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Name: _____________________________ Period: _____ Date: _________________________
Population Genetics with Humans
and triangulites
Part 1: Kinds of Natural Selection
Most populations show a range of phenotypes similar to this
graph to the right. Just as our bar graphs from the
Human Adaptations lab did before the “story”.
What if the story was an example of… add the story
Directional selection?
1. Explain what directional selection is.
2. Show directional selection on the graph to the right.
Delete this space
3. Explain what would happen within the population.
4. What in the story could cause this happen?
Stabilizing selection?
5. Explain what stabilizing selection is.
6. Show stabilizing selection on the graph to the right.
7. Explain what would happen within the population.
8. What in the story could cause this happen?
Disruptive selection?
9. Explain what disruptive selection is.
10. Show disruptive selection on the graph to the right.
11. Explain what would happen within the population.
12. What in the story could cause this happen?
Here is an image of the variations in a population of mice:
Which of the above types of selection caused the following in the same population?
Explain how you know.
13. – 14.
15. – 16.
17. – 18.
Part 2: Genetic Drift
All of the above examples really have to do with evolution when it happens naturally.
19. Explain what genetic drift is. Include some things that can cause it.
Here are two ways this can happen. Explain each:
20. Bottleneck Effect
21. Founder’s Effect
22. – 23. Which kind of genetic drift is shown in
the picture to the right? Explain your
answer.
24. – 25. Which of the above two examples is shown in the picture above? Explain
your answer.
26. – 27. Which kind of genetic drift is
shown in the picture to the right?
Explain your answer.
Part 3: Speciation
There are 4 ways by which one species becomes another different one
(speciation). Each is listed below.
Reproductive Isolation
28. Explain what Reproductive Isolation is.
29. What in the story could cause this happen?
Temporal Isolation
30. Explain what Temporal Isolation is.
31. What in the story could cause this happen?
Behavioral Isolation
32. Explain what Behavioral Isolation is.
Fix answer key
33. What in the story could cause this happen?
Geographic Isolation
34. Explain what Geographic Isolation is.
35. What in the story could cause this happen?
36. – 37. The picture to the right shows the
evolution of a salamander into 2
species. Which of the above types of
isolation most likely caused it? Explain
how you know.
38. – 39. The picture to the right
shows how 2 different fish evolved when
the isthmus of Panama closed 3.5
million years ago. Which of the above
types of isolation most likely caused it?
Explain how you know.
40. – 41. The graph to the right
shows mating times for 3
different types of frogs.
Which of the above types of
isolation most likely caused
it? Explain how you
know.
42. – 43. The cartoon to the right is a cartoon from the
80’s. Which of the above types of isolation most
likely caused it? Explain how you know.
44. – 45. The picture below shows how 2 different fruit flies evolved when fed two
different foods. Which of the above types of isolation most likely caused it?
Explain how
you know.
Part 4: Kinds of Evolution
46. What is divergent evolution?
47. What kind of anatomy (structures) does it lead to?
48. What is convergent evolution?
49. What kind of anatomy (structures) does it lead to?
50. What is coevolution?
51. Give an example of coevolution.
52. What is adaptive radiation?
53. Give an example of adaptive radiation.
Identify each of following as divergent evolution, convergent evolution, adaptive
radiation or coevolution.
54.
55.
57.
58.
59.
(Darwin’s finches and beak shapes)
60.
(insect on a leaf)
61.
Answer Key_
Name: _
Period: _____ Date: _________________________
Population Genetics with Humans
and triangulites
Part 1: Kinds of Natural Selection
Most populations show a range of phenotypes similar to this
graph to the right. Just as our bar graphs from the
Human Adaptations lab did before the “story”.
What if the story was an example of…
Directional selection?
1. Explain what directional selection is.
When the population tends
towards one end of the spectrum
2. Show directional selection on the graph to the right.
3. Explain what would happen within the population.
Tend towards all large hands or all small
hands (all tall or all sort)
4. What in the story could cause this happen?
The bush with fruit got very, very tall, or
the spikes got tighter around the opening
Stabilizing selection?
5. Explain what stabilizing selection is.
When the population tends
towards on the middle of the
spectrum
6. Show stabilizing selection on the graph to the right.
7. Explain what would happen within the population.
Tend towards medium height and medium
sized hands
8. What in the story could cause this happen?
Tall or short more easily caught by a
predator, small/large hands too small to
grab/too big to fit through spikes
Disruptive selection?
9. Explain what disruptive selection is.
When the population tends
towards both ends of the spectrum
10. Show disruptive selection on the graph to the right.
11. Explain what would happen within the population.
Tends towards tall and short
only; small or large hands only.
