Population Ecology Campbell Chapter 47

Use the links to fill in some of the gaps in your understanding of population ecology. Click for Another overview

In chapter 21 the emphasis was on populations as interbreeding groups of individuals of a single species. In chapter 47 population is defined in ecological terms as individuals of aone species that occupy the same general area (habitat) at the same time. Mambers of a population rely on the same resources and are influenced by similar environmental factors

1. Two important characteristics of any population are density and spacing of individuals. (Population dynamics)

a) measuring density: estimation is more common than a direct count. Why? __________________


formula for mark-recapture estimate of population size: _________________________

Give examples of other techniques used to estimate population size. ________________________________

b) patterns of dispersion (distribution of populations) _______________ , _________________, _______________

2 . Demography is the study of factors that affect birth and death rates in a population. Simulation software is available on line.

a) Age structure and sex ratio
age structure (see age pyramids fig. 47.22 -- note labels on these diagrams) and predicting with population pyramids
List and describe organisms without overlapping generations _______________________

• define birth rate (fecundity) / death rate _____________________________________________ (diagram example)

When is death rate normally highest in a population _______________________________

generation time (see fig. 47.3 and complete the graph below)

b) Life tables and survivorship curves. Define:
• Life tables __________________________________________________________________

• cohort _____________________________________________________________________

• survivorship curves (Complete the diagram below)

3. The traits that affect an organism's schedule of reproduction and death make up its life history.

a) Variation in life histories (give examples)

b) Allocation of limited resources. The life history of an organism represents the resolution of several conflicting demands based on limited resources and competing life functions.

An organism's biological fitness (based on the reproductive success of offspring) can be evaluated in terms of three questions:

1. How often should an organism breed?

2. ______________________________________________

3. ______________________________________________

Define or give examples of:

• number of reproductive episodes per lifetime (describe advantages of each)
- one shot ____________________________________________________________

- multiple events _______________________________________________________

• age at first reproduction _______________________________________________________

clutch size __________________________________________________________________

4. A mathematical model for exponential growth describes an idealized population in an unlimited environment.

define changes in population size during a fixed time interval with this verbal equation


now use a symbol equation . _____________________________________________

What is r? ____________________

Explain zero population growth. _________________________________________________

Exponential growth model. Malthus

The maximum population growth rate is called _____________________________ and symbolized as _________

Population increase under these conditions is called _______________________________ and can be calculated using the equation below.


The size of a population that is growing exponentially increases rapidly resulting in a ________ shaped growth curve. The exact shape depends on r max .

Label the plots of generation time vs rmax in terms of body mass; and the graphs of exponential growth which differ by the value of r max.

5. A logistic model of population growth incorporates the concept of carring capacity (K). This model produces a sigmoid or ______________ growth curve as N is plotted over time. (N = population size)

• define carrying capacity, K __________________________________________________

a) The logistic growth equation: _____________________________________________________

Logistic population growth (examples) ___________________________________________________


The actual growth rate of a population at any population size is expressed as ________________

Give examples where the assumption of the Logistic model do not apply. ___________________



b) Population growth models and life histories. Tradeoffs
K-selected populations (equilibrium populations) ____________________________________

r-selected populations (opportunistic populations) ___________________________________

Current position regarding K and r- selected population models: _______________________

6. Both density-dependent and density-independent factors can affect population growth.

The exponential and logistic models predict very different patterns of population growth. This difference is: _____________________________________________________________________________

Density-dependent factors are based on reduction of resources and result in a decrease in growth rate (r).

Density-dependent factors result in intraspecific __________________ . These factors intensify as the population increases. They help set the value of _______ or carrying capacity

Increasing population density may be limited or regulated by:

a) decreased nutrient availability b) _________________________

c) ______________________ d) _________________________

e) ______________________ f) __________________________

Density-independent factors. (unrelated to population size)

• most common and important of these factors are __________________________________

• Often populations fluctuate in sync with seasonal changes. How do the Australian thrip populations change in response to density-dependent and density-independent factors.





Population cycles: Describe the classic lynx and hare population cycles. Pick one of the hypothesis and explain why the lynx population always spikes after the hare population.


7. Explain why "the human population has been growing exponentially for centuries but will not be able to do so indefinitely."




Population Clock (USA)

Four kinds of population patterns

Campbell Population Ecology

Lecture on Population Ecology