Assignment

 

Assignment: Natural Selection and Guppy Evolution

According to the theory of natural selection, organisms with traits that give them a greater chance of survival are more likely to pass these traits to offspring than organisms whose traits are not especially suited for survival. When Charles Darwin sailed on his 5-year-long voyage onboard the HMS Beagle, he recorded many observations of nature. Among these records, Darwin noted variations in beak shape and size among the finch populations throughout the Galápagos Islands.

Scientists who studied these beak variations realized the differences were not random, but related to the environment in which the finches lived. They discovered that finches tended to have beak types that made it easier for the birds to eat the foods growing in their particular environment (Belk & Maier, 2013). In what type of environment might finches with large, strong beaks have a greater chance of survival than finches with small, pointed beaks? Why might the finches with the smaller, pointed beaks be more likely to survive in a different type of environment?

Like Darwin and other scientists, biologist John Endler was interested in learning how environmental changes might influence the expression of advantageous traits in particular populations. Endler applied the principles of natural selection when he developed an experiment to study changes in guppy populations. He placed guppies in different environments and predicted how the fish populations would change in order to survive in those environments. For this week’s Assignment, you perform a virtual experiment based on John Endler’s experiment. Like Endler, you hypothesize how guppy populations will change to improve their chances of survival. You complete and submit a lab report for this Assignment.

To prepare for this Assignment:

• Review Chapter 12 “An Evolving Enemy” and focus on the following:

  What the theory of natural selection asserts
  What evidence supports the theory of natural selection
  How the theory of natural selection relates to the theory of evolution

• Log on to MasteringBiology (see the Media section of the Required Resources) to review the animation “Principles of Evolution” and focus on the relationship between natural selection and evolution.

The Assignment:

By Day 5

1. Print and save to your computer the Natural Selection Lab Report document from the Natural Selection Virtual Lab. You may complete this report by hand as you complete the lab; however, by Day 7, you submit an electronic version of this document for your Assignment.
2. Complete the Natural Selection Virtual Lab. See the Required Resources section for the link to this activity.

   Fill out appropriate sections of the Natural Selection Lab Report as you complete the lab. You may complete the analysis and conclusion sections of the lab report after you exit the virtual lab.

Questions about this Assignment? Post the questions in the Contact the Instructor area, so all class members may benefit from the Instructor’s response.

Refer to the Week 5 Assignment Rubric for grading details.

By Day 7

Following the instructions below, submit your Assignment. In order to receive full credit, all Assignments are due on time. Should you encounter an unanticipated and uncontrollable life event that may prevent you from meeting an Assignment deadline, contact the Instructor immediately to request an extension. Contact information for your Instructor can be found under the Contact the Instructor area. For a full description of the late policy, please refer to the “Policies on Late Assignments” section of your Syllabus.

Submission and Grading Information

To submit your completed Assignment for review and grading, do the following:

• Please save your Assignment using the naming convention “WK5Assgn+last name+first initial.(extension)” as the name.
• Click the Week 5 Assignment Rubric to review the Grading Criteria for the Assignment.
• Click the Week 5 Assignment link. You will also be able to “View Rubric” for grading criteria from this area.
• Next, from the Attach File area, click on the Browse My Computer button. Find the document you saved as “WK5Assgn+last name+first initial.(extension)” and click Open.
• If applicable: From the Plagiarism Tools area, click the checkbox for I agree to submit my paper(s) to the Global Reference Database.
• Click on the Submit button to complete your submission.

http://mym.cdn.laureate-media.com/2dett4d/Walden/BIOL/1001/CH/mm/virtual_lab_3/index.html

Natural Selection Lab Report

Name: ________________________

Date: _________________________

Updated 05/15/2014

Purpose: To apply the principles of natural selection to the effect of predation and background on the color patterns of male guppies over a period of 15 generations.

Natural Selection Virtual Lab Schedule

Note: You will complete the online Natural Selection Virtual Lab and this lab report in the following order:

1. Link to the online Natural Selection Virtual Lab and follow the lab instructions. Stop when the STOP sign appears in the virtual lab.

