Study on Wild Guppies: Online Simulation of Endler's Work

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In the 1970s, an investigator named John Endler traveled to Trinidad in the 1970s to study wild guppies. The guppies live in small streams that flow down the mountains from pool to pool. The experiment will take part on an online simulation of Endler's work. The group of members is responsible for collecting data, formulating a hypothesis, and running a series of experiments. They will find out about the interplay between natural selection and sexual selection in this wild population of guppies. They will ultimately find out the effects on the guppy population and their color distribution depending on the predator that lives in their environment. Endler wondered how the trade-off between attracting mates and affecting predators affects the coloration in male guppies. In pools that had few predator species, male guppies tended to be brightly colored, whereas predators are causing guppy populations to become drabber. This occurs because the predators are preying on the most brightly colored individuals and eliminating them from the gene pool. Therefore, guppy populations are evolving to more closely match, or stand out from their environment. Endler hypothesized that intense predation caused natural selection in male guppies, favoring the trait of drab coloration. He further tested his hypothesis by transferring brightly colors guppies to a pool with many predators. As he predicted, over time the transplanted guppy population became less brightly colored. Females tend to look for the bright colored male guppies in the pool and mate with them. This enables those males to have a higher probability of passing their genes on to their next generation. In the simulation, predators can dramatically influence the evolution of a population of guppies, but change does not occur quickly during the testing of one generation for each trial. (Before columns on graphs in the Data section of the simulation report) Scientists believe that they see changes in just a few generations, but more often there are significant trends when the simulation is ran after 7 generations or more. So, the ten generations for each different trial was calculated under the after columns of the graphs also in the Data section of the simulation. There were three predators involved in the experiment. There were Rivulus, Acara, and Cichlid predators. Also, there were different types of colored guppies in the gene pool. They are the brightest, bright, drab, and the drabbest colored guppies. There were certain trials that were tested to reveal the certain descriptions about the predators affecting the guppy population. Since the average male guppy in pool 1 is brightly colored and 30 Rivulus are living there, Rivulus do not prefer to eat brightly-colored guppies. Also, since pool 2 and pool 3 show differences in guppy appearances, Blue acara eat bright and drab colored guppies. Then, since pool 3 has few Rivulus and many Blue acara and Cichlids, and the average male guppy is like drab with drabbed spots, Blue acara and cichlids do not prefer drab colored guppies. Problem/Objectives

The purpose of this activity is to analyze how guppy populations change over time. The simulation activity allows individuals to start with a pool of guppies and a choice of predators, in this case there are three. Certain predator or predators may be in the guppy population at the same time. Individuals will be able to watch what happens to the guppy population and how the introduction of predators can affect the guppy's appearance. The simulation will help a person understand what pressures drive guppy evolution. The field of population genetics examines the amount of genetic variation within populations and the processes that influence this variation. A population is defined as a group of interbreeding individuals that exist together at the same time. The guppy simulation represents this definition of a population because there are male guppies that mate with the females...
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