Assignment

WK5transcript.pdf

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.

[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.

[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]

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

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.

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.

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.

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

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