2. Complete Step 1 in the Results section of this lab report.

3. Complete the Hypothesis section of this lab report.

4. Return to the virtual lab and finish conducting the virtual experiment.

5. Record your observations from the virtual experiment by completing Step 2 in the Results section.

6. Complete the Analysis and Conclusion sections of this lab report.

7. Submit the finished lab report to your Instructor, following the submission instructions in your online classroom.

Hypothesis (5 points)

Note: Complete Step 1 in the Results section first. The observations you make there are ultimately part of the results and contribute to your hypothesis. Then, write your hypothesis (see instructions below).

In the table below, explain what you expect to observe in the color patterns of the male guppies in each of the ponds based on what you know about natural selection.

Pond 1 Prediction

Pond 2 Prediction

Pond 3 Prediction

Pond 4 Prediction

Note:
After completing Step 1 in the Results section and writing your hypothesis, above, return to the Natural Selection Virtual Lab and select the NEXT button to complete the virtual experiment.

Materials and Methods

Before running this experiment you will create four different experimental ponds. The ponds will vary according to the kind of gravel (large, coarse gravel or small, fine gravel) and according to whether a guppy predator is present. In order to set up the experimental ponds you need to “drag and “drop” the correct sand size and the predators into the appropriate pond. You will then view a representative of a typical male guppy from a common pool and place a breeding population of these guppies in each of the experimental ponds. After approximately 15 guppy generations pass, the simulator will allow you to view a representative male guppy from each pond. You will observe and then record the male guppy color pattern representative of each pond in the results table and note any variations from the common ancestor.

Results (16 points)

Step 1:

a. Record your observations of the guppy color pattern before the start of the experiment in the table above.
Describe a typical male guppy at the beginning of the experiment here:

b. Complete the Gravel Type and Predator columns in the table below.

Note: After completing Step 1, complete the Hypothesis section.

Step 2: After you select the TIME button in the interactive virtual experiment, record your observations of the changes in the color patterns of the guppies in the Observations Over Time column.

Gravel Type (coarse / fine)	Predator (yes / no)	Observations Over Time. Note the color pattern of typical male guppies in each pool and how they differ from that of their common ancestor.
Pond 1
Pond 2
Pond 3
Pond 4

Analysis (25 points)

Write a 3+ paragraph analysis of your results that includes the following:

· A summary of the observations of the changes in the guppy populations in each pond.

· A statement that explains whether you observed the results you expected, as well as why you did or did not observe the expected results.

· Explicitly describe the role of natural selection and the selection pressures present in this experiment.

· A statement explaining how, if at all, you think coloration in the male guppy populations in Ponds 1 and 2 would change over time if the predators were permanently removed (Note: Explain your hypothesis in terms of selection pressures.)

· A summary of the overall knowledge you gained from this lab

Conclusion (4 points)

Write a conclusion of one or more paragraphs that includes the following:

· A brief recap of the main points in your analysis

· Propose a question about this lab topic that you would like to research in the future

Natural Selection Lab Report – 1

© 2012 Laureate Education, Inc.

©2012 Laureate Education, Inc. 1

BIOL 1001 Gen Ed Virtual Lab 3
Natural Selection
Program Transcript

[title screen]

An illustration of a university campus appears on the screen followed by the title
“Natural Selection Virtual Lab.”

The title screen disappears and slide 1 of the lab appears.

[slide 1]
An illustration of a man in a white lab coat with goggles displays on the left side
of the screen. Double doors display in the background of the slide. A large callout
appears covering most of doors and displaying text and a small illustration of a
dinosaur skeleton.

The callout indicates that the man on the slide is speaking, and the text states:
Welcome to the Natural Selection Virtual Lab. My name is Dr. Wallace. I’ll be
your assistant in this experiment.

John Endler performed an experiment with guppies (poecilia reticulata) in 1978
that is considered a classic experiment in natural selection. Much of the evidence
supporting evolutionary theory is based on comparing the anatomy and genetics
of different organisms, both in the present and across geologic time (through the
use of fossils). In fact, because evolution can take many generations to observe,
it was once thought that, outside of rapidly reproducing insects, evolution could
not be experimentally tested in the lab.

The clickable text NEXT appears in the lower right corner of the callout which you
may select to navigate to the next slide.

[slide 2]
After selecting NEXT on slide 1, the same screen displays, but the callout
changes. The dinosaur skeleton is replaced with a pair of guppies, one pink and
one blue, and the new callout text states: In 1978, John Endler changed this
perception by performing a now classic experiment demonstrating the effect of
selection pressure in guppy populations. Endler varied the environment of the
colorful guppies and made predictions based on the logic of natural selection
about how guppies might changed based on their environments.

