1. Overview: 1.Describe your group’s scenario, making sure to describe both the habitat and the diversity of color amongst your initial prey population. 2.Complete the following hypothesis statement: “If camouflage is an effective adaptation against predation, then, through generations…” 3.Predators stand with their backs towards the habitat while the architect spreads out the initial population on the habitat. 4.Organizer signals for predators to turn around and start the process of predation by capturing one bead before turning their backs to the habitat. This process continues until 75% (30 of 40) beads of the initial population have been removed. 5.The organizer will then remove the remaining beads and count the number of survivors of each color. This data is then recorded on the data analysis page. 6.To simulate reproduction, we must assume that like colors mate. The organizer will multiply each color by four and collect the appropriate number of new beads, which repopulates the habitat with the next generation. 7.This exercise is then repeated up to four times. Mechanisms of Evolution By René A. Shroat-Lewis Objectives: We will use experiments to examine the process of natural selection, which is driven by variation in genetic traits within a population, the potential for offspring to inherit traits from their parents, and differential reproduction within a population (i.e. “survival of the fittest”). Using this exercise we will see how adaptation increases the potential for survival. Computer simulations that examine evolution are often extremely complex, and require significant computing power. Instead, in this set of exercises, we can explore evolution through several experimental exercises and a bunch of bead counting. Materials: Colored beads (prey) Multi-colored fabric (habitat) Ziploc baggies Data analysis page Figure 2: Example of habitat board. Any type of fabric can be used, but it is easy for students to see how prey can effectively camouflage themselves in a busy habitat. Evaluation and Comprehension: This is a good exercise that illustrates how natural selection works, and how important adaptation is to survival in a changing world. It allows students to see how different scenarios can change the make-up of a standing population (i.e. the shape of the distribution). Note: This activity was adapted from an activity by Linda Kah at the University of Tennessee Knoxville Differing Dynamics of Natural Selection This initial exercise can be modified in various ways: 1.Directional selection: Active predators have learned that “light” colored prey tend to be sour and foul tasting. 2.Stabilizing selection: Active predators seek prey with more color contrast. “Light” and “dark” prey are removed preferentially. 3.Disruptive selection: Predators are a lazy bunch – prey is prey and it all tastes the same. Therefore, predators eat the most common beads and hate searching for the rare forms. Figure 1: Example of data analysis page for generation 0 and 1. Figure 3: Example of initial population and extra beads for mating.