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Slide 1

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Chapter 13: Populations and
Sustainability…read more

Slide 2

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Limiting factor - Anything that stops a
population increasing in size
· Carrying capacity ­ The maximum
population size that can be sustained in
one area.…read more

Slide 3

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Predator-Prey Relationships
· Size of predator and prey populations are affected by each other
· 1. Lots of prey; predator population increases
· 2. Prey population decreases, as they are eaten Only occurs when
· 3. Predator population decreases, due to lack of food predator is main
· 4. Prey population increases due to less predation limiting factor of
· 5. Cycle repeats prey population
Only if prey only
has one predator,
and the predator
only has one prey…read more

Slide 4

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· Competition will always occur if something 2 organisms need is in short supply
· Intraspecific competition ­ between members of the same species. Involved in
natural selection
· Interspecific competition ­ between members of different species. Only occurs
when the niches of 2 species overlaps.
· Niche ­ The role an organism places in an ecosystem
Example one:
· 2 species of flour beetle
· When added to flour, the population of one always rose and then oscillated,
whereas the other slowly died out
· Very small change in conditions changes which survives
· Above 29 degrees ­ the other flour beetle survived.…read more

Slide 5

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Example 2:
· 2 beetles which live on stored wheat grain can coexist
· Larvae of one beetle eat from the inside of the wheat grain, whereas the
larvae from the other beetle eat from the outside of the grain
· Small difference in their niches allows them to co-exist.
Example 3:
· 2 species of barnacles; Chthamalus and Balanus
· Chthamalus can live further up shore ­ better at coping with less water
coverage and larger temperature fluctuations
· Balanus cannot live any further down due to predatory dog whelk
· More algae further down to compete for space
· Small area where both barnacles coexist
· Balanus grows faster, so wins a competition for space.
· Interacting factors ­ several different factors affect population size and
distribution.…read more

Slide 6

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· Conservation ­ the active management of ecosystems to maintain or
increase biodiversity.
· Preservation ­ keeping things as they are
Positive effect of resources eg.
walk in woodland wood
Social Economic Income from
People's jobs Reasons for tourism
rely on it eg. conservation
Plants used for
Ethical medicinal drugs
Our responsibility to We have no right to
look after the planet make other species
we live on Should learn extinct
to coexist…read more

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