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NAMES:
Biology
RAT ISLAND ACTIVITY
Each group will be assigned an island.
Your job will be to design a rat which
has adapted to the conditions of that
particular island. Then each group
must submit a drawing of their rat
and an explanation of how each
adaptation helps their rat survive on
the island. Answer the questions as
well.
ISLAND A:
The island is fairly flat, with an
occasional hill. The ground consists of
soft dirt. Several species of shrubs grow
toward the center of the island. There is
no animal life on land, but the water is
full of friendly fish that swim around the
island. The island is also surrounded by a
coral reef which keeps predators out.
The shore is sandy with no algal growth.
Fresh water is available.
ISLAND B:
The island has a rocky shoreline.
Numerous tide pools dot the island along
the shore where the wave action is
somewhat sheltered by rock outcrops.
The tide pools host barnacles, chitons,
abalone, sea urchins and crabs. Algae
grows all around the island; however it is
quite sparse in the tide pools where the
various animals feed. The current is quite
strong along the rocky outcrops where
the algae grows best. Freshwater is
available.
SCIENTIFIC NAME: Rattus norvegicus
(common brown rat)
My rat lives on island _________
My rat’s name is _________________
(Scientific name)
Common name ____________________
ISLAND C:
The island is somewhat barren. A few
species of cactus thrive on the bare
rocks. A large cactus-eating tortoise
inhabits the island. A species of very
large bird nests on the island annually.
They build their nests in the rocks, and
protect their eggs from the sun by
standing over the nests with outspread
wings. The nests are always found on the
windy side of the island which is
somewhat cooled by offshore breezes.
ISLAND D:
The island is an inactive volcano.
Vegetation in the island changes with the
altitude moving up the volcano. Grasses
grow at the base. Further up the slope
the grasses give way to low shrubs. Half
way up, the island becomes quite lush.;
tropical plants and trees dominate the
landscape. At this altitude, the island
experiences frequent rain showers. There
are two species of birds that inhabit the
island. One raptor and the other is a small
finch. The raptor enjoys eating small
rats.
RAT ISLAND QUESTIONS
1. The rats that floated off the ship to Islands A, B. C, and D, came from a high
population of ancestral rats from Island Jackson, where the ship originated.
Island Jackson is made of volcanic rock. The center part of the island has rolling
grasslands and many shallow lakes. Hidden within the caves near the grasslands are
the ferocious cougars that prey on the island rats. Below is a picture of your rat's
ancestor.
2. Explain how evolution occurs in terms of natural selection.
3. Variation within a species allows different phenotypes to be selected. Explain
how this is important for evolution to occur.
4. Speciation involves the creation of a new species from a common ancestor. How
might your new rat be different from the rat you drew above?
5. What is an adaptation?
6. Recall that fitness is the ability of an organism to survive and pass along it’s
genes to the next generation. How do adaptations affect the fitness of an
organism?
7. List some factors that your rat has to deal with on their island. Include
possible food options, predators they have to avoid, and any other
environmental problems that they may have to adapt to.
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8-12. In the table below, list 5 specific adaptations that your rat must have in
order to be successful in survival and reproduction on your island. Then briefly
explain why this adaptation will be beneficial. Use information about the island to
support your decisions in the reasons column. The adaptations must be believable.
Your rat probably didn’t grow wings or gills, for example.
Adaptation:
1.
Reason:
2.
3.
4.
5.
13. Draw your new rat on a piece of white paper with these adaptations.
14. What type of selection puts pressure on a population to adapt to their
environment? What’s another name for this?
15. How does your rat compete for natural resources on the island?
16. According to Darwin, what size litter would be most beneficial for your rat in
order to ensure survival and why?
17. If your rats third toe on their front left foot gets stuck between 2 boulders
and torn off, will this trait be passed on to their offspring? Explain.
18. Describe Lamarck's theory of evolution (check handout)?
19. How would Lamarck explain the differences between your rat and the ancestral
rat from Island Jackson?
20. How would Darwin explain the differences between your rat and the ancestral
rat from Island Jackson?