Transcript BIO211 Homeostasis

Higher Biology
Monitoring Populations
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Monitoring Populations
By the end of this lesson you should be
able to:
 Give four reasons for monitoring populations.
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Introduction
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Wild plant and animal populations are
regularly monitored to detect any
changes in their population numbers.
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Managing species used for food and
raw materials
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Humans make use of many species for:
Food
Raw materials
Fuel
Medicines
Housing
Furniture
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Managing a Species
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In order for a population to survive,
the death rate must not exceed the
birth rate.
When hunting or farming, it is
important to ensure that there is
enough of the population left to
replenish their numbers.
The Maximum Sustainable Yield (MSY)
is the numbers of individuals that can
be removed from a population without
affecting its productivity in the
future.
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Managing a Species- example
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Fish stocks in the North Sea have
been depleted due to over-fishing.
Governments set fishing quotasstating how many fish can be
harvested per year.
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Controlling Pest Species
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A pest is a species that is harmful to
humans, animals or crops.
Examples- insects, rodents, fungi
Monitoring the population of pest
species, provides information needed
to keep them under control.
They are controlled by either
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Chemical means- pesticides
Biological means- introducing the pest’s
predator.
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Controlling Pest Species-example
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Controlling
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Aphid (greenfly) numbers
Locust numbers- by monitoring
weather patterns and locust
swarms- early warnings can be
issued to areas likely to be
affected.
Rats- numbers monitored to limit
the spread of disease.
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Monitoring levels of Pollution
Indicator Species- indicate pollution
levels in an environment, by their
presence or absence.
e.g. Freshwater Invertebrates
Lichens
Birds of Prey
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Protecting Endangered Species
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Population numbers need to be
monitored to reveal those in
danger of extinction.
e.g.
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Currently there are only about
1100 pandas living in the wild and
about 40 in captivity (Chinese
zoos)
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Protecting Endangered Species
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In the 1930-1940s there were
estimated to be 3 to 5 million
elephants in Africa.
In 2002 there was less than 500, 000.
Reason?
Poaching and
illegal ivory trade.
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Protecting Endangered Species
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In 2002 there was 600
mountain gorillas left in
the wild- with none in zoos.
It is highly possible that this
species will be extinct in
your lifetime.
Many wild plants are also in danger of
extinction.
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Practice Questions
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1.
2.
3.
Torrance
TYK page 302 Q1-3a
TYK page 306 Q1&2
AYK page 310 Q7
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Monitoring Populations
Can you do it?
 Give four reasons for monitoring populations.
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