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NATURAL SELECTION
MODEL
BY
ABHISHEK JAGUESSAR
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A population showingvariation in colour.
Continuous or
discontinuous?
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There is lots of food so your population survives and
reproduces. Add 5.
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The bright yellow of some of your offspring attracts
predators. All but two of them get eaten.
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Theres lots of food and hiding places for the green and
blue, but the red ones cant hide and get eaten.
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Plenty of food and its spring so another 10 offspring
are born, they are a variety of colours.
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Plenty of food and its spring so another 10 offspring
are born, they are a variety of colours.
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Its winter and 5 of your population die
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Its mating time again, blue and green mate and produce
5 green and 2 blue offspring. A mutation also produces
2 red offspring
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Its mating time again, blue and green mate and produce
5 green and 2 blue offspring. A mutation also produces
2 red offspring
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There is lots of food, and all reproduce 2 offspring, but
the white are better at finding water and hiding from
predators so they produce 5 offspring
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There is lots of food, and all reproduce 2 offspring, but
the white are better at finding water and hiding from
predators so they produce 5 offspring
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The bright red colour attracts mosquitoes carrying a
deadly disease. They all die.
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The bright red colour attracts mosquitoes carrying a
deadly disease. They all die.
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It is a particularly hot summer, blue and green are poor
temperature regulators; white and yellow, which reflect
heat, are more likely to survive.
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It is a particularly hot summer, blue and
green are poor temperature regulators;
white and yellow, which reflect heat, are
more likely to survive.
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When food is plentiful again the remainder mate and
produce 5 offspring some white and some yellow.
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When food is plentiful again the remainder mate and
produce 5 offspring some white and some yellow.
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A scientist finds this population and reports that this
species occurs in two colours. He says they have
adapted to their habitat. What does he mean?
What is the population?
Has it changed?
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In outline, Darwin stated the following:
Many more individuals are born than can possibly survive.
Individuals within a population vary slightly from one
another.
There is a frequent recurring struggle for existence.
Some individuals will have a better chance of surviving
than others (they will be naturally selected).
Any selected variety will tend to propagate its form.
Q.What did the individuals in our population compete for in
the struggle to survive?
Q.Which individuals were naturally selected?
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Lamarck (a french biologist) proposed:
During a life, structures or characteristics may be used or not
used.
Extensive use would lead to increased size and/or efficiency.
Characteristics acquired during a lifetime could be inherited and
so passed on to any offspring.
Q.Does our population show any evidence to contradict or
support Lamark?
To test Lamarcks theory, Weismann cut off the tails of mice forsuccessive generations.
Q.What should have happened if Lamarcks ideas were to be
supported?
Q.What do you think did happen?