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

©2012 Laureate Education, Inc. 2

[slide 3]
After selecting NEXT on slide 2, the same screen displays, but the callout
changes, and a paper icon labeled “Natural Selection Lab Report” replaces the
guppy illustration. When you select this lab report icon, you navigate to a PDF file
displaying the natural selection lab report, a document you need to complete the
lab assignment.

The new callout text states: In this lab, you will take Endler’s place. Here is a
summary of the activities you will complete during this virtual lab:

• Learn about guppies and their natural environment
• Learn about the purpose of Endler’s experiment
• Set up the experiment
• Form a hypothesis
• Make observations as you perform the experiment
• Complete a lab report that includes an analysis of your results

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

[slide 4: guppies]
After selecting NEXT on slide 3, a new callout entitled “Guppies” appears. The
slide displays an underwater scene in a pond. Dark brown gravel lies along the
bottom of the slide. Several green plants grow from the gravel on the left side
with green-blue water in the background above the gravel. Two similar guppies
display in the pond, but one is more colorful than the other. Both guppies have
long, slender bodies with short, fine tails. On both guppies, a light brown-yellow
color dominates the top of the fish and light gray color dominates the underbelly.
The less colorful guppy displays yellow, faded-red, and light black spots. The
more colorful guppy has larger brighter spots that are colored yellow, black, blue,
and orange-red. Small, light blue air bubbles continually move from the bottom f
the slide toward the top of the slide.

The following text also appears in the callout:
Guppies display such a colorful and varied pattern of spots that no two guppies
are exactly alike. The spots vary by size and position and are colored black, red,
yellow, and blue.

These colorful patterns are significant in guppy mating. Females are attracted to
flashy males with colorful displays that stand out in the pond environment. This
female preference is a sexual selection pressure that, over time, has resulted in
the more colorful male alleles becoming popular in guppy populations.

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

©2012 Laureate Education, Inc. 3

[slide 5: guppies]
After selecting NEXT on the guppies slide, the background and illustrations
remain the same, but a new callout appears with the text: Unfortunately, this
colorful pattern can also attract predators. Predation is, of course, also a form of
natural selection, but this pressure operates on male genes in the opposite way.

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

[slide 6: environment]
After selecting NEXT on the guppies slide, the background remains the same but
only one guppy, the less colorful one displays on the screen. The slide’s title
changes to “Environment.” Seconds after the slide appears, the dark brown
gravel changes to light-colored gravel containing a variety off-white and light-
brown shades. The guppy blends in with this new background making it more
difficult to see.

The text in the callout states:
The guppies’ environment also influences their visibility. A guppy may stand out
in one environment but be difficult to see in another.

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

[slide 7: guppy predator]
After selecting NEXT on the environment slide, the slide background and images
remain the same, but a new callout with the title “Guppy Predator” appears.
Seconds after the slide appears, a much larger fish appears on the top left side
of the slide. The large fish has two dark gray fins along its brown-gray topside.
Black spots appear along its side and its underbelly is light-yellow. The large
fish’s mouth continually opens and closes.

The text on the screen states:
The Cichlidae (Crenicichla alta) is a powerful visual hunter and a dangerous
guppy predator.”

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

[slide 8: the experiment’s purpose]

©2012 Laureate Education, Inc. 4

After selecting NEXT on the guppy predator slide, a new slide with the callout
entitled “The Experiment’s Purpose” appears. The image of Dr. Wallace displays
in the lower left side of the slide, and he is standing in a greenhouse. A callout
containing text and four small images covers most of the slide’s background.

The text on the callout states:
The purpose of this experiment is to investigate the coloration and spot patterns
in guppy populations exposed to different predatory and environmental
conditions.

The following are features you manipulate as you complete the virtual lab:

• Ponds that imitate the natural habitat for guppies
• Gravel in the ponds:

o Large, coarse gravel
o Small, fine gravel

• Guppy predator, Cichlidae
• Guppies

Here is a description of the four small images and their labels:

• The image labeled “course gravel” displays large pebbles containing a
variety off-white and light-brown shades.

• The image labeled “fine gravel” displays pebbles with colors similar to the
course gravel, but the pebbles are much smaller.

