1. Understanding Populations
Chapter pg 210
Understanding Populations

2. What is a population?
“all the members of a species living in the same place at the same time”

3. Properties of Populations
Density -
“the number of individuals per unit area or volume”
Ex - # bass fish per cubic meter of water
Dispersion –
“ the relative distribution or arrangement of it’s individuals in a given amount of space”
Even
Clumped
Random

4. Growth Rate Change in pop. size = Births – Deaths
If adults in a population are not replace by new births, the growth rte will be negative and the population will shrink

5. How Fast can the Population Grow?
Biotic Potential =
Fastest rate at which its population can grow.
Limited by:
The organism’s:
Repro. Potential

6. Reproductive Potential
1. Number of offspring produced at one time
2. How often does the organism reproduce
3. how soon can the organism reproduce (age!?)

7. Logistic Growth
Population grows initially and then begins to taper off and only carry the amount suitable
for the ecosystem
Shows a S shaped
curve

8. Exponential Growth Population growth that grows faster and faster!
Produces a J-Shaped curve

9. Limits to population Growth
1. Carrying Capacity
2. Resource Limits
3. Competition within a population

10. 1. Carrying Capacity
Defined as the maximum population (number) that the ecosystem can support.
Will crash when it reaches capacity due to disease, etc.

11. 2. Resource Limits
A particular resource that is consumed by a particular species (food, water, etc) is called a “LIMITING FACTOR”
CC is reached when the species is consuming it at the same rate it is being produced.

12. 3. Competition Within a Population
= Members of a population use the same resources in the same way so they will eventually compete with one another as the population approaches it carrying capacity.
Ex = Christmas time
and Limited toys

13. 2 types of Competition: Direct = direct fighting for resources
Ex – food
Ex – Limited # of Elmo dolls at target at an
8 am sale and
400 mommies
waiting outside!
Indirect
= indirect fighting for resources
Ex- nocturnal vs. diurnal
Ex – mommy arrives at a 24 hour Target and buys the last doll before another mommy arrives at 8 am!

14. Two types of population Regulation:
=The cause of death to regulate the population size can be:
Density Dependant
Density Independent

15. Density Dependant
= Death occurs more quickly in a crowded population than a sparse one.

16. Density Independent
= death that is caused regardless of the pop.’s density.
It affects all members of a population in a general/similar way.

17. 8.2 How species interact with each other (pg. 217)
Niche
= role in the ecosystem.
Ex – decomposers niche is to recycle nutrients in its ecosystem!
Habitat
= location.
Ex -Where an organism lives

18. Species Interactions page 218
= based on whether each species causes benefit or harm to the other species in a given relationship.
Competition
Predation
Parasitism
Mutualism
Commensalism

19. Competition Defined as both species being harmed.
May be in competition for mates, territory, food, etc.

20. Predation
= defined as: benefits one and harming
the other

21. Symbiosis: Symbiosis is the relationship in which 2 species interact.
Typically in which one benefits.
1. mutualism
2. parasitism
3. commensalism

22. Mutualism
= defined as:
Benefits both!

23. Parasitism
= defined as: benefits one, harms the other

24. Commensalism
= defined as one benefits and the
other is unaffected.