1. Chapter 14: Population Ecology
Population Dynamics
Chapter 14: Population Ecology

2. Read the blurb about zebra mussels p.g. 646.
As a group (and with your teacher’s help) work through the questions below.

3. Characteristics of Populations
Population size
Number of individuals of a species occupying a given area at a given time
Population density (D)
D=N N: Total number of individuals
S S: Space occupied by the population
Small organisms usually have higher population densities than larger organisms

4. Characteristics of Populations-cont’d
Crude density
Population density measured in terms of the number of organisms of the same species within a habitat’s total area
Ecological density
Population density measured in terms of the number of organisms of the same species within the area actually used by those organisms (ex. land animals do not live in lakes)

5. 1. ) Complete worksheet on calculating population density. 2
1.) Complete worksheet on calculating population density. 2.) Worksheet #1 in population ecology packet 3.) a.) Design your own question (with diagram) for pop. Density b.) Crude and ecological densities c.) share with classmates

6. Characteristics of Populations-cont’d
Population dispersion patterns (fig. 4, page 652)
Clumped dispersion (ex. schools of fish)
Uniform dispersion (ex. King penguins)
Rarely found in nature
Random dispersion (ex. rainforest trees)

7. 1st half of page 2 in population ecology handout.

9. Characteristics of Populations-cont’d
Often, impractical to count exact numbers of a population
Count a sample and then estimate total size
Sampling techniques:
Quadrat sampling
Mark-recapture method
Technological tracking devices

10. Characteristics of Populations-cont’d
Quadrat sampling
Used for stationary or small organisms (ex. plants, insects)
A quadrat (ex. 1m2) is used and a sample of populations is counted within that area.
Population size and density can be extrapolated for the entire area based on that quadrat’s data.

11. 1. ) Worksheet on Quadrant sampling 2
1.) Worksheet on Quadrant sampling 2.)“Too Many to Count” activity with a group 3.) Page 2 – 3 (quadrant sampling) in population ecology packet.

13. Characteristics of Populations-cont’d
Mark-Recapture Method
for mobile wildlife.
sample captured, marked and then released
Marked animals mix randomly with unmarked animals and then a second sample of animals is captured
Marked to unmarked animals can be used to estimate the size of the entire population.

14. Characteristics of Populations-cont’d
Mark-Recapture Method-cont’d
M = m
N n
M = Total # marked
N = Total population
m = # of recaptures
n = Size of 2nd sample
Ex.) on p.g. 655

16. Mark and recapture worksheet.

17. Characteristics of Populations-cont’d
Technological Tracking Devices
When capturing animals for estimating population size, researchers may also attach radio collars, satellite-linked devices or other technological equipment
Used to track migration and/or behaviour patterns
Information can be mapped in geographic information systems (GIS)
Must ensure these devices do not harm the animals or restrict their activities

18. Complete pages 3 & 4 in your Population ecology packet.

20. Measuring and Modeling Population Change
Carrying capacity
The maximum number of organisms that can be sustained by available resources over a given period of time

21. Measuring and Modeling Population Change
Population dynamics
Changes in population characteristics determined by natality, mortality, immigration and emigration
Fecundity
The potential for a species to produce offspring in one lifetime (ex. high fecundity-starfish; low fecundity-humans)

22. Measuring and Modeling Population Change
Biotic potential
The maximum rate a population can increase under ideal conditions
Population change =
[(births + immigration)-(deaths + emigration)] x 100
initial population size (n)

23. Measuring and Modeling Population Change
Open population
Size and density influenced by births, deaths, immigration and emigration
Closed population
Size and density Influenced by births and deaths only
No migration occurs

24. Measuring and Modeling Population Change
Three general survivorship patterns of species:
Type I: High survivorship until fairly late in life, then high mortality
Typically produce small numbers of offspring
Type II: A fairly constant death rate
Type III: Low survivorship early in life (ex. green sea turtles)
Typically produce large numbers of offspring

25. Complete page 5 in your Ecology Packet.
Try out the calculating populations worksheet using the formulae they provide for you.

27. Measuring and Modeling Population Change
Geometric growth
Population grows rapidly during breeding season then declines throughout the rest of the year until the next breeding season
Growth rate is a constant from year to year but not during the year

28. Measuring and Modeling Population Change
Geometric growth-cont’d

29. Read pages 662-664 and complete page 6 in population ecology packet.

30. Measuring and Modeling Population Change
Exponential Growth
Doubling time is a constant value
Populations exhibiting this growth increase in numbers rapidly
Results in a J-shaped growth curve
Although the overall graph appears similar to geometric growth (J-shape), in this case, there are no fluctuations (jumps) as a result of breeding times

31. Measuring and Modeling Population Change
Exponential growth-cont’d

32. Read P. g. 664-665 and complete the corresponding part on p. g
Read P.g and complete the corresponding part on p.g. 7 in Population ecology packet

33. Measuring and Modeling Population Change
Logistic Growth
Most common growth pattern seen in nature
Geometric and exponential models assume that a population will grow indefinitely at the same rate
Realistically, limiting factors limit population growth and the population reaches the ecosystem’s carrying capacity
At the carrying capacity, the number of births and the number of deaths become equal

34. Measuring and Modeling Population Change
Logistic Growth-cont’d

35. Measuring and Modeling Population Change
Logistic Growth
S-shaped (sigmoidal) curve
Three distinct phases:
Lag phase: Population is small and increasing slowly
Log phase: Population undergoes very rapid growth.
Stationary phase: Population growth slows / stops
Occurs at or close to the carrying capacity. Population is at dynamic equilibrium (births=deaths) and no net increase in numbers occurs.

36. Read pages 666- 669 and complete page 7 -8 in population ecology packet.