color variation over time in rock pocket mouse populations

A classic illustration of 'survival of the fittest.' As the cities reduced the pollution, the tree trunks lightened up, and so did the moths. Eventually, black became the norm for urban peppered moths.

Better camouflaged than their light-colored brethren, the dark forms survived and proliferated. In a short time, though, dark variants of the moths sprang up. Coal soot from burgeoning industry gradually blackened tree trunks in urban areas, and left the moths more vulnerable to predators. In pre-industrial England, most peppered moths had mottled grey wings, camouflaging well with the birch trees upon which they rested. The story is reminiscent of the peppered moth lesson from high school biology class. Almost all of the mice collected from the volcanic formations had dark coats-the better to stay concealed from hungry owls, which can pick off mice from contrasting backgrounds even at night. Nachman's group collected pocket mice from two of these black rock islands-the Pinacate formation in southwestern Arizona and the Pedro Armendaris formation of New Mexico. But scattered throughout the southwest are islands of black basaltic rock formed from not-so-ancient lava flows. Most of the mice have light tawny fur, which blends in well with the desert granite substrates they typically inhabit. Nachman, examined the coat colors of rock pocket mice. Use the data and what you have learned about evolution to explain how mutation is a random process, but natural selection is not random.The group, led by Professor of ecology and evolutionary biology Michael W. You can assume that environmental conditions do not change over the 100 years.Ĥ. Base your prediction on trends in the data you have organized. a prediction that describes what the population will look like 100 years in the future.an explanation of what caused the changes, and.a description of how the population has changed over time,.

Write a scientific summary that describes changes in the rock pocket mouse populations at location B. Why didn’t this phenotype become more common in the population?ģ. Explain the presence of dark-colored mice at location A. Remember that “fitness” is defined by an organism’s ability to survive and produce offspring.Ģ. Explain why a rock pocket mouse’s color influences its overall fitness. You may record all of your data for each time period (A and B) on one bar graph or split A and B and make two graphs.ġ. Be sure to provide an appropriate title for the graph, and titles and labels for the x- and y-axes. Use colored pencils to prepare a bar graph based on the data that shows the distribution of the mice at locations A and B through time. Once you are satisfied that you are correct, fill out the new data table, recording the counts in order of occurrence.Ħ. Using what you learned by watching the film, check the order in which you arranged the illustrations. What can explain the differences among the illustrations?ĥ.What role does the rock pocket mouse play in the desert food web?.Does fur color provide any selective advantage or disadvantage?.Why are some mice light colored and some mice dark colored?.Watch the video: Think about the following as you watch the film: Explain how you decided which illustration represents the most recent rock pocket mouse population and why you positioned the others in the sequence as you did. Rank the illustrations what you think is the correct order from oldest to most recent.ģ. Record your counts in a chart that resembles the one to the right.Ģ. Count the number of light-colored and dark-colored mice present at each location at each moment in time. Each quadrant illustration shows the color variation at two different locations, A and B, at a particular moment in time. The illustrations on the back represent snapshots of rock pocket mouse populations. Most of the landscape consists of light-colored sand and rock, but patches of dark volcanic rocks that formed from cooling lava flows are found, separated by several kilometers of light-colored substrate. There are also two major colors of substrate, or surface materials, that make up the desert floor. There are two common varieties-a light-colored variety and a dark-colored variety. You can find populations of rock pocket mice all over the Sonoran Desert in the southwestern United States. Rock pocket mice, however, have had an enormous impact on science. And at just 15 grams, this tiny mouse weighs about as much as a handful of paper clips. Color variation over time in rock pocket mouse populations.Ī typical rock pocket mouse is about 170 millimeters long from nose to rump, shorter than an average pencil.