1. Population Ecology Chapter 53

2. turtles

3. 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

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

5. Cattle egret Current 1966 1970 1965 1960 1961 1958 1951 1943 1937 1956 1970

6. Population Density Dispersion Pattern of spacing

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

9. Dispersion (a) Clumped (b) Uniform (c) Random

10. 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

11. 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

12. Survivorship curve 1,000 100 10 1 050100 II III Percentage of maximum life span Number of survivors (log scale) I

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

15. 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

16. Carrying capacity Snowshoe hare Lynx Number of lynx (thousands) Number of hares (thousands) 160 120 80 40 0 1850187519001925 Year 9 6 3 0

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

18. Human growth

19. Density dependent factors Competition for resources Territoriality Intrinsic factors Disease Predation Toxic wastes 5 µm

20. Population pyramids

21. Fig. 53-26 Less indus- trialized countries Indus- trialized countries 60 50 40 30 20 10 0 0 20 40 80 Life expectancy (years) Infant mortality (deaths per 1,000 births) Less indus- trialized countries Indus- trialized countries 60

22. Ecological footprint Log (g carbon/year) 13.4 9.8 5.8 Not analyzed

23. Energy use (GJ): > 300 < 10150–300 50–150 10–50

24. Growth Population growth rate  N= change in population size  t = change in time B=birth rate D=death rate

25. Growth B=births during specified time D= deaths during specified time b= annual per capita birth rate m (mortality)= per capita death rate N is population size B  bN D  mN

26. Growth r = (per capita rate of increase) r  b – m NN tt  rN

27. Fig. 53-10 Number of generations 051015 0 500 1,000 1,500 2,000 1.0N = dN dt 0.5N = dN dt Population size (N)

28. Fig. 53-11 8,000 6,000 4,000 2,000 0 1920194019601980 Year Elephant population 1900

29. Table 53-3

30. Fig. 53-12 2,000 1,500 1,000 500 0 051015 Number of generations Population size (N) Exponential growth 1.0N = dN dt 1.0N = dN dt K = 1,500 Logistic growth 1,500 – N 1,500

31. Fig. 53-13 1,000 800 600 400 200 0 051015 Time (days) Number of Paramecium/mL Number of Daphnia/50 mL 0 30 60 90 180 150 120 020406080100120140160 Time (days) (b) A Daphnia population in the lab(a) A Paramecium population in the lab