Biogeochemical cycles in an environment 1

Movement of nutrients in organisms

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. 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. 40-18a, p.716

19. Fig. 40-18b, p.716

20. Fig. 40-18c, p.716

21. Fig. 40-18d, p.716

22. Fig. 40-31b, 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.
40-
19a,
p.717

24. SUCCESSION IS RAPID
Soil is present and so are some
seeds that withstood the calamity.
Fig.
40-
19b
,
p.7
17

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