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Darwin’s Natural Selection Worksheet
1)
Name ___________________________________
There are 2 types of banded worms native to Indonesia: worms that eat at night (nocturnal) and worms
that eat during the day (diurnal). Humans have brought chickens to the island, and 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.
a. What worm has natural selection selected AGAINST? ________________ FOR? ________________
Darwin's 5 points: Identify the 5 points in the scenario above.
Population has variations. _________________________________________________________________
Some variations are favorable. _____________________________________________________________
More offspring are produced than survive._________________________________________________
Those that survive have favorable traits. ____________________________________________________
How will the population change over time? _________________________________________________
What is causing the gene frequency in this population to change?__________________________________
2) Polar bears are under extreme pressure from global warming. The ice flows they typically use for hunting
seals as they come to the surface to breathe are melting away. Some bears are able to swim for long
distances to find food, but others are reluctant to leave the area where they were born. Many of the
bears have had ~2 cubs each but due to lack of food, many mothers only have one cub left.
a. What bear will natural selection select AGAINST? ___________________ FOR? ________________
Darwin's 5 points: Identify the 5 points in the scenario above.
Population has variations. _________________________________________________________________
Some variations are favorable. _____________________________________________________________
More offspring are produced than survive._________________________________________________
Those that survive have favorable traits. ____________________________________________________
How will the population change over time? _________________________________________________
What is causing the gene frequency in this population to change?__________________________________
4) There are two types of rabbits: those that strictly eat grass and those that eat berries and flowers when they can. 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.
a. What rabbit will natural selection select AGAINST? _________________ FOR? _________________
Darwin's 5 points: Identify the 5 points in the scenario above.
Population has variations. _________________________________________________________________
Some variations are favorable. _____________________________________________________________
More offspring are produced than survive._________________________________________________
Those that survive have favorable traits. ____________________________________________________
How will the population change over
time?_______________________________________________________
What is causing the gene frequency in this population to change?__________________________________
5) Bob believes that giraffes have long necks because they have stretched their necks to try and reach food that is
high in trees. Since the parent had stretched its neck, it passed the long neck on to its offspring.
Ryan believes
that giraffes have long necks because the ones with longer necks were able to reach the food, and those with short
necks could not and died. The long necked giraffes reproduced, and soon all of the giraffes had long necks.
a. Who thinks like Lamarck? __________________________________________________
b. Who thinks like Darwin? ___________________________________________________
c. Describe how natuaral selection has favored long necks by filling in the blanks.
Thousands of years ago, all giraffes had short necks, much like their living relative,
the okapi (pictured above). Trees on the savannah are rare and very tall to prevent
herbivores from eating their leaves. This is an______________________ for the tree
(or a feature that helps it to survive). There were minor differences in the lenghts of the necks of these ancestral
giraffes, and we call these differences _______________________. The giraffes with the longer necks had
access to the lowest leaves on the trees, so they had a survival advantage over the short neck giraffes. In the next
generation the frequency of the ____________________ that control longer necks was higher. Because longnecked giraffes survived better and reproduced more, they can be said to have higher_____________________
than the short-necked giraffes. Over time the neck lengths continued to increase because the tallest individuals
were able to access more food. Therefore we can say that ____________________ ____________________ has
favored long necks in giraffes!
In red ciclid fish, large males defend schools of females as they lay their eggs and then fertilize them. They will
activly chase off any other males they see. Some males are very tiny, almost the size of females, and can sneak
past the large males and fertilize some of the eggs.
There are obviously two strategies that can lead to high reproduction in this fish. What vocabulary word
describes this ability to reproduce________________________?
Being small is a characteristic that can increase the fitness of these male fish. Therefore we would call this
small body size an _________________________.