• The image labeled “guppy predator” displays the same guppy predator
described on the environment slide. It is a large fish with two dark gray fins
along its brown-gray topside. Black spots appear along its side and its
underbelly is light-yellow.

• The image labeled “guppy” displays the same less-colorful guppy on the
guppy slide. It has small long, slender body with a short, fine tail. A light
brown-yellow color dominates the top of the fish and light gray color
dominates the underbelly. The guppy displays yellow, faded-red, and light
black spots.

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

[slide 9: setting up the experiment: 1 of 5]
After selecting NEXT on the slide entitled “The Experiment’s Purpose,” a new
slide entitled “Setting Up the Experiment: 1 of 5” appears. The right side of the
slide displays text, and the left side of the slide displays various components you
will use to conduct the experiment.

Four circular blue ponds display on the left side of the slide, and the ponds are
labeled 1 through 4. Ponds 1and 2 are in the top row, and ponds 3 and 4 are in
the bottom row. Five items with rollovers appear above the pond area. Here are

©2012 Laureate Education, Inc. 5

the rollover labels and descriptions of each of these five items moving from left to
right:

• The time machine is a square box with a frame similar to a frame that
might surround a picture. A red button displays in the center of the lower
side of the frame.

• To the right of the time machine is a rectangular pool labeled “Guppies”
that contains small black fish. The fish are in motion, swimming in the
pool.

• To the right of the guppy pool is another rectangular pool. This pool is
labeled “Guppy Predators” and displays one large black fish with a tail that
moves back and forth.

• To the right of the guppy predator pool is a rectangle labeled “Coarse
Gravel.” This rectangle contains an image of large pebbles displaying a
variety off -white and light-brown shades.

• To the right of the coarse gravel is a rectangle labeled “Fine Gravel.” This
rectangle displays an image of pebbles with similar colors as the course
gravel, but the fine gravel contains much smaller pebbles.

The text on the screen states:
John Endler created ponds in a greenhouse that mimicked the guppies’ natural
environment. You will now recreate this experiment by establishing four different
kinds of ponds.

First, place your mouse cursor over each object to identify it. You will find four
containers, four ponds, and a time machine.

The clickable text BACK and NEXT appears in the lower right corner of the
callout which you may select to navigate to the previous or next slide.

[slide 10: setting up the experiment: 2 of 5]
After selecting NEXT, new text appears with instructions on how to begin the
experiment.

The text states:
Begin by placing gravel in each of the ponds. Drag the coarse gravel to ponds 1
and 3. Then click NEXT.

On this slide, the mouse’s cursor appears as an outstretched hand covered by a
blue glove. When you move the glove over the coarse gravel icon and left click
your mouse and hold, the gloved hand makes a fist. When you drag the fist over
Pond 1 and release the mouse, the fisted hand reverts to an outstretched hand
and gravel appears in Pond 1.You follow the same procedure to drag coarse
gravel into Pond 3.

©2012 Laureate Education, Inc. 6

Once you finish dragging the gravel into Ponds 1 and 3, the NEXT button
appears in the lower right corner which you select to navigate to the next step in
the experiment.

[slide 11: setting up the experiment: 3 of 5]
After selecting NEXT, new text appears with instructions on how to complete the
next step of the experiment.

The text states:
Drag the fine gravel icon to ponds 2 and 4. Then click NEXT.

The mouse’s cursor appears as an outstretched hand covered by a blue glove.
When you move the gloved hand over the fine gravel icon and left click your
mouse and hold, the gloved hand makes a fist. When you drag the fist over Pond
2 and release the mouse, the fisted hand reverts to an outstretched hand and
gravel appears in Pond 2.You follow the same procedure to drag fine gravel into
Pond 4.

Once you finish dragging the gravel into Ponds 2 and 4, the NEXT button
appears in the lower right corner which you select to navigate to the next step in
the experiment.

[slide 12: setting up the experiment: 4 of 5]
After selecting “next,” new text appears with instructions on how to complete the
next step of the experiment.

The text states:
Place guppies in each pond by dragging the guppy icon to each of the ponds.
Then click NEXT.

When you place the gloved hand over the guppies icon and left click your mouse
and hold, the gloved hand makes a fist. When you drag the fist over each pond
and release the mouse, the fisted hand reverts to an outstretched hand and tiny
black fish appear in the pond.

Once you finish dragging guppies into all four ponds, the NEXT button appears in
the lower right corner which you select to navigate to the next step in the
experiment.

