzed

19. 2,000 = 1.0N 1,500 = 0.5N Population size (N) 1,000 500 5 10 15
Fig
2,000 dN =
1.0N dt
1,500 dN =
0.5N dt
Population size (N)
1,000
500 5 10 15
Number of generations

20. Fig
8,000
6,000
Elephant population
4,000
2,000
1900
1920
1940
1960
1980
Year

21. Table 53-3

22. Exponential growth 2,000 = 1.0N 1,500 K = 1,500 Population size (N)
Fig
Exponential
growth
2,000 dN =
1.0N dt
1,500
K = 1,500
Population size (N)
Logistic growth
1,000 dN
1,500 – N =
1.0N dt
1,500
500 5 10 15
Number of generations

23. Number of Paramecium/mL
Fig
1,000
180
150
800
120
Number of Paramecium/mL
600
Number of Daphnia/50 mL 90
400 60
200 30 5 10 15 20 40 60 80
100
120
140
160
Time (days)
Time (days)
(a) A Paramecium population in the lab
(b) A Daphnia population in the lab