1. Theme “A population and its sustainability”
Kostanay Baitursynov State University Course “Ecology and Sustainable Development”
Theme “A population and its sustainability”
G.Yunussova

2. Plan: 1 The concept of population.
2 Population size, density of a population
3. Population structure
4 Degree of population isolation.

3. Population
A group of living organisms of same species, constantly living on the same territory, freely interbreed.
an interbreeding group of individuals of a single species that occupy the same general area.
A flock of butterflies
herd of hippos
a school of dolphins
flock of pelicans

4. Population characteristics
Static – Dynamic
Density of population Numbers (size)
Degree of isolation Demographic structure
butterfly population
plant population

5. A population number
or abundance or population size or magnitude population
- a quantity or count of individuals of a population on occupied territory
N = B – D + E – I
Survivorship curves

6. Are we a population?
What size have the population?

7. Population dynamics 1 J-shaped exponential growth curve
2 S-shaped logistic grouth curve 
carring capacity K - the maximum number of a population an environment can support  over a long time
3 Periodic curve (prey – predator)

8. Population Limiting Factors
Population growth rate
How fast a given population grows
Factors that influence this are:
Natality (____ rate)
Mortality (_____ rate)
Emigration (the number of individuals moving _________ a population)
Immigration (the number of individuals _________ a population)
birth
death
away from
moving to 8

9. Population Limiting Factors
Density-independent factors
Factors that limit population size, regardless of population density.
These are usually abiotic factors
They include natural phenomena, such as weather events
Drought, flooding, extreme heat or cold, tornadoes, hurricanes, fires, etc. 9

10. Population Limiting Factors
Density-dependent factors
Any factor in the environment that depends on the number of members in a population per unit area
Usually biotic factors
These include
Predation
Disease
Parasites
Competition 10

11. What population do you think this is?
Population Growth Rate
What population do you think this is?

12. So, what do you think is going to happen to the human population?
We will probably reach our carrying capacity.
Our growth rate will start to look like most organisms, which is the Logistic Growth Model
Carrying Capacity (k)
What letter does this curve kind of look like?

13. Population Limiting Factors
Population growth models
Logistic Growth Model
Often called the S-shaped growth curve
Occurs when a population’s growth slows or stops following exponential growth.
Growth stops at the population’s carrying capacity
Populations stop increasing when:
Birth rate is less than death rate (Birth rate < Death rate)
Emigration exceeds Immigration (Emigration > Immigration) 13

14. Population Limiting Factors
Population growth models
Logistic Growth Model
The S-curve is not as pretty as the image looks
Carrying capacity can be raised or lowered. How?
Example 1: Artificial fertilizers have raised k
Example 2: Decreased habitat can lower k
Populations don’t reach k as smoothly as in the logistic graph.
Boom-and-Bust Cycles
Predator-Prey Cycles 14

15. Population Limiting Factors
Reproductive Strategies
Population Limiting Factors
Species that follow this pattern usually
Have a Boom-and-Bust Life Cycle
Have short life spans
Produce many offspring
Smaller organisms
i.e., fruit flies, mice, locusts
Don’t maintain a population near carrying capacity
Controlled by density-independent factors
They are called r-strategists (for rate of increase)

16. Population Limiting Factors
Population Ecology: Reproductive Strategies
Population Limiting Factors
Species that follow this pattern usually
Have long life spans
Produce few offspring that have a better chance of living to a reproductive age
Are larger organisms
i.e., elephants
Maintain a population at or near k
Controlled by density-dependent factors
They are called k-strategists (for karrying kapacity)

17. Example Problem
There are 10,400 mice living in a 1000m x 1000m field. What is the density of this population?

18. Answer The area of the field is 1,000,000 square meters (m2).
The density of mice is therefore 10,400 mice/1,000,000m2=.0104/m2.

19. The population structure
Sex composition
Age composition
Spatial dispersion
Demographic pyramids

20. PATTERN OF DISPERSION 

21. What types of spatial dispersion?

22. An isolation of populations
a apartness of one population from the adjacent similar one.
Natural boundaries
Artificial (man-made) borders

23. What kind of boundaries?

24. Control questions
What population characteristics we learned are static or dynamic?
What population characteristics static or dynamic we consider as more important and why?

25. Hometask Study by self questions: 1 Types of Survivorship curves
2 K-selection and r-selection in a population surviving