Download A population and its sustainability

Kostanay Baitursynov State University
Course “Ecology and Sustainable Development”
Theme “A
population and its
sustainability”
G.Yunussova
Plan:
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1 The concept of population.
2 Population size, density of a population
3. Population structure
4 Degree of population isolation.
Population
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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
flock of pelicans
a school of dolphins
Population characteristics
Static
–
Density of population
Degree of isolation
butterfly population
Dynamic
Numbers (size)
Demographic structure
plant population
A population number
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or abundance or population size or
magnitude population
- a quantity or count of individuals of
a population on occupied territory
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Survivorship curves
N=B–D+E–I
Are we a population?
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What size have the population?
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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)
Population Limiting Factors
3. Population growth rate
– How fast a given population grows
– Factors that influence this are:
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•
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birth rate)
Natality (____
death rate)
Mortality (_____
Emigration (the number of individuals moving
away from a population)
_________
moving to
Immigration (the number of individuals _________
a population)
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.
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
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Predation
Disease
Parasites
Competition
Population Growth Rate
What population do you think this is?
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?
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)
Population Limiting Factors
•
Population growth models
– Logistic Growth Model
The S-curve is not as pretty as the image looks
1. Carrying capacity can be raised or lowered. How?
Example 1: Artificial fertilizers have raised k
Example 2: Decreased habitat can lower k
2. Populations don’t reach k as smoothly as in the
logistic graph.
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Boom-and-Bust Cycles
Predator-Prey Cycles
Example Problem
• There are 10,400 mice living in a 1000m x
1000m field. What is the density of this
population?
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.
The population structure
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Sex composition
Age composition
Spatial dispersion
Demographic pyramids
PATTERN OF DISPERSION
What types of spatial dispersion?
An isolation of populations
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a apartness of one population
from the adjacent similar one.
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Natural boundaries
Artificial (man-made) borders
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What kind of boundaries?
Control questions
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What population characteristics we learned
are static or dynamic?
What population characteristics static or
dynamic we consider as more important and
why?
Hometask
Study by self questions:
1 Types of Survivorship curves
2 K-selection and r-selection in a population
surviving
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