[slide 13: setting up the experiment: 5 of 5]
After selecting “next,” new text appears with instructions on how to complete the
next step of the experiment.

The text states:
Place guppy predators in ponds 1 and 2 by dragging the guppy predator icon to
ponds 1 and 2. Then click NEXT.

©2012 Laureate Education, Inc. 7

When you place the gloved hand over the guppy predator icon and left click your
mouse and hold, the gloved hand makes a fist. When you drag the fist over each
pond and release the mouse, the fisted hand reverts to an outstretched hand and
one large black fish with a tail that moves back and forth appears in the pond.

Once you finished dragging a guppy predator into ponds 1 and 2, the NEXT
button appears in the lower right corner which you select to navigate to the next
step in the experiment.

[slide 14: writing your hypothesis]
After selecting NEXT, a new callout appears with the title “Writing Your
Hypothesis” and with text listing instructions on how to complete the next step of
the experiment.

The text states:
Stop! Before you continue, use the magnifying glass to observe the guppy in
each of the four ponds. Then complete the following in the Natural Selection Lab
Report:

1. Results section, step 1
2. Hypothesis section

Then, return here to the lab and select the NEXT button to continue with the
experiment.

On this screen, the mouse cursor appears as a magnifying glass. When you
move the magnifying glass over each pond and click, a close-up of the guppy
with its gravel background appears. Each pond displays one guppy and the
guppies look identical. They look like the less colorful guppy displayed on the
guppies slide earlier in the lab. Each guppy has a small, long, slender body with
a short, fine tail. A light brown-yellow color dominates the topside of the fish and
a light gray color dominates the underbelly. The guppy displays yellow, faded-
red, and light black spots.

The course gravel in the background of ponds 1 and 3 is identical, and the fine
gravel in ponds 2 and 4 is identical. The course gravel in ponds 1 and 3 contains
large pebbles in a variety off-white and light-brown shades of color. The fine
gravel in ponds 2 and 4 is similar in color to the coarse gravel, but the pebbles
are smaller.

[slide 14: completing the experiment]
After examining each of the pond’s guppies and completing step 1 in the results
section and the entire hypothesis section of the Natural Selection Lab Report,
you select NEXT.

©2012 Laureate Education, Inc. 8

A new callout with the title “Completing the Experiment” appears. A large red
zero now appears in the Time Machine, and the red button at the bottom center
of the Time Machine frame begins to blink.

The following new text appears on the slide:
You are now ready to carry out the experiment. Click the Time Machine to allow
fifteen guppy generations to pass. Then click NEXT.

After clicking the time machine, the red number counts upward from 0 to 1, 2, 3,
etc., until it stops at number 15.

[slide 15: the experiment]

After selecting NEXT, the callout entitled “The Experiment” appears on the slide
with the following text:
Using the magnifying glass icon, click each pond to observe the guppies. Record
your observations of the guppy color patterns in each pond in the title in the
Results section of the Natural Selection Lab Report. Then, complete the Analysis
and Conclusion sections and submit the report to your Instructor. Be sure to
follow any additional instructions in your assignment for this week.

On this slide, the mouse cursor appears as a magnifying glass. When you move
the magnifying glass over each pond and click, a close-up of the guppy after 15
generations appears next to a close-up of the guppy as it appeared at the start of
the experiment.

Here are the descriptions of how the guppies in each pond appear at the end of
15 generations:

• Pond 1 guppy (coarse gravel with a guppy predator): After 15 generations,
the guppy is elongated and its spots have become larger but faded in
color, making the guppy blend in more with the coarse gravel background.

• Pond 2 guppy (fine gravel with a guppy predator): After 15 generations,
the guppy is elongated and its spots have become smaller but faded in
color, making the guppy blend in more with the fine gravel background.

• Pond 3 guppy (coarse gravel with no guppy predator): After 15
generations, the guppy has become more colorful. Its light orange-red and
yellow spots are now bright orange-red and yellow; and the guppy now
also displays a large blue and white spot making it stand out against the
coarse gravel background.

• Pond 4 guppy (fine gravel with no guppy predator): After 15 generations,
the guppy has become more colorful. Its light orange-red and yellow spots
are now bright orange-red and yellow; and the guppy now also displays a

©2012 Laureate Education, Inc. 9

large blue and white spot making it stand out against the fine gravel
background.