Darwin’s Natural Selection Worksheet
Name ___________________________________
Read the following situations below and identify points of Darwin’s natural selection.
1)
There are 2 types of worms: worms that eat at night (nocturnal) and
worms that eat during the day (diurnal). The birds eat during the day
and seem to be eating ONLY the diurnal worms. The nocturnal worms
are in their burrows during this time. Each spring when the worms
reproduce, they have about 500 babies but only 100 of these 500 ever
become old enough to reproduce.
Identify a type of variation in the worms. ______________________________________________________
Which variation is most favorable? _______________________________________________________
In 50 years, what will natural selection have most likely done for the worms?
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What adaptations might occur in the birds in 100 years? ______________________________________
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2) There are 3 types of polar bears: ones with thick coats, ones with thin
coats and ones with medium coats. It is fall, soon to be winter. The
temperatures are dropping rapidly and the bears must be kept warm,
or they will freeze to death. Many of the bears have had ~2 cubs each
but due to the extreme temperatures, many mothers only have one cub left.
Identify a type of variation in the polar bears ______________________________________________________
Which variation is most favorable? _______________________________________________________
In 50 years, what will natural selection have most likely done to the polar bears?
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3)
In ostriches, there are 2 types: ones that run fast and those that
run slowly. The fast birds can reach up to 40 miles an hour.
Jackals love to eat ostrich, and they can reach speeds of up to 35-40
miles per hour. A flock of ostrich will lay ~ 10 eggs (each mother only lays 1),
but many rodents break into the eggs and eat the fetus before they hatch.
Identify a type of variation in the ostriches ______________________________________________________
Which variation is most favorable? _______________________________________________________
In 50 years, what will natural selection have most likely done to the ostriches?
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What adaptation might occur in the jackals in 100 years? ____________________________________
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#4: A population of insects is sprayed with a new insecticide. Most of the
insects are killed but a few survive. In the next generation, many more of the
insects are unaffected by the insecticide. Which of the following BEST
explains these results?
a. The insecticide caused a mutation in the species.
b. A few insects in the first population were immune and passed
this trait to their offspring.
c. The insecticide caused a side effect of immunity that was
passed on to the next generation of insects.
d. The insects learned to fight off the insecticide.
5) There are two types of rabbits: those that strictly eat grass and those
that strictly eat berries and flowers. A drought occurs one year, and the
plants have difficulty producing any extras (flowers, berries, etc.).
They can only try and keep themselves green. The rabbits have
had babies all year long but many are eaten by foxes or hawks
Due to the drought, many have starved to death.
Identify a type of variation in the rabbits. ______________________________________________________
Which variation is most favorable? _______________________________________________________
In 50 years, what will natural selection have most likely done to the rabbits?
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6)
Describe how natural selection is occuring in the
image above. Be sure to use the word adapt and
variation:
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7)The table below describes four types of female mice that live in a beach area with mostly tan sand and
scattered plants. Which of the four mice types would be considered most favorable for natural selection?
Explain: _______________________________________________________________________________________
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Color of fur
Age at Death
# of mice produced by
Running speed
each female
Black
2 months
0
8 cm/sec
Tan
7 months
11
6 cm/sec
Tan-Black mix
8 months
3
7 cm/sec
Cream
2 months
0
5 cm/sec
Due to natural selection, what could you expect to occur to the mice on this beach over several years?
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8)Snowy owls are beautiful white owls that live in the arctic. They are able to withstand the frigid temps of
the arctic. They usually migrate south to southern Canada during the middle of the arctic winter, but soon
return far north. Explain how the population would respond in the following scenario:
a)The snowy owls environment is warming up very quickly and going from very frigid temperatures to
very warm. This change is happening so quickly that the snowy owls are too visible to their prey since
there is less snow. They have started having a hard time finding food and many are starving. The warmth
has also messed up their migration/breeding patterns. _____________________________________________
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