Download Ecology: Populations

Ecology: Populations
Ch. 24.2
Food and Space
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Organisms living in the wild do not
always have enough food or living
space.
Competition occurs when two or more
organisms seek the same resource at
the same time.
Competition for food, living space, or
other resources can prevent population
growth.
Population Size
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Population counts can help identify
populations that could be in danger of
disappearing.
The size of a population that occupies a
specific area is called population density.
Trap-mark counts and sample counts are
methods used to estimate the population
size of animals in a particular region.
Limiting Factors
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The availability of food, water, living
space, mates, nesting sites, and other
resources is often limited.
A limiting factor is anything that restricts
the number of individuals in a population.
Limiting factors include living and
nonliving features of the ecosystem.
A limiting factor can affect more than one
population in a community.
Carrying Capacity
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Carrying capacity is the largest number
of individuals of one species that an
ecosystem can support over time.
If a population begins to exceed the
environment's carrying capacity, some
individuals will not have enough
resources.
Individuals could die or be forced to
move elsewhere.
Biotic Potential
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The highest rate of reproduction under
ideal conditions is a population’s biotic
potential.
The larger number of offspring that are
produced by parent organisms, the
higher the biotic potential of the species
will be.
Under ideal conditions (unlimited supply
of food, water, and living space) the
population will continue to grow.
Changes in Populations
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Birthrates and death rates influence the
size of a population and its rate of
growth.
Animals moving from one place to
another can affect population size in a
particular area.
Even plants and microscopic organisms
can move from place to place, carried by
wind, waster, and animals.
Exponential Growth
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Exponential growth means that the
larger a population becomes, the faster it
grows.
This can cause competition for food and
den sites that will lead to an equilibrium
in the population’s growth.
Population Practice Problem
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An ecologist wants to know the size of
wild tulip population growing in a
meadow. The meadow measures 1,000
m (squared). There are 50 tulips in an
area that is 100 m (squared). What is the
estimated population of tulips in the
whole meadow?
Solution
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1000 / 100 = 10
50 x 10 = 500 tulips
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Predator- the organism that is seeking
out another organism to eat, the hunter
Prey- the organism being hunted