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

 

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