1. Population Ecology

2. What is a population?
A group of individuals of the same species occupying a given area
Can be described by demographics
Vital statistics such as size, density, distribution, and age structure

3. Some characteristics of populations
Density and Distribution
Number of individuals in some specified area of habitat
Crude density information is more useful if combined with distribution data

4. Determining Population Size
Direct counts are most accurate but seldom feasible
Can sample an area, then extrapolate
Capture-recapture method is used for mobile species

5. Assumptions in Capture-Recapture
Marking has no effect on mortality
Marking has no effect on likelihood to being captured
There is no immigration or emigration between sampling times

6. Growth Rates of Populations Exponential growth
Population size expands by ever increasing increments during successive intervals
The larger the population gets, the more individuals there are to reproduce
J curve

7. Growth Rates of Populations Logistic Growth
As size of the population increases, rate of reproduction decreases
When the population reaches carrying capacity, population growth ceases S curve
Maximum number of individuals that can be sustained in a particular habitat

8. Growth Rates of Populations Overshooting Capacity
Population may temporarily increase above carrying capacity
Overshoot is usually followed by a crash; dramatic increase in deaths
Boom and Bust Curve

9. Which of the following is a curve showing the growth rate of the human population?
A. S curve B. J curve C. Boom and Bust Curve D. None of the above, humans are unique.

10. Factors that effect Population growth
Limiting Factors
Any resource that is in short supply
Which determines the
Carrying capacity of that population
Maximum number of individuals that can be sustained in a particular habitat
Can be
Density dependent – factors that are effected by the population density
Density independent – factors that are NOT affected by the populations

11. Density-Dependent Controls
Logistic growth equation deals with density-dependent controls
Limiting factors become more intense as population size increases
Disease, competition, parasites, toxic effects of waste products

12. Density-Independent Controls
Factors unaffected by population density
Natural disasters or climate changes affect large and small populations alike

13. Which of the following is a density INdependent factor that will affect the population of deer in NJ?
A. Tsunami
B. Tick infections
C. Cold winters
D. Number of males in the population
E. None of the above

14. How do different species interact with each other?
SYMBIOSIS
Parasitism
Commensalism
Mutualism

15. Change in the composition of species over time
Succession
Change in the composition of species over time

16. Pioneer Species Species that colonize barren habitats
Lichens, small plants with brief life cycles
Improve conditions for other species who then replace them

17. Types of Succession Primary succession - new environments
Secondary succession - communities were destroyed or displaced

18. Primary Succession in Alaska’s Glacier Bay region
Begins where nothing
ever grew before
Primary species are
those that can withstand
conditions like extreme
heat, light, nutrient poor
Soil
Ex. Lichens, moss
Fig a, p.716

19. Fig b, p.716

20. Fig c, p.716

21. Fig d, p.716

22. Fig b, p.727

23. Secondary Succession
Anything that decimates the landscape and succession must begin again. Ex. Volcanic erruptions, fire, floods, Clear cutting and human interference.
Fig a, p.717

24. Succession is rapid
Soil is present and so are some seeds that withstood the calamity.
Fig b, p.717

25. Climax Community
Stable array of species that persists relatively unchanged over time
Succession does not always move predictably toward a specific climax community; other stable communities may persist