12. What in the story could cause this happen?
Tall can defend itself, short can hide from
predators, small hands can get food, large
hands can beat up the little guys and steal
their food (?) 
Here is an image of the variations in a population of mice:
Which of the above types of selection caused the following in the same population?
Explain how you know.
13. – 14.
Disruptive Selection…tends towards opposites
(light and dark)
15. – 16.
Stabilizing Selection…tends towards medium
17. – 18.
Directional Selection…tends towards darker
colors
Part 2: Genetic Drift
All of the above examples really have to do with evolution when it happens naturally.
19. Explain what genetic drift is. Include some things that can cause it.
When changes happen in a population by
accident, rather than natural selection. Small
populations are especially susceptible to
genetic drift.
Here are two ways this can happen. Explain each:
some natural event occurs that
limits the phenotypes in the population (e.g.
flood)
20. Bottleneck Effect:
a small group leaves the
population and starts its own
21. Founder’s Effect:
22. – 23. Which kind of genetic drift is shown in
the picture to the right? Explain your
answer.
Founder effect…a small
population of butterflies
flew to a new island
24. – 25. Which of the above two examples is shown in the picture above? Explain
your answer.
Bottleneck effect…dark seals were selectively
hunted
26. – 27. Which kind of genetic drift is
shown in the picture to the right?
Explain your answer.
Bottleneck effect…the
smooshed bugs just
happen to be all dark
ones.
Part 3: Speciation
There are 4 ways by which one species becomes another different one (speciation).
Each is listed below.
Reproductive Isolation
28. Explain what Reproductive Isolation is.
When one species can no longer reproduce with
another. This is kind of a catch-all term for the
next 3.
29. What in the story could cause this happen?
The big hand ones adapt to eat another fruit
Temporal Isolation
30. Explain what Temporal Isolation is.
When one species no longer mates at the same
time as another, e.g. flowers at different times
of day, animals at different times of year.
31. What in the story could cause this happen?
Small handed people eat in the morning at
mate in the evening. Large handed people do
the opposite.
Geographic Isolation
32. Explain what Geographic Isolation is.
Some geographic barrier comes between
populations (river, mountain)
33. What in the story could cause this happen?
Tall people walk over the mountains to the
other side of the island. Short people don’t
Behavioral Isolation
34. Explain what Behavioral Isolation is.
Some kind of mating ritual changes (bird songs)
and no longer attract mates.
35. What in the story could cause this happen?
Big handed people like country music and no
one wants to mate with that!
36. – 37. The picture to the right shows the
evolution of a salamander into 2
species. Which of the above types of
isolation most likely caused it? Explain
how you know.
Geographic isolation...
they walked down
different sides of the
valley
38. – 39. The picture to the right
shows how 2 different fish evolved when
the isthmus of Panama closed 3.5
million years ago. Which of the above
types of isolation most likely caused it?
Explain how you know.
Geographic isolation...
they were in the same
water, but then the land
formed separating them
40. – 41. The graph to the right
shows mating times for 3
different types of frogs.
Which of the above types of
isolation most likely caused
it? Explain how you
know.
Temporal
isolation... Rana
spp. (frogs) mate
at different times
of the year.
42. – 43. The cartoon to the right is a cartoon from the
80’s. Which of the above types of isolation most
likely caused it? Explain how you know.
Behavioral isolation... the
mating songs are different
44. – 45. The picture below shows how 2 different fruit flies evolved when fed two
different foods. Which of the above types of isolation most likely caused it?
Explain how
you know.
Behavioral isolation...they eat different kind so
food now.
Part 4: Kinds of Evolution
46. What is divergent evolution?
When one organism evolves to become many,
they evolve to become different
47. What kind of anatomy (structures) does it lead to?
Homologous structures
48. What is convergent evolution?
When two or more organisms evolve similar
traits but in different ways
49. What kind of anatomy (structures) does it lead to?
Analogous structures
50. What is coevolution?
When two or more organisms evolve together
(one changes and the other changes, too)
51. Give an example of coevolution.
As flowers change the time they bloom, insects
that use them for food need to lay eggs
earlier/later
52. What is adaptive radiation?
When an organism evolves (divergent) into
many different organisms performing many
different tasks
53. Give an example of adaptive radiation.
Barnacles that live above the tide, at the tide
zone, under water, on rocks, on sand…
Identify each of following as divergent evolution, convergent evolution, adaptive
radiation or coevolution.
54.
Divergent evolution
55.
Convergent Evolution
57.
Adaptive Radiation
Coevolution
58.
59.
(Darwin’s finches and beak shapes)
(insect on a leaf)
Adaptive Radiation
60.
Coevolution
61.
Convergent Evolution
Divergent evolution