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Ecology. Organisms. Organisms. Niche. It is an organisms role in the community. It includes: what it eats What eats it What and how much resources it uses Can you think of an example?. Limits on population size. - PowerPoint PPT Presentation
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Ecology
Organisms Organisms
Niche• It is an organisms role in the community.
It includes: – what it eats– What eats it– What and how much resources it uses
• Can you think of an example?
Limits on population size• The maximum number of individuals of a
species that an area can support is called carrying capacity
• Limiting factors are factors that limit a populations size– Factors can be abiotic or biotic
Population growth
dNdt
1.0N Exponential growth
Logistic growth
dNdt
1.0N1,500 N
1,500
K 1,500
0 5 10 150
500
1,000
1,500
2,000
Number of generations
Pop
ulat
ion
size
(N
)
Limiting factors• Examples of abiotic include:
– Oxygen in a pond,– amount of sunlight – Temperature
• Examples of biotic factors include:– Predators– Competition
Figure 53.10 Examples of terrestrial and marine food chains
Figure 53.11 An antarctic marine food web
Other feeding relationships
• Decomposers break down dead plants and animals.– This recycles the materials
• Scavengers are consumers that eat dead organisms
• Parasites attack living organisms
Figure 54.2 Fungi decomposing a log
Figure 54.11 An idealized pyramid of net production
• Materials are recycled but energy is NOT
• Ecosystems need a constant source of energy from the sun.
Figure 54.17 The carbon cycle
Biodiversity• Is the measure of how many different
species there are in an area• Ecosystems that have a high biodiversity
are more stable• It is valuable to humans because it can be
a source of medicine.• What other benefits are there?• Name a human activity that can lead to the
loss of biodiversity
Loss of Biodiversity• Direct Harvesting
• Habitat destruction– Deforestation
• Imported Species
Water Pollution
• Sewage and animal wastes add nutrients to the water
• This causes algae to grow more and die more
• Decomposers suck oxygen out of the water
• If too much oxygen is removed, the fish begin to die
Toxic Wastes• Chemicals that are added to lakes and
rivers can kill off many kinds of organisms
• An example is DDT
• Biological control
Burning fossil fuels• Burning oil and coal releases CO2 and sulfur into
the air• Sulfur in the air will lead to acid rain that can
damage or kill plants and animals– Can cause some lakes to be so acidic that nothing can
live there
• CO2 is a greenhouse gas and can lead to global warming– Ice caps can melt causing a rise in sea level and loss
of coastline
Ozone Depletion• Ozone is found in the upper atmosphere• It absorbs much of the harmful radiation
from the sun• Depletion of the ozone will allow more
harmful radiation to hit the Earth• This can lead to higher mutation and
cancer rates.