The second equation says that 100% of individuals in the population will have one of these genotypes: AA, Aa, and aa. The first equation says that if there are only two alleles for a gene, one dominant and one recessive, then 100% of the allelesĪre either dominant (p) or recessive (q). Two equations are used to calculate the frequency of alleles in a population, where p represents the frequency of the dominantĪllele and q represents the frequency of the recessive allele: If allele frequencies or genotype frequencies change over time, then evolution is occurring.
If the population is inĮquilibrium, the overall number of A alleles and a alleles in the gene pool will remain constant, as will the proportion of the Each individual has one of three genotypes: AA, Aa, or aa. Suppose, forĮxample, a gene has two alleles, A and a. To determine whether a population’s gene pool is changing, we need to be able to calculate allelic frequencies. The population is very large and well mixed. The genetic definition of “evolution” is “a change to a population’s gene pool.” “Gene pool” is defined as “the total number ofĪlleles present in a population at any given point in time.” According to the Hardy-Weinberg theorem, a population is inĮquilibrium (and is therefore not evolving) when all of the following conditions are true: PART 2: REVIEWING THE PRINCIPLES OF THE HARDY-WEINBERG THEOREM Use the data and what you have learned about evolution to explain how mutation is a random process, but natural selection You can assume that environmental conditions do not change over the 100 years.Ĥ. 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 theģ. Explain the presence of dark-colored mice at location A. Remember that “fitness” is defined by an organism’sĪbility to survive and produce offspring.Ģ. Explain why a rock pocket mouse’s color influences its overall fitness. You may recordĪll 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 Once you are satisfied that you are correct, fill out the data table below using the counts you recorded above theĥ. 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? How does this trait affect the survival of the mice in different environments? Why are some mice light colored and some mice dark colored?ĭoes fur color provide any selective advantage or disadvantage? What specific trait did researchers study in this investigation? Answer the following as you watch the film: You arranged the illustrations is correct.
Watch, look for an explanation for the differences among the illustrations that will help you confirm that the order in which Watch the Howard Hughes Medical Institute’s short film The Making of the Fittest: Natural Selection and Adaptation. Positioned the others in the sequence as you did.ģ. Explain how you decided which illustration represents the most recent rock pocket mouse population and why you Indicate your order in the spaceīelow: _Ģ. Place the illustrations in what you think is the correct order from oldest to most recent. Shows the color variation at two different locations, A and B, at a particular moment in time. The illustrations (The teacher passed out) represents snapshots of rock pocket mouse populations. Volcanic rocks that formed from cooling lava flows are found, separated by several kilometers of light- colored substrate. Most of the landscape consists of light-colored sand and rock, but patches of dark Materials, that make up the desert floor. There are also two major colors of substrate, or surface There are twoĬommon 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 Grams, this tiny mouse weighs about as much as a handful of paper clips. Name _ĬOLOR VARIATION OVER TIME IN ROCK POCKET MOUSE POPULATIONSĪ typical rock pocket mouse is about 170 millimeters long from nose to rump, shorter than an average pencil.
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